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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Function to Simulate Realistic Waveform
I need to simulate a realistic signal voltage triangle waveform in Mathematica. I know that a real waveform won't have sharp corners, but I don't remember exactly what a real triangle wave looks like....
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Why is a high-Q circuit difficult to match?
People in the microwave/RF field constantly talk about how it is "difficult" to match a high-Q circuit (ie. a CS amp with very little gate resistance and no degeneration). Why is that?
The problem is ...
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Why does microwave communicaion require line of sight?
What I can I think about is:
Power spectrum density at MW frequencies is very poor at a point it is unable to penetrate obstacle without losing a lot of power.
Multipath fading at those frequencies ...
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Signal speed through different materials
I've been tolled that signals are carried by electromagnetic waves caused by oscillating charges, and that this action occurs in a manner similar to how billiard balls interact with one another.
I'm ...
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HEMT/PHEMT transistor circuit design- need manual/book
I have to design a microwave amplifier in the frequency range of 0-15GHz. To this end, I need to be able to design circuits with HEMT/PHEMT transistors. Is there a comprehensible manual that teaches ...
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Microwave amplifier characteristics - don't undertand [closed]
Please, look at http://www.rfcomp.com/hd24223.aspx (the spec file is downloadable in this page). This is a microwave amplifier, and I have several questions.
1) What is "noise figure" ?
2) What ...
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Electromagnetic or microwave cooling
Heat means stored kinetic energy in matter. Microwave owens and induction heaters works on increasing kinetic energy on matter. Is it possible to make inverse of this heaters like cooler. We can ...
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Why do we need a waveguide in a microwave oven?
Why do we need a waveguide to move microwave power from the magnetron to the microwave cavity?
Can't we just push magnetron antenna into the cavity?
Why does it have to go through a waveguide?
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Relation between reflection (coefficient) and bandwidth
I am reading into single stage microwave amplifiers and how to design for a specific gain (source 1, source 2 warning PDFs!). In both sources the claim is made that the highest bandwidth is achieved ...
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Explanation for stability criterium microwave amplifiers
Given a general microwave amplifier circuit
For this amplifier (transistor) to be stable the the magnitude of the input and output reflection coefficient must be smaller than 1.
But why? What is an ...
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EM wave polarization check
I am trying to recall the quick way to check the EM polarization theoretically, I mean if I have a wave described as (ssume capital letters are vectorial fields)
\begin{equation}
\ E = E_o *exp(j* \...
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Microwave oscillator conditions
The conditions for a negative resistance microwave oscillator are (2-port):
\$K < 1\$ (unstable device)
\$Γ_{in} \cdot Γ_g = 1\$ (condition for oscillating input port)(generator side)
\$Γ_{out} \...
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Microstrip lenght problem
I'm simulating a single microstrip half-wave resonator (1.8 GHz) in Sonnet and using ADS LineCalc tool for calculating the microstrip length but I'm getting a wrong number.
Substrate parameters (...
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Uneven (10 dB) RF Power Splitter/Combiner
I'm trying to modifying and improve the MIT radar project
Here's the basic block diagram:
Input power is split by 3 dB SPLTR1 to transmitting antenna and LO input to the mixer. From what I ...
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40 GHz spectrum analyzer with N-type coax input?
We have an old Rohde & Schwarz FSEK 30 that is advertised as having a range from 20 Hz to 40 GHz, with an N-type input connector. My conundrum is that a type-N connector with air dielectric ...
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How does a microwave oven-leakage detector work?
What type of sensor or circuitry is inside one of these devices that allows measurement of microwave radiation strength? I've never opened one but I'm assuming it's similar to measuring RSSI on a ...
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Isolation spacing in CPW-G
Is there any thumb of rules how to determine optimum spacing (marked with S below) for a RF signal (@2.45 GHz) on Coplanar Waveguide with ground (CPW-G)?
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Workings of a microwave oven magnetron transformer
I took apart an old microwave oven just to see what happens with the circuit inside it. The overall idea is actually pretty simple, but I'm having a hard time figuring out some parts of the circuit. ...
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How to determine dielectric constant and loss tanget of a PCB board at a specific frequency?
I need to know dielectric constant (relative permittivity) and Tan loss of a FR4 board at 2.45 GHz.
The specification of the manufacturer is as it is below:
Dielectric Constant:
Test method (IPC-TM-...
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How much power can a thin wire handle before heating too much?
If I have a copper wire 25um in diameter and 3mm long, and I'm running AC current through it at 3GHz, how can I calculate how much it heats up given a power and duration? The wire is immersed in oil ...
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Why do microwave ovens, with metal walls, not blow up?
Why does a microwave oven with metal (?) walls work fine, but if I (theoretically) put a metal spoon in it, "bad things" may happen?
Maybe these internal walls are not conductive?
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What is actually transformed in quarter wave transformer?
I'm reviewing some stuff on quarter wave transformer for a transmission line but since I have not had any experienced in handling these type of stuff, I am struggling to understand this concept ...
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Estimating Path Loss from Measured 2.4Ghz/Wlan Signal Strength to get Distance
I want to estimate distances between Wlan Routers based on the RSS (received signal strength) indoors. Im fully aware that I only will get rough estimates. For that I studied some radio propagation ...
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What are the bare minimum parts needed to operate a magnetron?
I recently took apart a microwave, and I managed to get a magnetron out of it, as well as a transformer that appears to be the power source for the magnetron, but looks a little small for the ...
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How Reflex Klystron works
I have a doubt on how exactly a reflex klystron works(as an RF source). In wikipedia it says that,
The electrons are fired into one end of the tube by an electron gun. After passing through the ...
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Wavelengths blocked by a certain metal mesh
Introduction: I've heard about a theory, according to which you can check if there is any leakage in your microwave oven by putting your mobile phone inside and call it. However, I gave it a try and ...
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Why does the speed of the Electromagnetic wave in the material depend on the frequency of the wave where as they are constant in vacuum (freespace)?
I am confused on why would the propagation speed of any EM waves at ANY frequency is constant in the free space (vacuum) but they seem to disperse in any other materials as the propagation speed of EM ...
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Microwave Oscillator: Both Ports Unstable?
I'm just wondering, for microwave oscillators, I think both ports need to be in the transistor's unstable region. What would happen if just one port were in the unstable region and the other in the ...
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What does this capacitor do? (Microwave biasing circuit)
I'm wondering what \$C_B\$ attached to the bottom of \$R_{C2}\$ does. This is a screenshot from a textbook called RF Circuit Design: Theory and Applications by R. Ludwig And P. Bretchko. Looking at ...
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How to calculate Input backoff per carrier of a satellite
I was trying to calculate the sizing of SSPA in my satcom network where input backoff per carrier is required to calculate Power flux density.
My current network configuration in C band is
Total ...
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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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RF Ground (Reflections?)
I'm trying to understand how someone can ground an RF signal (especially relating to microstrip lines). I think I'm missing something... Since the impedance of ground is supposed to be \$0\Omega\$, ...
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How to model transistor ATF 53189 in QUCS?
In my internship I have to create an amplifier with low noise, high impedance and that works in the 100 to 400MHz band.
While searching for a transistor, I found the ATF 53189 (datasheet), which ...
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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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Industry standard measure for coaxial cable stiffness?
Is there an industry standard measure for coaxial cable stiffness? By stiffness I mean the spring force experienced when bending or deforming the cable.
In my search for a highly flexible lab test ...
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DIY Ultra High Frequency
The book Crystal Sets to Sideband has discouraged frequencies above the low VHF band due to all of the problems with wires acting as inductors and difficulty on a stable Variable frequency Oscillator.
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Contact pad size for microprobe coaxial to planar waveguide transition
http://www.ggb.com/t-4.html
What size should one choose at minimum/maximum for the pads and what role the pitch plays (besides impedance matching)? If I order a 100 micron tip diameter Ground Signal ...
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How do IMPATT and TRAPATT diodes work?
I was reading some text on microwave devices when i came across these devices.The explanation in the book was very convoluted and difficult to understand. Could some one please explain to me
Basic ...
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Building a cheap and stable microwave network analyser or oscillator (2-5GHz)
I am interested in measuring the changing dielectric constant of a liquid as it undergoes a process. My background research of scientific articles shows that the 2-5GHz range provides the best ...
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Differences between a planar coil and coplanar waveguide to create a local 1D AC magnetic field
Coplanar waveguides (for example picture look here) are often used in research to create a local in-plane magnetic field. Now if compared to a planar microcoil like this,
driven by a AC voltage in ...
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Connecting horn antenna to a gunn transceiver
I have a surplus Microsemi MO9072 24GHz gunn transceiver (Datasheet) and a matching MDT86552 horn antenna (Datasheet) that I'd like to use in a project. In the same package was a waveguide of some ...
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How to terminate a coplanar waveguide with 50 ohm load?
So I want to structure a coplanar waveguide by lithography, VNA - coaxial - picoprobe - coplanar waveguide transition to measure impedance of the waveguide. As signal and ground lines are on one ...
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24GHz Radar : IF amplification and strange mixer output
I am currently working on a project where I have to study a microwave Doppler Radar.
Here are some details so that you can better understand it : a local oscillator (LO) at 24GHz is linked to an ...
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GPS error reasons and maximising errors
I noticed that when using gps in mobile phone, I am positioned away from a wall if I stay very close to it. For example on a street with buildings on both sides, I usually get my location fix on the ...
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Can I improve the directivity of an X-band radar module with integrated plane-patch antenna?
Lots of detail provided in case it's needed.
I'm continuing to tinker with remote proximity sensors driven by an Arduino (and eventually just an ATMEGA* chip and its safety buddies) and have a pretty ...
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