February 2014 | Legend Techz

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Thursday, 27 February 2014

10. What is rectangular waveguide

February 27, 2014 legend

Rectangular waveguide is one of the types of waveguides.The shape of it is a hollow metallic tube with rectangular cross section as shown in the figure with dimension 'a' along x axis and dimension 'b' along y axis.

♦ Electric and magnetic fields of the signal is confined within the waveguide and no power is lost.

♦ Since normally waveguide are air filled a dielectric loss exists but negligible.Also some power lost as heat at walls of the waveguide but small.

♦ Possible to send several electromagnetic waves simultaneously through waveguide

♦ A rectangular waveguide supports TE and TM modes but not TEM waves

♦ A given waveguide have a cut off frequency for each mode, below which attenuation takes place.

♦ The dominant mode in rectangular waveguide is TE₁₀

♦ The mode supported by the waveguide is determined by the dimensions of the waveguide and the dielectric inside the waveguide.

35. Explain about Ideal Low Pass Filter (ILPF) in frequency domain.

February 27, 2014 legend

Lowpass Filter:

The edges and other sharp transitions (such as noise) in the gray levels of an image contribute significantly to the high-frequency content of its Fourier transform. Hence blurring (smoothing) is achieved in the frequency domain by attenuating us the transform of a given image.

G (u, v) = H (u, v) F(u, v)

where F (u, v) is the Fourier transform of an image to be smoothed. The problem is to select a filter transfer function H (u, v) that yields G (u, v) by attenuating the high-frequency components of F (u, v). The inverse transform then will yield the desired smoothed image g (x, y).

Ideal Filter:

A 2-D ideal lowpass filter (ILPF) is one whose transfer function satisfies the relation

\[H(u,v)=\begin{cases}1 & D(u,v) \leq D_{0}\\0 & D(u,v) > D_{0}\end{cases}\]

where D is a specified non negative quantity, and D(u, v) is the distance from point (u, v) to the
origin of the frequency plane; that is,
\[D(u,v)=\sqrt{(u^{2}+v^{2})}\]
Figure 3 (a) shows a 3-D perspective plot of H (u, v) u a function of u and v. The name ideal filter indicates that oil frequencies inside a circle of radius D₀ are passed with no attenuation, whereas all frequencies outside this circle are completely attenuated.

Fig.3 (a) Perspective plot of an ideal lowpass filter transfer function; (b) filter cross
section.

The lowpass filters are radially symmetric about the origin. For this type of filter, specifying a cross section extending as a function of distance from the origin along a radial line is sufficient, as Fig. 3 (b) shows. The complete filter transfer function can then be generated by rotating the cross section 360 about the origin. Specification of radially symmetric filters centered on the N x N frequency square is based on the assumption that the origin of the Fourier transform has been centered on the square.

For an ideal lowpass filter cross section, the point of transition between H(u, v) = 1 and H(u, v) = 0 is often called the cutoff frequency. In the case of Fig.3 (b), for example, the cutoff frequency is Do. As the cross section is rotated about the origin, the point Do traces a circle giving a locus of cutoff frequencies, all of which are a distance Do from the origin. The cutoff frequency concept is quite useful in specifying filter characteristics. It also serves as a common base for comparing the behavior of different types of filters.

The sharp cutoff frequencies of an ideal lowpass filter cannot be realized with electronic components, although they can certainly be simulated in a computer.

Tuesday, 25 February 2014

9. What is degenerate mode in waveguide.

February 25, 2014 legend

In a waveguide when two or more modes have the same cut off frequency then they are said to be degenerate modes.

In a rectangular waveguide the TE_mn and TM_mn with m ≠ 0 and n ≠ 0 are degenerate modes.

For a square waveguide for which a = b, all the TE_pq, TE_qp, TM_pq, TM_qp modes are degenerate.

Sunday, 23 February 2014

8. what is dominant mode in waveguides

February 23, 2014 legend

For a waveguide the dominant mode is the mode with the lowest cut off frequency.

Single mode propagation reduce losses, so we use dominant mode propagation.The waveguide can be operated only in the dominant mode for a certain range of frequency, this range of frequency extend from cut off frequency of dominant mode to the cut off frequency of next higher mode.

In rectangular waveguide the dominant mode is TE₁₀, and for circular waveguide the dominant mode is TE₁₁.

7. what are modes in waveguides

February 23, 2014 legend

Lets explain what are modes in waveguide mean.For every type of waveguide the electromagnetic waves inside the waveguide can have an infinite number of distinct electromagnetic field patterns or configurations, these distribution of electric and magnetic fields in a waveguide is called modes.

The characteristics of these modes depend upon the cross-sectional dimensions of the conducting waveguide, the type of dielectric material inside the waveguide, and the frequency of operation. Waveguide modes are typically classed according to the nature of the electric and magnetic field components E_z and H_z.These components are called the longitudinal components of the fields.So the types of modes in a waveguide are

✎ TE modes. Transverse-electric modes, sometimes called H modes. These modes have E_z = 0 and H_z ≠ 0 at all points within the waveguide, which means that the electric field vector is always perpendicular (i.e., transverse) to the waveguide axis. These modes are always possible in waveguides with uniform dielectrics.
✎ TM modes. Transverse-magnetic modes, sometimes called E modes. These modes have H_z = 0 and E_z ≠ 0 at all points within the waveguide, which means that the magnetic field vector is perpendicular (i.e., transverse) to the waveguide axis. Like TE modes, they are always possible in waveguides with uniform dielectrics.
✎ EH modes. EH modes are hybrid modes in which neither E_z nor H_z are zero, but the characteristics of the transverse fields are controlled more by E_z than H_z . These modes are often possible in waveguides with inhomogeneous dielectrics.
✎ HE modes. HE modes are hybrid modes in which neither E_z nor H_z are zero, but the characteristics of the transverse fields are controlled more by H_z than E_z . Like EH modes, these modes are often possible in waveguide with inhomogeneous dielectrics.
✎ TEM modes.Transverse-electromagnetic modes, often called transmission line modes. These modes can exist only when a second conductor exists within the waveguide, such as a center conductor on a coaxial cable. Because these modes cannot exist in single, closed conductor structures, they are not waveguide modes.

A waveguide will have a definite cut off frequency for each mode.Also it is possible to propagate several modes within a waveguide.

The different modes are named with subscript m and n, for example TE_mn where m is the number of half wave variations across x axis and n is the number of half wave variations across y axis.

Friday, 21 February 2014

6. What is a waveguide. Explain?

February 21, 2014 legend

A wave-guide is a hollow conducting pipe, of uniform cross-section, used to transport high frequency electromagnetic waves (generally, in the microwave band) from one point to another. The main advantage of wave-guides is their relatively low level of radiation losses (since the electric and magnetic fields are completely enclosed by a conducting wall) compared to transmission lines.

Also waveguide can be any medium that support the transmission or propagation of electromagnetic wave, so microwave waveguides can be a co-axial conductor, parallel plates and the above said hollow single conductor.And the term waveguides are generally used for these hollow conducting pipes.

Usually hollow waveguides are manufactured using brass, bronze, aluminium. Some times the inner surface is coated with silver or gold to avoid ohmic losses at high frequencies.

The hollow waveguides can take any shape of cross section but commonly seen are

✎ Rectangular

✎ Circular

✎ Elliptical

Depending upon the shape and dimensions of the waveguide there is a cut off frequency of transmission. Only the waves having frequency greater than cut off frequency (f_c) will be propagated. Hence waveguides act as a high pass filter with cut off frequency f_c.

Also a TEM wave cannot be propagated through a hollow waveguide.

Monday, 17 February 2014

11. What are the Product Design Specifications (PDS) to develop a new electronic product?

February 17, 2014 legend

PRODUCT DESIGN SPECIFICATION

In order to provide specific guidance about how to design and engineer a product, development teams establish a set of specifications, which spell out in precise, measurable detail what the product has to do to be commercially successful. The specifications must reflect the customer needs, differentiate the product from the competitive products, and be technically and economically realizable. A specification consist of a matric, defining a quality and a value associated for it. Eg. Max. Voltage (matric) = 230V (value)

Specifications are typically established at least twice. Immediately after identifying the customer needs, the team sets target specifications. After concept selection and testing, the team develops final specifications.

TARGET SPECIFICATIONS

Target specifications represent the hopes and aspirations of the team, but they are established before the team knows the constraints the product technology will place on what can be achieved. The team’s efforts may fail to meet some of these specifications and may exceed others, depending on the details of the product concept the team eventually selects.

The process of establishing the target specifications entail four steps:

1.Prepare the list of metrics.
2.Collect competitive benchmarking information.
3.Set ideal and marginally acceptable target values.
4.Reflect on the results and the process.

1.PREPARE THE LIST OF METRICS

The most useful metrics are those that reflect as directly as possible the degree to which the product satisfies the customer needs. The relationship between needs and metrics is central to the entire concept of specifications. The working assumption is that a translation from customer needs to a set of precise, measurable specifications is possible and that meeting specifications will therefore lead to satisfaction of the associated customer needs.

A few guidelines:

• Metrics should be complete.
• Matrics should be dependent, not independent, variables.
• Metrics should be practical.
• Some needs cannot easily be translated into quantifiable metrics.
• The metrics should include the popular criteria for comparison in the marketplace.

2.COLLECT COMPETITIVE BENCHMARKING INFORMATION.

Unless the team experts to enjoy a total monopoly, the relationship of the new product to competitive products is paramount in determining commercial success. While the team will have entered the product development process with some idea of how it wishes to compete in the market place, the target specifications are the language the team uses to discuss and agree on detailed positioning of its product relative to existing products, both its own and competitors.

The benchmarking chart is conceptually very simple. For each competitive product, the values of the metrics are simply entered down a column. Gathering these data can be very time consuming, involving (at the least) purchasing, testing, disassembling , and estimating the production costs of the most important competitive products.

The benchmarking exercise helps in identifying differences with competitive products and taking positioning decisions are mentioned. It also helps in appreciating the differences which may not be appearing so important. Ex: TATA ACE, the subjective differences were more benchmarking helped in defining the clear distinction for Ace from the available indirect competitive product options.

3.SET IDEAL AND MARGINALLY ACCEPTABLE TARGET VALUES

In this step, the team synthesizes the available information in order to actually set the target values for the metrics. Two types of target values are useful: an ideal value and marginally acceptable value. The ideal value is the best result the team could hope for. The marginally acceptable value is the value of the metric that would just barely make the product commercially viable. Both of these targets are useful in guiding the subsequent stages of concept selection, and for refining the specifications after the product concept has been selected.

4.REFLECT ON THE RESULTS AND THE PROCESS

The team may require some iteration to agree on the targets. Reflection after each iteration helps to ensure that the results are consistent with the goals of the project.
Once the targets have been set, the team can proceed to generate solution concepts.

The target specifications then can be used to help the team select a concept and will help the team know when a concept is commercially viable.

FINAL SPECIFICATIONS

Final specifications are developed by assessing the actual technological constraints and the expected production costs using analytical and physical models. During this refinement phase the team must make difficult trade-offs among various desirable characteristics of product.

The five step process for refining the specifications is:

1. Develop technical models of the product.
2. Develop a cost model of the product.
3. Refine the specifications, making trade-offs where necessary.
4. Flow down the specifications as appropriate.
5. Reflect on the results and the process.

1.DEVELOP TECHNICAL MODELS OF THE PRODUCT

A technical model of the product is a tool for predicting the values of the metrics for a particular set of design decisions. The team will be able to accurately model the product analytically, perhaps by implementing the model equations in a spreadsheet. Such a model allows the team to predict rapidly what type of performance can be expected from a particular choice of design variables, without costly physical experimentation.

2.DEVELOP A COST MODEL OF THE PRODUCT

The goal of this step of the process is to make sure that the product can be produced at the target cost. The target cost is the manufacturing cost at which the company and its distribution partners can make adequate profits while still offering the product to the end customer at a competitive price.
For most of the products, the first estimates of manufacturing costs are completed by drafting a bill of materials and estimating a purchase price or fabrication cost for each part. At this point in the development process the team does not generally know all of the components that will be in the product, but the team nevertheless makes an attempt to list the components it expects will be required.

3.REFINE THE SPECIFICATIONS, MAKING TRADE-OFFS WHERE NECESSARY

Once the team has constructed technical performance models where possible and constructed a preliminary cost model, these tools can be used to develop final specifications. Finalizing specifications can be accomplished in a group session in which feasible combinations of values are determined through the use of the technical models and then the cost implications are explored.
One important tool for supporting this decision-making process is the competitive map.

4.FLOW DOWN THE SPECIFICATIONS AS APPROPRIATE

Establishing specifications takes on additional importance and is substantially more challenging when developing a highly complex product consisting of multiple subsystems designed by multiple development teams. In such a context, specifications are used to define the development objectives of each of the subsystems as well as for the product as a whole. The challenge in this case is to flow down the overall specifications to specifications for each subsystems.

5.REFLECT ON THE RESULTS AND THE PROCESS

As always, the final step in the method is to reflect on the outcome and the process.

The specifications process is facilitated by several simple information systems which can easily be created using conventional spreadsheet software. Tools such as the list of metrics, the needs-metrics matrix, the competitive benchmarking charts, and the competitive maps all support the team’s decision making by providing the team with a way to represent and discuss the specifications.

10. Explain why Timing Analysis is important in the product design process. Explain any one Timing Analysis Tool

February 17, 2014 legend

Timing Analysis in Product Design Process

Product Design/Development Process is the sequence of steps or activities which an enterprise employs to conceive, design, and commercialize a product.Many of these steps and activities are intellectual and organizational rather than physical. The six phases of the generic development process are:

1.Planning

2.Concept development

3.System level design

4.Detail design

5.Testing and refinement

6.Production ramp-up

A well-defined development process helps to ensure product quality, facilitate coordination among team members, plan the development project, and continuously improve the process.

The first phase, Product Planning, is a periodic process that considers the portfolio of product development projects to be executed. A well defined planning ensures the success of targeted product in the market. It is likely that the firm cannot afford to invest in every product development opportunity in its desired balanced portfolio of projects. As timing and resource allocation are determined for the most promissing projects, too many projects will invariably compete for too few resources. As a result, the attempt to assign resources and plan timing almost always results in a return to the prior evaluation and prioritization step to prune the set of projects to be pursued.

Determining the timing and sequence of projects, sometimes called pipeline management, must consider a number of factors, including :

→ Timing of product introductions : Generally the sooner a product is brought to market the better. However, launching a product before it is of adequate quality can damage the reputation of the firm

→ Technology readiness : The robustness of the underlying technologies plays a critical role in the planning process. A proven, robust technology can be integrated into products much more quickly and reliably

→ Market readiness : The sequence of product introductions determines whether early adopters buy the low-end product and may trade up or whether they buy the high-end product offered at a high initial price. Releasing improvements too quickly can frustrate customers who want to keep up; on the other hand releasing new products too slowly risks lagging behind competitors.

→ Competition : The anticipated release of competing products may accelerate the timing of development projects.

The Product Plan

The set of projects/tasks(to achieve larger gains from specialization) approved by the planning process, sequenced in time, becomes the product plan. The plan may include a mix of fundamentally new products, platform projects, and derivative projects of varying size. Product plans are updated on a periodic basis, perhaps quarterly or annually, as a part of the firm’s strategic planning activity.

Relative timing of design process for two types of products

To explain the timing of design effort, it is convenient to classify products as:

◈ Technology-driven products : The primary characteristic of a technology driven product is that its core benefit is based on its technology,or its ability to accomplish a specific technical task.
Eg : A hard disc drive for a computer is largely technology driven

◈ User-driven products : The core benefit of a user driven product is derived from the functionality of its interface and/or its aesthetic appeal. Typically there is a high degree of user interaction for these products.
Eg : An office chair is largely user driven

The fig. below shows that design is incorporated into the product development process during the later phases(Concept testing onwards) for a technology driven product and throughout the entire product development process(Identification of customer needs onwards) for a user driven product.

Timing Analysis Tools

Time management seems at first to be a modern concept, but really it isn't. The first step in time management is keeping track of it, and so every time-keeping device going back to the dawn of recorded history is a time management system.

Time management tools can be broken down into four generations:

First generation ones are clock and alarms. Yes, your alarm clock, that vile thing you slap into silence every morning, is one. Extensions of this concept are digital devices which can sound alarms when a task is done.

Second generation tools are calendars and appointment books. These can be both paper and digital. The digital version is infinitely more useful, because you can set reminders for deadlines and errands. Calendar tool software runs the gamut from PDAs to laptop and desktop accessories. A calendar tool should come by default with just about any operating system sold - there's even plug-in apps for phones now.

Third-generation tools are planners, organizers, and controllers. These are done more on an industrial scale - for instance, software an office would use for dispatching mobile units and keeping shifts covered. However, a simple thing like a software to-do list or a desktop notes application uses the same concept on a personal scale.

Fourth-generation tools are the personal skills you use to combine the above three categories and use them wisely and effectively. In some cases, this can also involve timers and control systems. Some tech professionals use a time-tracking system to be able to bill clients by the hour. Anything you use personally, even tying a ribbon around your finger to remind you of an appointment, counts here too.

Time Management Matrix

One of the most commonly used timing analysis tool is the Time Management Matrix proposed by Stephen Covey in his book “First Things First”. A Time Management Matrix can help you discover how much time you might be wasting. The Matrix has four quadrants.

Quadrant 1: Important and Urgent

Only crisis activities should be in here. If you have included exams and papers here, you are probably not allowing yourself enough time to fully prepare. If you continue at this pace you could burn yourself out!

Quadrant 2: Important and Not Urgent

This is where you define your priorities. What’s important in your life? What will keep you balanced? For example, you may know that good nutrition, sleep, recreation, and maintaining healthy social relationships are important but do you consciously make time for them in your daily or weekly routine? Managing your life and the lifestyle will help you manage your time.

Quadrant 3: Not Important and Urgent

While you may feel that activities, such as instant messaging, need your attention right away, too much time spent on Quadrant 3 activities can seriously reduce valuable study time. This may leave you feeling pulled in too many directions at once.

Quadrant 4: Not Important and Not Urgent

If you’re spending many hours on Quadrant 4 activities, you’re either having a great deal of fun or spending a lot of time procrastinating! Remember, the objective is balance.

Thursday, 13 February 2014

5. Compare waveguides and two wire transmission lines

February 13, 2014 legend

Here we are comparing waveguides and two wire transmission lines.

☞ For frequencies higher than 3 GHZ, the transmission of electromagnetic waves along transmission lines and cables is not possible because of high loss, here a metallic tube can be used to transmit electromagnetic waves.

☞ A hollow metallic tube of uniform cross section which transmits electromagnetic waves by successive reflections from the inner walls of the tube is called waveguide.

Similarities between two wire transmission line and waveguide :-

1. As the wave propagates, they gets attenuated in both.

2. Irregularities or mismatches in the transmission line and waveguide causes reflection and thus standing waves.

3. Reflected wave can be eliminated by proper impedance match in both.

Disimilarities :-

1. Depending upon the shape and dimension of the waveguide, there is a cut off frequency f_c, frequencies f > f_c can only pass through it. Thus it acts as a high pass filter with cut off frequency f_c.

2. Waveguide is a one conductor system, the whole body of the waveguide acts as the ground and the wave propagates through multiple reflections from the walls of the waveguide.

3. Transmission through waveguide is governed by field theory while in transmission line by circuit theory.

4. Velocity of propagation of wave inside a wave guide is different from that through free space due to reflections.

Tuesday, 11 February 2014

CUSAT study material and notes ECE

February 11, 2014 legend

Hi everyone i am providing study material and notes for CUSAT syllabus B.Tech ECE. Also useful for all other universities.

For Digital Image Processing Click Here

For Microwave Engineering Click Here

For Electronic Product Design Click Here

Microwave Engineering notes study material index

February 11, 2014 legend

Hi everyone i am sharing my lecture notes on Microwave Engineering, these study material is as per CUSAT Syllabus but will be useful to all other universities. Check back frequently more Questions and materials will be added.

◈ 2-mark Questions and answers part 1

◈ 2-mark Questions and answers part 2

1. Why Microwave is called Microwave?

2. List various Microwave frequency bands as table

3. Explain the advantages and disadvantages of Microwaves.

4. what are the applications of microwaves.

5. Compare waveguides and two wire transmission lines

6. What is a waveguide. Explain?

7. what are modes in waveguides.

8. what is dominant mode in waveguides.

9. What is degenerate mode in waveguide.

10. What is rectangular waveguide

11. what is waveguide cutoff frequency , guide wavelength , phase velocity , group velocity , propagation constant

Manley Rowe Power or Energy Relations Derivation

index / Microwave

Monday, 10 February 2014

9. Identify how an electronic product should be launched & explain how customer needs are identified for new product.

February 10, 2014 legend

Once a product is developed, effectively product launch becomes the critical step to its success. The Product Launch Process must address all the steps necessary to

• Start volume production
• Plan and execute marketing activities,
• Develop needed documentation
• Train sales and support personnel (internal and external)
• Fill channels, and
• Prepare to install and support the product.

An improved product launch process results in faster time-to-market and time-to-profit. Activities are better planned and coordinated and more tightly integrated.

The following serves as a checklist for product launch activities:

☞ Planning:
o A product launch plan has been prepared covering all activities to be performed by Engineering, Manufacturing, Marketing, Sales, Product Support, and Field Service.
o Functional departments understand their responsibilities for launch activities.

☞ Technical
o Product performance has been evaluated through testing and qualification and the product meets its defined requirements.
o All product design documentation has been completed and approved.
o Technical data sheets have been prepared.

☞ Operations/Procurement

o Required manufacturing process documentation or outputs (e.g., work instructions, CNC programs, manning plans, etc. are complete.
o Production processes have been proven using either pilot production lines or actual production lines.

☞ Marketing and Sales

o Market receptivity has been evaluated by key customer feedback, focus groups, test markets, or beta tests prior to launch.
o A promotion and advertising plan has been developed.

☞ Product Support

o Necessary support resources are hired and in place.
o Service and support personnel have been trained or a phased training program is underway.

A key success factor in developing a new product is to understand and act on the unique needs of high value customers.

Customers have six basic buying needs pertaining to the product:
1.Safety.
2.Performance.
3.Appearance.
4.Comfort.
5.Economy.
6.Durability.

Finding out which buying needs are most important to your customers will allow you to match these needs to the benefits of your products. For example, a customer’s buying need might be for comfort and economy - “This mobile phone has dual sim capability with a convenient size, so therefore will be extremely comfortable”

Customer expectations

The customers will have differing needs and wants, however customers have common expectations. The importance of these expectations may vary, depending on the type of product or service they require.

Common expectations are:

• Service
Customers expect a level of service that they think is appropriate for their type of purchase. Someone who makes a small, spontaneous purchase may have a lesser service need that a customer who makes a large purchase.

• Price
The cost of everything we purchase is becoming increasingly important; therefore the price component becomes a vital issue. The temptation for a business to compete on price is financially dangerous. It is a practice that should be avoided unless you have set out to be a ‘discounter’.

• Quality
Customers have expectations of quality and durability. They are less likely to question price if they are doing business with a company that has a reputation for quality.

• Action
Customers need action when a problem or question arises. Everyone has a need for recognition and likes to be treated as a ‘priority’.

In short, if you want to develop a new product or service, exploratory market and customer research should be an essential and continuous component of the process. It provides the foundation and platform for effective idea generation and creativity management. "It describes customer or consumer needs, wants, gripes, complaints, and problems that each have about the performance of a certain activity, function, process, life event, or product.

8. Determine the steps for product analysis and synthesis

February 10, 2014 legend

Product Analysis

Every product is designed in a particular way - product analysis enables us to understand the important materials, processing, economic and aesthetic decisions which are required before any product can be manufactured. An understanding of these decisions can help us in designing and making for ourselves.

Product analysis can take different forms but in general it means asking questions about a product and forming answers. It can mean experts analyzing a product or members of the general public or potential customers/groups of people. Product analysis can take place at almost any stage of the design process.

Product analysis can be carried out by:
1.An individual product being analyzed.
2.Alternatively a number of similar products can be compared with each other using the same criteria.

THE PURPOSE OF PRODUCT ANALYSIS

A product may need analysing by a potential customer to help him/her decide whether it is worth buying.

A product may need analysing so that the design can be improved.

Sometimes a prototype or model may be analysed. In this way improvements can be made before the full sized, costly product is manufactured.

CRITERIA OF PRODUCT ANALYSIS
When analysing a product, first prepare a list of questions, this is known as Criteria. For example, the criteria listed below could apply to a mobile phone when it is being analysed.

• ERGONOMICS

Is the mobile the right size (height, length and width)? Will this make it uncomfortable for the customer?

These things need to be considered while analyzing the product in ergonomic point of view.

• COST

How much will it cost to manufacture the product and how much will it sell for in the shops?

• AESTHETICS

Does the product look good? Is it stylish?

• CLIENT REQUIREMENTS

Is the product what the customer wants? What changes are required to make the product suitable for the client/customer? Does the customer like the product?

• HEALTH AND SAFETY

Is the product safe? Does it fulfill Health and Safety Laws?

Product analysis can seem to follow a fixed pattern:
   1. Think about the design from an ergonomic and functional viewpoint.
   2. Decide on the materials to fulfill the performance requirements.
   3. Choose a suitable process that is also economic.

Product Synthesis

The process of developing the product for satisfying the design concepts and requirements is known as Product Synthesis. Five steps in the Product Synthesis is given as below

1.Idea Generation
• brainstorming - thinking about it
• creating a new product based on some observed need
• thinking of a new product based on some accident or chance circumstance

2. Screening
• getting opinions from
       o employees
       o potential customers
       o media
       o government
• what are the weaknesses of existing products that are similar
• is there any competition for a new product
• What are the industry sales and market trends the product idea is based on

3. Idea Evaluation / Concept Development

• estimate costs, revenue, profit,
• do market research
• target market segmentation
        o describe the main group of people who will be the first customers


4. Development of Product / Business Analysis

• physically design and manufacture the product
• estimate likely selling price based upon competition and customer feedback
• estimate sales volume based upon size of market
• produce a physical prototype or mock-up
• test the product (and its packaging) in typical usage situations

5. Commercialization

• "make enough to sell"
      o manufacture a large amount to send out to the stores that will stock the items so enough
         inventory on hand for the public to buy

• launch "promotion campaign"

7. Discuss the advantages of CAD. How CAD is different from CAM? Illustrate how design process is made simple with a CAD workstation?

February 10, 2014 legend

COMPUTER AIDED DESIGN (CAD)

It is the use of computers to assist in the creation, modification and analysis of a product plan. CAD is a technology that interrelates with so many of other production systems.

Advantages of CAD

1.Improved Productivity
2.Better costing
3.Fewer errors in numerical control programming
4.Reduced tool costs
5.Possibility of easy modifications
6.Better design for manufacture
7.Improved design accuracy
8.Operation at optimal conditions

COMPUTER AIDED MANUFACTURING (CAM)

It is the use of computer systems to plan, manage and control the operations of the manufacturing plant.

Both CAD & CAM systems are now widely used and have transformed much of our country's manufacturing processes. CAD and CAM are fundamentally different.

• In product development, computer-aided design (CAD) automates the design process while computer-aided manufacturing (CAM) automates the manufacturing of CAD-generated product designs.
• The use of CAD then led to the use of CAM, which utilizes data from CAD generated prints to manufacture a part.
• While CAD defines design features, CAM identifies manufacturing features. In other words, with CAD systems, you are creating something digital—the product's computer image—and with CAM, you are creating something physical—the actual product.
• Workflow and time are not important factors in CAD, while CAM is concerned with workflow because the sequence in which various processes are carried out can be crucial.
• CAM is almost effortless. CAD you need to be around all the time.
• CAD Software examples = AutoCAD, Pro-Engineering, CADKEY, Pro-CAD, Turbo-CAD, Visio.
CAM Software examples = SmartCAM, Master CAM, BOBCAD

CAD WORKSTATION

Need for CAD

The 3 primary phases of the product design are
1.Product identification
2.Design and Optimization engineering
3.Drafting

How CAD helps in each of these is mentioned as separate paragraphs below.

Product Concept Development is aided in CAD modeling. A large no. of alternative designs can be generated on the computer screen and the best one out of this can be selected using CAD.

Design and Optimisation done on a CAD terminal can be explained with an example. Proposed product is divided into triangular shaped elements. The effect of loading the structure is seen, deflections & stresses at various nodal points are defined by the vertices of the triangle. Stress concentrated points can be displayed through colour graphics.

Drafting can be performed effectively on a CAD terminal. Any line drawing can be done and stored/displayed by the computer on the CRT screen.

ROLE OF COMPUTER IN DESIGN PROCESS

The design related tasks performed by modern CAD system can be grouped into 4 areas.

1.Geometric Modeling
    It involves computer compatible mathematical description of geometry of an object, using this images of objects are displayed. It can be manipulated on a graphics terminal from CPU of CAD s/m. Different types of commands are used to generate basic geometric elements like line, circle, to accomplish transformations like rotation, scaling, to join various elements to give desired object. In this objects are represented using wireframe, surface, solid models.

2.Engineering Analysis
     Some kind of analysis is required in the formulation of any design project.   Analysis can be stress-strain calculations, heat transfer computations or use   of differential eqns to describe dynamic behavior of s/m being designed.   The computer can be used to assist this work.

3.Design Review & Evaluation
      The accuracy of the s/m can be checked conveniently on graphics terminal. Dimensioning, tolerance routines are there to reduce errors. The designer can zoom in on any details & closely scrutinize the magnified image. Animation, Gear simulation, tooth hole checking etc can also be done which helps in the evaluation process.

4.Automated Drafting
This procedure helps in saving lot of time & labour.Computer aided drafting is known as Design workstation. CAD workstation is the s/m Interface with the outside world. A good CAD workstation must accomplish 5 functions. They are:
a.Interface with the CPU of the computer
b.Generate a steady graphic image for the user
c.Provide digital description of the image
d.Be user friendly
e.Translate computer commands into operating function.

BLOCK DIAGRAM OF A CAD WORKSTATION

Sunday, 9 February 2014

6. Discuss the target specification steps?

February 09, 2014 legend

The target specifications are established after the customer needs have been identified but before the product concepts have been generated and most promising one(s) selected.

The process of establishing the target specification contains four steps:

1. Prepare the list of metrics.
2. Collect competitive benchmarking information.
3. Set ideal and marginally acceptable target values.
4. Reflect on the results and the process.

Step 1: Prepare the list of metrics

A simple needs-metrics matrix represents the relationship between needs and metrics. The row of matrix corresponds to the customer needs, and the columns of the matrix correspond to the metrics. A mark in a cell of the matrix means that the metric associated with the cell is related.

Step 2: Collect competitive benchmarking information

A competitive benchmarking chart will help to give information on competing products and thereby takes positioning decisions. The columns if this chart corresponds to the competitive product and the rows are the metrics established in step 1.For each competitive product, the values of the metrics are simply entered down a column.

Example of List of Metrics

Metric No:	Need No.	Metric	Importance	Units

Step 3: Set ideal and marginally target values.

In this step, the team synthesizes the available information in order to actually set the target values for the metrics. Two types of target values are useful: an ideal values and a marginally acceptable value. The ideal value is the best result the team could hope for.

The marginally acceptable value is the value of the metric that would just barely make the product commercially visible.

There are five ways to express the value of the metrics.

At least X
At most X
Between X and Y
Exactly X
A set of discrete values

Step 4: Reflect on the result and the process

Reflection after each iteration helps to ensure that the result are consistent with the goals of the project. Once the targets have been set, the team can proceed to generate solution concepts. The target specifications then can be used to help the team select a concept and will help the team know when a concept is commercially viable.

Benchmarking Chart Example

Metric No:	Need No.	Metric	Importance	Units	Competitive Product 1	Competitive Product 2

5. Define Science, Engineering & Technology. How requirement analysis of an electronic product is done?

February 09, 2014 legend

Science :

•Knowledge attained through study & practice.
•Derived from the Latin word ‘scientia’ means ‘knowledge’.
•Uses observation & experimentation to describe & explain natural phenomena.
•Often describes any systematic field of study or the knowledge gained from it.
•It seeks to explain the natural events in a reproducible way.

Technology :

•Originated from Greek word ‘technologia’.
•Scientific method & material used to achieve a commercial objective.
•Use & application of knowledge to attain some practical result.
•Consequence of science & engineering.
•Emphasis on a specific area of expertise.

Engineering:

•Application of scientific & mathematical principles to practical ends.
•Includes the ‘economic usage of natural resources’ also.
•Typically a goal-oriented process.
•Use result & techniques from science & technology.

The distinction between science, engineering and technology is not always clear. Science is the reasoned investigation or study of phenomena, aimed at discovering enduring principles among elements of the phenomenal world by employing formal techniques such as the scientific method .Technologies are not usually exclusively products of science, because they have to satisfy requirements such as utility, usability and safety

REQUIREMENT ANALYSIS.

•Analysing various needs of the customer so that those who really design the products ‘fully understand’ the actual needs of the customer.

•Identifying customer needs.
      ☞ 2 types of customers :
                   1.Lead users : experience new needs, ahead of most customers, and need innovations.
                   2.End user : typically the normal user who just uses/ consumes the product.
       ☞ The process of identififying customer needs includes 5 steps :
                   1.Gather raw data from customers.
                       o Involves contact with customers & experience with the use-environment.
                           o 3 methods commonly used :
                                 → Interviews
                                 → Focus groups: a moderator facilitates a 2 hour discussion with a group of
                                       8-12 customers.
                                  → Observing the product in use.
                           o Documenting interactions with customers.
                                  ♦ 4 methods commonly used :
                                       → Audio-recording.
                                       → Notes.
                                       → Video recording.
                                       → Still photography.
                  2.Interpret the raw data in terms of customer needs.
                           o Customer needs expressed as written statements called ‘need statement.
                  3.Organize the needs into a hierarchy.
                           o Need statement classified into
                                       → Primary needs : Most general needs.
                                       → Secondary needs: needs in more detail.
                           o Procedure :
                                       → Print / write each need statement on a separate card or self stick note.
                                       → Eliminate redundant statements.
                                       → Group each cards according to the similarity of needs they express.
                                       → For each group, choose a label.
                                       → Consider creating supergroups consisting of 5 groups.
                                       → Review & edit the organized need statements.
                 4.Establish the relative importance of the needs.
                           o Done through ‘survey’.
                                       → Can be done in person, telephone ,e-mail etc.
                           o Survey-responses used to assign to establish the relative importance of needs.
                 5.Reflect on the result & the process.
                           o Final step.
                           o Verify that have gone in the right direction through interactions with customers.

These steps helps in :

o Establishing product specifications.
o Generating product concepts.
o Selecting a product concept for further development.

4. In order to launch a new electronic product which is no-existing in the market, suggest the steps to be followed from the development of your idea to the final implementation of the product?

February 09, 2014 legend

In order to design a product which is not existing in the market, we have to consider many factors and then implement it in a sequential way.

Basically in product design , we’ve 5 different product-levels. They are:
• Core benefit
• Generic product
• Expected product
• Augmented product
• Potential product.

Core benefit:

• The essential theme of the product.
• Represents the fundamental service of benefits.
• Derived from the consumers need.
• Decisions regarding product should begin with this stage.

Generic product:

• Second level.
• Basic version of the product.
• Typically a rudimentary product.

Expected product :

• Third level.
• Contains the set of ‘attributes & conditions’ that buyers normally expect.

Augmented product :

• Fourth level.
• Includes ‘additional services & benefits’ that distinguish company’s offering from competitors’ offering.

Potential product :

• Top level.
• Includes all the’ augmentations & transformations’ that product light undergo in the course of time.
• Attempts to satisfy all the consumers.

When such a ‘product design ‘ phase is completed, we undertake the real ‘design process’.

Design process.

The design process should consider both the users & transform their needs into a product satisfying these needs.
The design process is a step-by-step process having 6 major levels.

To know these 6 steps in detail click here

Besides all these, the designers and manufacturers should have a clear picture about the life-cycle of the product would be. Such an idea will maximize the efficiency and life of the product.

A typical plot indicating the product life-cycle is shown. It has ‘production /sales’ as y-axis & ‘time’ in the x-axis.

As seen above , the entire cycle is divided into 4 major stages.
1.Introduction.
2.Growth
3.Maturity
4.decline

Introduction

initial increase in production.
includes taking ‘patents’ for the product.
Establishing brand-names.
Pricing.
Trademark.

Growth

More quick production- increase than in the introduction phase.
extra features added to captivate customers.
Advertisements to improve sales.
More distribution channels (market places)

Maturity

Obtained Optimum production.
Add up some extra-features.
Reduce price.
Differentiate the product from the competitor’s product.

Decline

Maintain the product by adding new features.
Find new users.
Discontinue the product or sell it to any willing firm.

Hence by considering all these major steps, a non-existing product can find its way to the market and become a successful product.

Electronic Product Design notes study material index

February 09, 2014 legend

Hi I am sharing my lecture notes in Electronic Product Design,this study material is as per CUSAT syllabus also useful for all other universities

Check back frequently, and bookmark this page , more questions and answers will be added.

1. What are the various dimensions of electronic product design?

2. Explain the industrial design process in detail?

3. Describe engineering process for real-life problem solving?

4. In order to launch a new electronic product which is no-existing in the market, suggest the steps to be followed from the development of your idea to the final implementation of the product?

5. Define Science, Engineering & Technology. How requirement analysis of an electronic product is done?

6. Discuss the target specification steps?

7. Discuss the advantages of CAD. How CAD is different from CAM? Illustrate how design process is made simple with a CAD workstation?

8. Determine the steps for product analysis and synthesis

9. Identify how an electronic product should be launched & explain how customer needs are identified for new product.

10. Explain why Timing Analysis is important in the product design process. Explain any one Timing Analysis Tool

11. What are the Product Design Specifications (PDS) to develop a new electronic product?

3. Describe engineering process for real-life problem solving?

February 09, 2014 legend

Life is a result of multiple events & needs.

Engineers design various products to:

1.Satisfy the needs of the customers
2.To solve the common problems that people face.

Hence, it is essential to know the engineering process for solving real-life problems.

The needs of the customer increases as technology advances.

Furthermore different customers have different needs / requirements

Example 1: A lead user, who has significant contact with the product designer, will definitely have needs different from an end user who merely uses/consumes the product.

Example2: requirement of an end user will be: touch screen, light weight etc. But the requirement of a lead user will be: 4-point multitouch screen, DirectX9 rendering-capable GPU etc.

Thus the design process should consider both the users & transform their needs into a product satisfying these needs.

The design process is a step-by-step process having 6 major levels.

Consider an example of a ‘mobile phone’.

Design Brief:

• First phase of design process.
• Typically a ‘statement of intent’ ie a statement which tells what the designer intend to make.
        o In this case, the statement would be, “We will design and make a mobile phone.”
• One should not start designing just after this statement since it doesn’t have enough information/idea about the product.

Product Design Specification (PDS):

• Most important stage of design process.
• What ‘exactly’ we design.
• “A document listing the problem in detail.”
        o Need true understanding of the “actual” problem.
        o Example: whether one should design a ‘feature phone’ or a ’smart phone’.
             → If smart phone, what all features should be included ( according to requirement)
                   Ex: whether to include features such as all-day battery life, 3G connectivity,
                         high-precision GPS etc.
• Requires good amount of’ interaction and analysis ‘with customer & marketplace.
• Constantly refer this document to ensure whether designs are appropriate.
• Also include a detailed study about the competing products & all important discoveries related to the intended product.

Concept Design :

• Developed from PDS.
• Producing an ‘outline’ of the key components & their arrangements.
        o Ex: typically a block-diagram showing the various components in the phone & their
                   interconnections.
• Also, consider other factors like manufacture, sales, transport etc.
        o To eliminate problems that may occur at these stages.

• Try-out drawing different feasible concept designs.
        o Evaluate them & select the most appropriate design.

•Two-step process :

☞Concept Generation
        • Different ideas can be sketches or annotated( jotted down in form of points )
               o Provide easy & effective communication between other member-designers.
        • Various techniques to aid the development of a new concept.
               o Ex: brainstorming
        • Put forward / list as many ideas discuss each of them identify a potential idea (concept) go
           forward with this concept.
☞Concept Evaluation
         • Evaluating the concept by viewing it various angles / perspectives.
         • Various methods of evaluation prevalent
            → ‘Matrix evaluation’ is one such useful technique.
                       ♦ Table drawn listing the important features.
                       ♦ Products listed across the table.
                       ♦ ‘Benchmark concept’ is the ‘reference concept’.
                       ♦ Other concepts compared with benchmark concept.( by assigning points and
                            weights)
                       ♦ The better concept is developed further.

Detail design:

• Chosen concept design designed in detail.
• All dimensions and specifications mentioned in this stage.
        o Length, breadth, thickness, battery-size etc for the mobile phone.
• A detailed drawing of the design is made.
        o Ex: a circuit diagram developed from block diagram mentioning the exact values of all the
           components used.( like value of resistors ,capacitors etc)
• Produce prototypes to test ideas.
        o To ensure the feasibility before applying all resources for manufacture.
        o Involve interaction with manufacturer.

Thus the transition from ‘need for a product’ ‘specification of the product’ have been attained.

Manufacturing & Testing:

• Product now ready for mass-production.
• Each manufactured product to be tested to ensure proper functioning.

Sales :

• Product to be transported ‘safely’ to selling-outlets.
• Ensure sufficient numbers of pieces are distributed to avoid shortage.

It is concluded that a product can become ‘successful’ if the above-told strategies are performed efficiently.

Thus, the engineering process can be applied to solve real-life problems.

2. Explain the industrial design process in detail?

February 09, 2014 legend

Industrial Design (ID) is the professional service of creating and developing concepts and specifications that optimize the function, value and appearance of products and systems for the mutual benefit of both user and manufacturer.

The industrial design process consists of the following phases:

1. Investigation of customer needs

2. Conceptualization

3. Preliminary refinement

4. Further refinement and final concept selection

5. Control drawings

6. Co-ordination with engineering, manufacturing and vendors

☞1.INVESTIGATION OF CUSTOMER NEEDS

Since industrial designers are skilled at recognizing issues involving user interactions ,industrial design involvement is crucial in the needs process .For example ,for a new medical instrument, the team would study an operating room ,interview physicians .While involvement for marketing, engineering and industrial design leads to a common ,comprehensive understanding of the customer need.

☞2.CONCEPTUALIZATION

Once the customer needs and constraints are understood, the industrial designers help the team to conceptualize the product. Here attention is for finding solutions to the technical sub functions for the product.

The industrial designers concentrate upon creating the product’s form and user interfaces. Industrial designers make simple sketches, known as thumbnail sketches, of each concept. These sketches are a fast and inexpensive medium for expressing ideas and evaluating possibilities.
The proposed concepts may then be matched and combined with the technical solutions under exploration. Concepts are grouped and evaluated by the team according to the customer needs, technical feasibility, cost, and manufacturing considerations.

☞3.PRELIMINARY REFINEMENT

In this stage, industrial designers build models of the most promising concepts. Soft models are typically made in full scale using foam or foam core-board. These models allow the development team to express and visualize product concepts in three dimensions. Designers will build as many models as possible depending on time and financial constraints.

☞4.FURTHER REFINEMENT AND FINAL CONCEPT SELECTION

At this stage, industrial designers often switch from soft models and sketches to hard models and information – intensive drawings known as renderings .Drawn in two or three dimensionally ,they convey a great deal ,of information about the product .The final refinement step before selecting a concept is to create hard models. They are made from wood, dense foam, plastic or metal, are painted and textured, and have some working features such as buttons that push or sliders that move. Since it is costly, a product development team has the budget to make only a few.

☞5.CONTROL DRAWINGS

Industrial designers complete their design process by making control drawings of the final concepts. These drawings document functionality, features, sizes, colours, surface finishes and key dimensions.

☞6.CO-ORDINATION WITH ENGINEERING, MANUFACTURING AND VENDORS

The designers must continue to work closely with engineering and manufacturing personnel throughout the subsequent product development process. Some industrial design consulting firms offer quite comprehensive product development services, including detailed engineering design and the selection and management of outside vendors of materials, tooling, components and assembly services.

The benefits of using industrial design process include increased product appeal and greater customer satisfaction through additional features, strong brand identity and product differentiation. Industrial design helps to establish a corporate identity. Industrial design determines a product’s style, which is directly related to the public perception of the firm.

The industrial design process if properly implemented will provide all of the above mentioned features.

1. What are the various dimensions of electronic product design?

February 09, 2014 legend

Lets explain the dimensions of electronic product design

Design is the process by which the needs of the customer or marketplace are transformed into a product satisfying the needs.

So the various dimensions of electronic product design are

(a) Scientific design
(b)Industrial design
(c)Engineering design

Scientific design

                  Scientific design involves different stages. The existing knowledge is the key factor and forms the base of the design process. The existing knowledge is then transformed into a hypothesis from which the evolution of the new product has been realized. The next phase is logic analysis. From the analysis the experiments are performed. The final stage of the design is called proof.

Industrial design

                 The industrial designer’s society of America (IDSA) defines Industrial design as “the professional service of creating and developing concepts and specifications that optimize the functions, value, and appearance of products and systems for the mutual benefit of both user and manufacturer”. Industrial design starts form the conceptualization phase. From concepts, it develops into structures and configuration. The next phase involves optimization analysis. The design form the conceptual level may go into detailed from design .The detailed anatomy of the structures is prepared. The design is confirmed in accordance with the thermal and EMC requirements. Industrial design needs development drawing, the integration documents and details of the product.

Engineering design

                          At the beginning stage of the product, engineering design has much importance than industrial design. Because the product priority factor involves the measures of intrinsic relationship between man and the product. Engineering design is associated with number of factors like circuit design, software development, design for safety, design for assembly, design for cost, choice of materials etc.Engineering design methodologies have prime importance in the initial stage of product development. The integration of functional parts and experiments are needed in the engineering design stage. The necessary packaging and interconnections are determined as per the requirement.

Saturday, 8 February 2014

4. what are the applications of microwaves.

February 08, 2014 legend

Microwaves have a broad range of applications. The applications are in the areas listed below.

1.Telecommunications
☞ Intercontinental telephone and TV
☞ Space communication (Earth to space and space to earth)
☞ Radio astronomy
☞ Naviagation
☞ Wireless mobile communication

2.RADARS
☞ Detect aircraft
☞ Track and guide supersonic missiles
☞ Observe and track weather pattern
☞ Air traffic control
☞ Police speed detector

3.Commercial and industrial applications
☞ Microwave oven
☞ Biomedical applications
☞ Food processing industry

4.Electronic warfare, spread spectrum systems

5.Identifying objects / personnel by non contact method

Thursday, 6 February 2014

3. Explain the advantages and disadvantages of Microwaves.

February 06, 2014 legend

Advantages of Microwaves:

✿ Microwave frequencies are extremely high.Hence they offer extremely high Bandwidth for communication channels. For example, a typical microwave communication channel can carry 4000 audio or 4 video channels. Only, optical communication channels have more Bandwidth than this.

✿ They propagate along line-of-sight paths through troposphere, where loses that we face in the ground-wave and sky-wave propagations are absent or minimum. Therefore, for transmission of signals, the transmitter power used will be much smaller than that required in the cases of the ground-wave and the sky-wave propagations. (With microwave frequencies, even a 100W transmitter is considered as a high power transmitter.)

✿ Antennas required at microwave frequencies are much smaller in size than those used at lower frequencies. Because of this, and because of the low losses, microwave frequencies are used in modern mobile communications system.

✿ Usually, noise interference from disturbances such as automobile ignition switches will not affect microwaves as they occur at much lower frequencies.

✿ Microwave communication is a point-to-point communication scheme through cables or antennas. Hence, tapping is difficult at these frequencies as they require highly specialized and costly equipments for carrying out those tasks.

✿ Microwave tend to flow through the surface of conductors due to what is known as skin effect. This in turn has been effectively used in a heating process called induction heating. Induction heaters are being widely used in the manufacturing of blades, knives, semiconductor chips etc.

✿ Since microwaves are also AC, they can flow through capacitors, microwave frequencies heat up the dielectric material in between the capacitor plates. This type of heating is called the dielectric heating. This is the principle of operation of modern microwave ovens.

Disadvantages of Microwaves:

✿ A major disadvantage of microwaves is the nature of propagation itself. As has been seen, microwaves propagate in the line-of-sight mode. In this mode, microwave frequencies travel in straight-line paths, Which are limited by the horizon. The maximum range of transmission, hence, is limited to a radius of 80 km around a transmitter. For long distance transmission, we must use repeating stations at approximately 80 km interval.

✿ Microwave transmission towers are complex in construction, and are highly expensive.

Wednesday, 5 February 2014

2. List various Microwave frequency bands as table

February 05, 2014 legend

The various microwave frequency bands are listed below as a table :

Microwave Letter Band Designations
Band Designation	Frequency Range (GHZ)
L	1 - 2
S	2 - 4
C	4 - 8
X	8 - 12
Ku	12 - 18
K	18 - 26.5
Ka	26.5 - 40
V	40 - 75
W	75 - 110
D	110 - 170

Tuesday, 4 February 2014

1. Why Microwave is called Microwave?

February 04, 2014 legend

Microwaves are a form of electromagnetic radiation with frequencies ranging between 300 MHZ and 300 GHZ (some sources say from 1 GHZ to 1000 GHZ for eg: Somanathan Nair textbook, In all cases microwave includes the entire SHF band).

The prefix "micro-" in "microwave" is not meant to suggest a wavelength in the micrometer range. It indicates that microwaves are "small" compared to waves used in typical radio broadcasting, in that they have shorter wavelengths.

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