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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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### What differences in terms of fields does a grounded metal and an unconnected metal object have

I previously asked a question regarding absorption and reflections of waves to metal. But id like to know the differences that say a PCB metal pour that is connected to a signals return path, and a ...
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### Transmission Lines and Waveguides - How to calculate Intrinsic Impedance?

I have come across a problem when calculating the attenuation due to conductor losses for circular cross sections: A circular copper waveguide has a radius of 0.4 cm and is filled with a dielectric ...
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### Transmision and coupling coefficient in waveguide and ring resonator

A simple ring resonator with a bus waveguide is described by: \begin{pmatrix} B \\ C \end{pmatrix} = \begin{pmatrix} t & \kappa \\ -\kappa^* & t^* \end{pmatrix} \begin{pmatrix}...
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### coplanar waveguide impedance calculation and tolerance

The Ublox Sara R5 System Integration Guide I am following states that a 50 Ohm antenna waveguide design is recommended and provides a couple example designs that achieve this using FR4 dielectric. ...
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### Identifying monopole antenna with ground connected coil

I can’t find any information on what this design of antenna is called, it has a monopole wire connected to the signal pin of an SMA connector, the coil is connected to ground. The larger diameter ...
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### Using microwaves to dry a small sample of material - best method?

We have a requirement to use microwaves (no choice here) to dry a small sample of material with a mass not exceeding one gram. It will be placed in a small sealed steel enclosure. First thoughts were ...
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### From the perspective of a progressive wave, what is lumped impedance? [closed]

This question asks about the meaning of lumped impedance in traveling wave theory. Should lumped impedance be viewed as something like a point charge, a point mass, or a direct delta function? When a ...
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### Conformal Mapping in Electrostatics: t-plane

In the paper 'Extension of the application of conformal mapping techniques to coplanar lines with finite dimensions' the author uses the t-plane as a intermediate step for calculating the capacitance ...
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### Interruption in waveguides

I want to fabricate a PE waveguide.I deposited a layer of aluminum with a thickness of 180 nm on Lithium niobate.I lithographed the design of the waveguide,After developing photoresist and etching the ...
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### Which stackup to choose for JLPCB FR4 up to ~10GHz

I am aware that 10GHz on FR4 is not ideal, but this is an hobby project and I can tolerate some losses. The 10GHz on the PCB is minimal (probably only a short coplanar waveguide or microstrip with 2 ...
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### Ansys AEDT and Icepak Simulation

I have designed slotted coax cable based waveguide and FR4 is not getting any heat and even the coaxial cable does not get any heat which I do not understand why. E field as follows, ports include 2kW ...
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### Phase velocity non-TEM transmission line

Assuming that a transmission line operates in a TEM or quasi-TEM mode, the phase velocity can be determined from the line parameters (R,L,C,G per meter assuming the RLCG model of a transmission line). ...
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### Unexpected low characteristic impedance using the JLCPCB impedance calculator

I'm currently designing a PCB that is intended to fan out the 38 pins of a MICTOR connector to every other conductor of an 80-conductor ribbon cable (The PATA type one, that is AWG30 wires with a 0....
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### Circular waveguide excitation for TE11 coefficients

As we can see below, the theory says that A,B coefficients depend on the excitation. I have simulated a circular waveguide. How do I need to excite my waveguide so I will see the A and B coefficients ...
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### Interference of RF currents with a combiner

I am trying to understand what happens to 2 RF currents flowing in separate planar waveguides (such as microstrip lines), when combined with a power combiner. More specifically, will they interfere, ...
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### Could a DIY 1 kW portable version of the military non-lethal microwave beam active denial system (ADS) be made?

How would one create a portable 1 kW microwave emitter that projects out a 95 GHz beam to about 5 - 10 feet? What kind of components would be required? I recently came across this fascinating video ...
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### How to generate microwave band frequencies like 85GHz? Is there a DIY device or parts kit to do this? [closed]

Let's say I want to build a device that generates and sends out a microwave of some arbitrary specific frequency to a short distance, say 1 - 2 feet. For example, 95 GHz. Is there a straightforward ...
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### Need help using RF transceiver with RF amplifiers

I'm trying to use the STM32WLE5C8 SoC that is both a microcontroller and an RF radio. For my project I will be using the radio in the 800 - 900 MHz band (high-band configuration for this radio). I ...
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### Help with understanding waveguide dimensions for a pyramidal horn antenna

I want to build a pyramidal horn telescope as a science project but I’m having some trouble understanding the waveguide dimensions. This documentation lists the dimensions of a paint thinner can be ...
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### Minimum trace distance when using a via fence in a waveguide

I am trying to route several high speed JESD204B signals (up to 12GHz) to a connector and there is very small area for them. The manufacturer design note (p.113) recommends to route those signals on ...
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### Effect of surrounding material on microstrip impedance?

If you were to have a microstrip transmission line PCB trace, which then had a dielectric material run completely on top of the PCB track coverlayer. Would this surrounding material affect the ...
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### How do I find out the dimensions of a rectangular waveguide given the frequency I want to operate it at?

I want to design a horn antenna to detect the 21 cm hydrogen line. I know how to optimize the antenna dimensions by taking into account some functions that approximate the phase errors and ...
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### Is there a standard that describes the term "coplanar waveguide"?

I look at IEC60050 "International Electrotechnical Vocabulary" standard at section 726 "Transmission lines and waveguides" and searching on the word "coplanar" gives me ...
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### Why do dielectric waveguides support hybrid modes and metallic waveguides do not?

Can anyone explain to me qualitatively why dielectric waveguides (core and infinite cladding) support hybrid modes (E_z and H_z components in the guided wave), while metallic waveguides cannot? I am ...
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### The field in a waveguide at exactly the cut-off frequency

Can anyone explain to me qualitatively, what kind of field exists inside a waveguide at EXACTLY the cut-off frequency? I would be grateful if an explanation was given about waveguides with metalic ...
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### How can I tell whether a waveguide supports hybrid modes or not?

When studying metallic waveguides, it was taken for granted that the TE and TM (and potentially TEM) formed a complete set, that is, any electromagnetic field in the waveguide could be written as a ...
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### I need help trying to set up a rectangular waveguide in HFSS,

Task: Setup a rectangular waveguide in HFSS using four perfect E boundaries on the side faces of a box and waveports on the end faces of the box. Set up your dimensions so that at the lowest frequency ...
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### Where is the azimuth and radial direction on the mode plot

Hello the photo bellow presents TE01 mode. Where on the plot can i see the azimuth and the radial directions? Thanks.
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### How to interpret waveguide multi-mode S-parameters in CST

I have a cylindrical waveguide which is excited with two modes in each ports as shown bellow. However I cant see the meaning of S-params shown bellow. photo one shows total isolation(-100dB) While ...
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### Why is a microwave oven equipped with a waveguide? [duplicate]

In a microwave oven, the magnetron connects to the waveguide.  Magnetrons produce microwaves, which are guided into the cooking chamber by waveguides. Why don't we directly connect the magnetron to ...
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### Waveguides and optical fibres

Why at microwave frequency we prefer rectangular waveguides while at optical frequency circular waveguides (i.e. optical fibres). Can we have rectangular optical fibres.
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### How to imagine the mathematical expression in the waveguide?

Below we see an example expression for the E-field. It has three components: polarization of the field propagation direction standing wave pattern In the photo below of the field "L" has ...
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### What is a guided mode?

I am currently reading my text, for my electromagnetics course, and we are discussing guided waves. The text casually mentions the term "guided modes", and never really defines what that ...
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### Different 50Ohm-matched condition for different length of metamaterial waveguide

Based on coplanar waveguide, I am designing a meta-material waveguide by inserting lumped-element inductors along the center line. Here are some parameters: Target frequency: 10-20 GHz Size of lump ...
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### What is the impedance looking into a length of coaxial cable that is short-circuited at the far end and a half wave-length long?

What is the impedance looking into a length of coaxial cable that is short-circuited at the far end and a half wave long? I have been told that this the the basis of what is known as a wave guide &...
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### Dielectric slab waveguide

let's consider the so called dielectric slab waveguide (references for image and equations: here, page 53): I do not know much about it, I know only that it is a planar guiding structure which is ...
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### Elliptical polarization and waveguides

It is known that a generic harmonic electric field which propagages in free space has an elliptical polarization (if you want to read the proof, look at this, slides 72 - 99). My question is: what ...
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### Engineering very high impedance resonator with coplanar waveguides

I have very little knowledge of electrical engineering, so please understand if my questions are somewhat trivial. I have read that a coplanar waveguide (CPWG) acts as a lumped LC oscillator circuit, ...
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### Can I get the S21 parameter from a one-port open, short and load reading?

I am currently working with a custom rectangular waveguide, which has one port abled to connect to a VNA,(call it port a) but the other side cannot, (its part of a bigger system but for now its only ...
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### Designing waveguide based structure using cst

I am going to start designing waveguide based circulator , hybrid and loads using cst or ansys workbench. I am quite familiar with the design of microstripline and stripline based systems using ADS. ...
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### Shape of waves in waveguide

What is actually going on in waveguide when the wave is passing through it ? If I am not mistaking , the plane waves are "fed" to the waveguide and there is a cutoff freq above which the waves can ...
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### Evaluation of the dominant mode in a waveguide

In a waveguide, the dominant mode is defined as the propagation mode with the lowest cutoff frequency. Now let's consider a structure in which the lowest cutoff frequency occurs for two different ...
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### Geometric spreading of an impulse antenna

I am new to radar and curious about the geometric spreading in free space. I set up an air-coupled antenna about a half meter above the ground, with a large PEC on the ground. Then I adjusted the ...
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### Waveguides Equivalent Circuits

I was reading in a book how to derive the equivalent circuits for TE, TM, TEM modes of a generic ideal (without losses) waveguide. After some computations, it found this equivalent circuit for TE ...
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### 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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### 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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### 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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### 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 ...