Questions tagged [microwave]
Microwaves are radio waves with a frequency from 300MHz to 300GHz which corresponds to a wavelength of one meter down to one millimeter. Often in RF engineering however it is used to refer to a narrower region such as 1 to 100GHz.
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How does a wifi antenna work?
let's consider a common wifi antenna (used in routers) like this:
I don't understand some its basic features:
1) Is it a dipole or monopole antenna? I see only one conductor, so I'd say it's a ...
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2answers
294 views
Transmission lines with same impedance but different dimensions
Suppose we connect two transmission lines with characteristic impedances \$Z_1\$ and \$Z_2\$. The reflection coefficient looking into the transmission line with impedance \$Z_2\$ is
$$
\Gamma=\frac{...
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1answer
24 views
What is beam coupling coefficient for linear beam klystron?
What does beam coupling coefficient exactly tell? For eg. a voltage gain coefficient tells how much times the input was amplified. So what does beam coupling coefficient tell, like does it tell how ...
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2answers
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How reflection occuring in antenna fed by transmission line affects performance?
Transmission line considered is lossless.
Basically the configuration is simple.
For transmitter side : a non ideal source (can be voltage current or power) feeding a transmission line (TL1) with ...
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1answer
92 views
Why aren't antennas placed at the ceiling of a microwave oven
From what I have understand, microwave ovens work by emitting microwave electromagnetic waves from some antenna. Please correct me if I'm wrong.
In my microwave oven I have seen some empty holes at ...
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1answer
43 views
How can a resonator do band-pass filtering?
I've read many times some statements about resonators like this (reference):
Resonant circuits are circuits, which offers a high impedance or low impedance (for parallel and series
resonance ...
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1answer
42 views
Multiple Resonances along a transmission line
in "Lessons in Electric Circuits", VOL III, ChPT 14, all the possible configurations of standing wave for a certain transmission line are shown. For instance, this is the case of a ...
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2answers
57 views
Reference node in a transmission line
in "Lessons in Electric Circuits", VOL III, ChPT 14, there is a SPICE simulation of this transmission line:
The author writes:
Running this simulation and plotting the source impedance ...
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0answers
32 views
Why does the peak power change with the spectrum analyzer's span?
Consider a continuous wave signal being displayed on a spectrum analyzer at f=5GHz. It's a single peak. When I put marker on the peak it shows me the peak measured power. Now when I decrease the span ...
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How to find the distance between two arms of a hairpin resonator?
In this picture I want to find the value of W_cap(the distance between two arms of hairpin resonator). I have the length, width, quality factor and coupling co-efficient of the resonator.
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1answer
61 views
What is relation between power deposition and frequency?
1. What is relation between power deposition and frequency in electromagnetic waves?
2. Is it true that even very low power elec.mag.waves can be "dangerous" for long time health if ...
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1answer
42 views
I need help with hairpin filter design. Can anyone help me with the design steps and equations? [closed]
I have the coupled line design. But don't know how to convert it to a hairpin structure.
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1answer
44 views
Modelling a non-linear resistor on ADS
How can I model a non-linear resistor whose current changes according to the equation shown below on Advanced Design System (ADS) or AWR Microwave Office?
$$i(t)=v-v^2-v^3$$
Where v is voltage ...
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6answers
113 views
Why are transmitting antennas generally larger than receiving antennas?
The reasons I can think of are transmitting antenna has to be more directive also larger length will imply larger power and thus will help compensating for losses. But on contrary if receiving antenna ...
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1answer
24 views
How to calculate the properties of spiral antena?
I noticed some articles about analysis of Archimedean spiral antena. My understanding is that the antena of such type is a compact one and it allows broadband performance.
To be more precise I'd like ...
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1answer
27 views
Do surface charges exist when EM wave gets reflected by dielectric boundary?
If both the materials on a boundary are dielectric then do surface charge exists. I was solving using pillbox it showed that there should be surface charge on boundary to satisfy change in normal ...
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Split loop cavity or Loop gap cavity
I want to make a code for the power vs wavelength for the split loop cavity resonator. Can someone help me with the python code for the same?
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1answer
52 views
How can I match the FET's input and output impedance?
I'm designing a FET mixer, so I have to match the FET's input and output to in and out port's impedance(50 ohm). I don't have the S-parameters, but I can set wide range of parameters(GS-resistance, DS-...
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1answer
40 views
Which power combiner should I use?
I have two microwave signals (0.2 and 2.3 GHz) and I have to join these signals in a common channel (microstrip TXline).
I've decided to use two BP filters and a power combiner hybrid.
I've already ...
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21 views
How to implement this design in ADS(Advanced Design System)?
I was trying to implement this design in ADS. I have used coupled lines with all the dimensions but didn't get the expected result. Can anyone instruct any better way.
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33 views
EMI consideration for Microwave Sensor Module
I'm using Microwave Solutions MDU1720 datasheet with recommendation that The length of leads connecting the MDU to the signal processing circuitry must be minimised, to reduce pick up of ...
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0answers
25 views
How to provide gap between two separate structure or microstrip lines in ADS(Advanced design systems)?
I want to provide gap between two resonators. Here is an image. How do I provide those gap M12 and M23.
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0answers
34 views
Recommendation for RF simulation software that can do animations of wave motion through the model
I am trying to get an intuitive visual spacial understanding of the behaviour of RF electromagnetism though different shapes and materials.
Being able to visualise the wave motion is really helpful. I ...
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37 views
Losses over frequency for microstrip vs. coplanar waveguide
At mmwave frequencies, coplanar waveguide transmission lines generally have lower loss than microstrip. What accounts for this, besides radiated losses? Or is the difference mostly related to the ...
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1answer
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Impedance inverter transformation from series lumped resonators to lambda/2 resonators
Suppose I have the following series of filter transformations beginning with a lumped element bandpass filter and concluding with shunt susceptances-
The transformation from step (a) to step (b), and ...
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0answers
48 views
What does it mean to short circuit a transmission line stub at a specific frequency?
I'm currently designing a microwave FET mixer right now, and I have to short-circuit the FET's drain at LO frequency and its harmonics. I've checked the "stub" article in wiki, and it says ...
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1answer
98 views
Help choosing modern replacement for Hitachi 1SS86 Schottky diode
I’m trying to find a modern Schottky diode to use instead of the 1SS86 Schottky diode (Hitachi version, specifically). I want to use it along with a low current LED to build a lectenna that works for ...
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0answers
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ADS Interdigital stripline filter
I am designing a stripline filter with ADS and I am interested into the interdigital structure.
It seems that ADS only has SCLIN component for coupled edge structure, which is thought for parallel ...
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0answers
53 views
temperamental LED light
I have installed LED tubes in my kitchen ceiling light. They replaced the old fluorescent tubes. I removed the ballast and wired the fixtures according to instructions which essentially connected the ...
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3answers
85 views
Deriving the S-parameters, different Matched Loads possible?
I guess this is more of a conceptual question but for the problem below Im having trouble getting started on how to derive the S parameters for the network.
I noticed that the network at 28.025 GHz ...
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2answers
185 views
Simple high frequency (GHz) RF radiation detector
I want to build a simple RF radiation detector that shows if there are any RF devices transmitting at a certain frequency. I want to use it to detect RF radiation in the 2.4 and 5 GHz range. I have a ...
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1answer
29 views
2.45GHz microwave coupling to coil
I am currently developing a plasma-coating prototype.
As shown in the image, a microwave emits 2.45GHz radiation into an evacuated chamber.
A PET bottle is in chamber, filled with a low pressured gas.
...
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0answers
42 views
How i can automate a circuit using transistors instead switches?
I'm recycling the counter circuit of a microwave, for use it as a stopwatch, that turns on automatically, and start the count per seconds immediately when turns on, the circuit have two buttons "...
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1answer
56 views
What external influences can a cardiac pacemaker have?
Since in these days there are lots of different devices and appliances which are sending out all kinds of waves or radiation and different strengths (e.g. RFID scanners, induction cookers, Bluetooth, ...
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1answer
28 views
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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5answers
515 views
Can a lower voltage overheat a magnetron?
Background
I am working on a microwave oven that starts to emit an odor after 2 minutes of full heating despite otherwise working correctly. The smell is the same as that "sweet", ...
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2answers
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Switches and functions of microwave oven unresponsive on cold start
I have an old microwave oven which performs most of its functions, considering its age.
There is a slight problem that the switches go unresponsive and the LCD display fails to operate correctly if I ...
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2answers
156 views
Please help me solve the below Directional coupler problem
I have tried and my answer keep coming 0db.I am not sure this answer is right as this is only kind of problem I have seen where port is short circuited.
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0answers
23 views
Bias line using Microstrip
I need to bias a transistor amplifier operating between 12-15GHz. I will be using a microstrip bias line to connect DC to the collector as well as the base. I came up with the following simple design ...
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0answers
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Why does CST give “Error in field monitor calculation” after I change the frequency of the simulation?
I'm using Integral Equation Solver (IES) in CST (Computer Simulation Technology). I have one E and one H field monitor that are each 100cm^2. The simulation runs well at 100GHz, but when I up the ...
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1answer
46 views
Corelation between P0.1dB and IIP3
There is a corelation between IIP3 (third-order intercept point) and P1dB (1dB compression point) as shown below.
$$P1dB = IIP_3 - 9.6dB$$
Is there a corelation between P0.1dB (0.1dB compression point)...
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1answer
49 views
Do we need isolator after power amplifier in a microwave circuit?
I have been researching on the experimental setup for pulsed ESR. The setup consists of a microwave transmitter and a microwave receiver. I found that most setups use an isolator after the power ...
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2answers
76 views
How to measure microwave frequency with Lecher lines
I am working on a project where I need to measure the frequency of some microwaves (up to 10GHz) and as measurement tool I chose Lecher lines as they are easy and fast to build.
However after building ...
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1answer
39 views
Trigger motion sensor
I'm trying to trigger a motion sensor on a door (for fun and to learn more about these systems) using Arduino based electronics (ca 5V, ca 50mA). According to Wikipedia, these sensors (PIR sensors, ...
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0answers
41 views
Typical half-wave dipole antenna parameters
From my bachelors degree, I have learnt the fundamental theory behind antennas. One of the main types is the half-wave dipole antenna. We've studied its radiation pattern (isotropic) and how it varies ...
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1answer
70 views
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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1answer
41 views
Limits on frequency generation using nonlinear device + resonator cavity
I recently saw a schematic of an RF device which supposedly could generate a ~1GHz sine waveform via a 50MHz square wave run through a diode and fed into a cavity resonator.
What I'm curious about is ...
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0answers
59 views
Will a vacuum tank shield against microwaves?
I am working on an experiment that involves 50-250W of microwave radiation. The antenna will be inside a small vacuum chamber (~2ft Dia x 3ft long) with ~1.5" steel walls. There are a handful ...
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1answer
99 views
How is the antenna return loss measurement impacted by the cable's return loss?
Say you have an antenna (2.4 GHz) for which you want to know the return loss using a VNA. The connection between your VNA port 1 and the antenna is through a coax cable (e.g., Murata). The cable's own ...
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4answers
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How to Filter Harmonics in Wideband VCOs
I have a need for a RF signal generator, but I figured it would be a fun project to design a crude one myself. The main technical challenge I'm stuck on is how to filter out the harmonic content ...
