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Questions tagged [waveguide]

A waveguide is a physical structure that guides electromagnetic or sound waves. They are most commonly employed at high frequencies such as microwave.

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1answer
38 views

Cut-off frequency in ideal waveguides

it is known that in an ideal waveguide (with a perfect electric conductor and with non-dispersive and non-conductive dielectric) there is a cut-off frequency, for each mode, such that for higher ...
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49 views

Excitation of a resonant cavity

let's consider this picture in which a cylindrical resonant cavity is excited through a waveguide. I have some questions: 1) Why is it called "Magnetic Coupling"? I thought this excitation simply ...
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How to construct an SMA feedline for a horn antenna

I'm constructing an sma coax to waveguide transition for a horn antenna. Here's a cross-sectional view of what the device will look like I can 3d print the waveguide portion (I use a conductive paint ...
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2answers
98 views

Impedance mismatch vs Signal attenuation

I'm currently designing a 50Ω grounded coplanar waveguide (GCPW) which connects an antenna to an LTE modem. My question is: does there exist a standard graph/chart that attempts to generalise ...
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Calculating dielectric constant of a dielectric sample placed inside a rectangular waveguide [duplicate]

Im trying to calculate the dielectric constant of a dielectric sample placed inside a rectangular waveguide over a range of frequenices. I used WR90 ( X band ).Using the s parameter data (S11 and S21),...
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1answer
52 views

Can anyone tell me how to find permittivity of a dielectric sample using a rectangular waveguide

Im trying to find the material paramters of a dielectric sample using a waveguide(X band) employing the Transmission/Reflection technique. While performing simulation in CST, how to properly orient ...
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1answer
26 views

Guided propagation in transmission lines

Can you help me on understanding why we may say this transmission line the propagation is guided and there is not any radiation? It is a 2-conductors transmission line, in which the conductors are ...
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2answers
54 views

Considering Moding Issues in High Speed PCB Design

My question is a more generic one. I recently learnt about TE and TM propagation modes in waveguides. This made me think that when designing high-speed PCBs people always talk about matching the ...
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0answers
45 views

Radiation Source placement and waveguide parameters for Horn Antenna

I am designing ("arranging", actually) a horn antenna for a 77-81 GHz Radar. My module has a patch antenna which can't be placed inside the waveguide for some reasons. After the patch antenna, we have ...
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0answers
35 views

Angle of incidence in a waveguide?

I have been searching for a while about how to calculate the angle of incidence for a waveguide. It's a question that I had for a quiz and still no-one my class knows the formula. Could someone give ...
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2answers
46 views

RF Design - Antenna Feed-line Parameters

I am implementing a BLE device with a chip antenna. The device has already been impedance matched to 50Ω and is ready to be connected to the feedline and antenna. The antenna datasheet has a ...
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0answers
31 views

Estimating the effect of dielectric bridges on a coplanar waveguide

I'll start with some context, but feel free to skip to the third paragraph for the concrete question. In the context of superconducting microwave circuits (such as those used in some qubit ...
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1answer
42 views

What is the mode of a square waveguide \$TE_{11}\$ that is deformed into a circle?

I am trying to solve the 2013 paper set by ISRO for electrical engineers. I want some help to solve Question no 17 is correct. So I don't even know how to approach the problem, what will be the new ...
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1answer
173 views

Single-line power transmission of 1MW over 35,000km [closed]

This question posted on the physics stack exchange has not received much attention. I thought the audience here might be more able to answer it. Background A space elevator is mechanism to provide ...
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1answer
286 views

Differential Pair Reference Plane Coupling

I am routing LVDS pair on a flex board. The signal is 264MHz. I used Saturn PCB design to calculate width and spacing between conductors. The targeted impedance for diff pair is 100 ohms, which is ...
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1answer
539 views

Coplanar Waveguide Calculations PCBS, AppCAD v.s. Online calculators

So lately I noticed that the Coplanar Waveguid calculations of AppCAD (http://www.hp.woodshot.com/) did not give the same result as the online calculators do. https://chemandy.com/calculators/...
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1answer
52 views

Frequency response of the waveguide

So, I have signal in the waveguide that is transmitted by two modes of radiation, for which the delay is for example \$\tau_1=6\,\text{ns},\, \tau_2=6.5\,\text{ns}\$, respectively. And the energy ...
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1answer
338 views

Design of cavity filter

I try to design a Chebyshev bandpass filter for 6 GHz as a coaxial cavity filter. I know that the filter can be designed with the aid of the coupling coefficients between the resonators and the loaded ...
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1answer
67 views

Metallic Waveguide Boundary

I've been studying TE and TM modes on waveguides for microwave frequencies. It basically consists on applying Maxwell equations on a rectangular metallic cavity, with infinite length on \$z\$ ...
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2answers
1k views

Standard 2.54/1.27mm pinheader impedance

Note I turned my answer into something of a collection of free impedance calculators.. I was thinking of using one of the most ubiquitous connectors in the world - 2.54mm pin header. The snag here ...
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0answers
69 views

Can I trust these microwave power readings?

So I've got an old Hughes TWT that supplies roughly 20W across the Ku band (12.4 - 18 GHz) that has a waveguide output flange (WR-62). I am "gently re-purposing" it to be driven at a lower frequency (...
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1answer
107 views

Rectangular Waveguide H-Plane Step Discontinuity - Equivalent Reactance for Change in Height

I have been reading Pozar's Microwave Engineering, and in Section 4.6, he goes through the analysis to determine the reactance of a discontinuity between two coupled waveguides. In that chapter, he ...
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2answers
100 views

Phase and group velocity of wave

When an electromagnetic wave enter the waveguide, what is the change in the phase and group velocity that happen in waveguide? Does wavelength or frequency of wave change when it enter the wave guide?...
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1answer
108 views

Analysis of transmission lines and waveguides

While reading the transmission lines in electromagnetic field theory , I observed that while analyzing different transmission lines like co-axial cable, and two wire lines, we are using the electric ...
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1answer
35 views

Antenna CPW internal layer

I see on the internet showing CPW( coplanar waveguide) always placed on TOP layer with ground underneath. This is what I usually do. Is it possible to place a CPW in an internal layer? if so what ...
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1answer
64 views

Scattering parameters of a phase shifter

I connected a phase shifter to a VNA and measured S11 and S21. Upon setting the angle (phase) to a 100 degrees and measuring the phase of S11 I obtained the following graph, whereas theoretically S11=...
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1answer
124 views

What makes the band of an antenna broader than others?

Even though I'm studying waveguide slot antennas, so the examples that I'm going to give are related to this topic, my question covers a wider range of topics. I already know about a couple of things:...
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2answers
2k views

Designing a 50Ω coplanar waveguide on 1.6mm FR4

I'm trying to design a 50Ω coplanar waveguide to connect the output of a LoRa module to a SMD metal antenna. The two images below show the top layer (red) and bottom layer (blue). Vias are green and ...
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0answers
64 views

Waveguide with 3 dielectric sections

The cross sectional dimensions of the rectangular waveguide in the figure are \$a=50 mm, b=25 mm\$. The waveguide consists of 3 sections filled with dielectric materials such that the relative ...
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1answer
344 views

Waveguides question

A rectangular waveguide with dimensions \$a=10cm, b=6cm\$ is filled with dielectric material with an unknown relative coefficient \$\epsilon_r\$. The guide is terminated by an unknown load. It is ...
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2answers
336 views

What are the waveguide modes of twisted pairs as discussed here?

From the recent Lightwave article ASSIA exec touts terabit-speed DSL: In a keynote address delivered earlier this week at the G.fast Summit in Paris, Dr. John Cioffi, chairman and CEO of DSL ...
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110 views

Microwave Waveguide Power Ratio

Had a waveguide system set up similar to picture, to compare measured to calculated power ratio or path loss (differences between positions). With an SWR meter the following was recorded at various ...
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1answer
126 views

Can closed metal box work as a wave-guide for wireless transmitter?

I am using NRF24L01 and ZigBee modules for wireless communication. I kept the modules in the tapered closed aluminum cylinder for sensor data transmission. The signal was being received when the ...
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1answer
1k views

What is the simple meaning of TE10 waveguide [closed]

What does this numeral 10 represents and why do we have TE10 TE11 and then TE20. Where are the rest?
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2answers
575 views

Coplanar waveguide - Calculator question

I was looking for information on coplanar waveguides (curiosity prompted by another question here) and found this calculator. In the description of use, it mentions that the units for the dimensions ...
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1answer
336 views

Microwave Waveguide system tuning

I am going to built microwave system with following system configuration. Power Circuit -> Magnetron -> Wave Guide Coupler -> Isolator -> 3 Stub Tuner -> Applicator. Now, I want to make 3 Stub ...
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1answer
51 views

Group velocity dispersion for coupled waveguide system

I am an EE undergrad currently studying group velocity dispersion (GVD) for coupled waveguides, and am quite confused on the following question: how do you characterize group velocity dispersion for a ...
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1answer
265 views

Why is Kapton film used to hold liquid in waveguide?

I am working on a project similar to the one described in this paper MEASUREMENT OF COMPLEX PERMITTIVITY OF LIQUIDS. Here a Kapton film is used to hold liquids, so that they don't spill. Why is this ...
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2answers
2k views

What are the advantages of CPW over microstrip?

I have to use a coplanar waveguide (CPW) for a project which is going to characterise small amounts of tissue. I have never used CPW before. What are the advantages of using CPW? What would be some ...
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1answer
901 views

RF cable with DC power cable?

I have a satellite communication system at office running on C-band. The C-band is downconverted to L-band and carried to the l-band modem. With this RF coaxial waveguide/cable, +12V DC power cable ...
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1answer
152 views

Coplanar waveguide vs open space?

I'm routing a U.FL connector to a cellular module (Telit GE864). According to this calculator a 1mm track with 0.16mm gaps should provide a 52Ω impedance path to an U.FL antenna connector. A ...
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5answers
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Why are rectangular waveguides not used for inter-city transmission?

Waveguides can transmit very high powers, isolating the signal from external noises and interferences. Besides, waveguides have a very low loss. These capabilities make them an interesting candidate ...
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1answer
377 views

Impedance of waveguides shorter than 1/10 of wavelength

I read already several times that it is a common rule of thumb, that matching the impedance of a waveguide to the external network impedance is only necessary for waveguides longer than 1/10 of the ...
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2answers
320 views

Waveguides: How can you propagate at only one frequency?

In a rectangular waveguide, we know we can find cut off frequency as a function of mode and geometry. Is there a way to design the waveguide so to ensure that we can limit the frequency of ...
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1answer
164 views

Plane wave causing TE mode in waveguide

I've been struggling with a problem given to us during a exercise-session of waveguides. First part of the exercise was calculating the electric field inside of a waveguide in the form of 2 parallel ...
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4answers
16k views

Why is it that a TEM mode propagates in a - Two separate conductor wave guide?

Please someone explain to me in Simple English or Basic equations as to why does a Transverse Electric and Magnetic Modes(TEM) propagate on only two surface Wave ...
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2answers
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Automatic impedance matching in microwave waveguides

I am trying to building a magnetron plasma using microwave magnetron. I now need to build magnetron to antenna link using rectangular waveguide, WR-340. I then found out that it needs to be tuned ...
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1answer
444 views

How are modes generated in a waveguide?

Its related to my previous question Modes in waveguides I have a doubt that how are different modes actually generated? I mean in Digital and Analog communication, we studied how we modulate the ...
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2answers
453 views

Why a wave does not enter a cable? Understanding TDR (Time Domain Reflectometry)

I have been doing some TDR (Time Domain Reflectometry) measures which involves sending gaussian pulses through a cable and measuring the s11 (reflection) parameter. In this measure, I could see that ...
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2answers
2k views

Field Patterns in Waveguides

How are the field patterns for magnetic and electric field obtained using the field equations? What is the intuitive way of understanding and drawing them? I searched a lot regarding the method for ...