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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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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70 views

Why we need waveguide in Microwave?

why we need waveguide to move microwave power from magnetron to microwave cavity ? can't we just push magnetron antenna inside the cavity ? why it has to go through waveguide ?
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60 views

How do I control power of magnetron?

Magnetron as usually used in Microwave are fixed power setup, with power changes are done using suitably turning whole cycle on and off. Is there a way to control Magnetron power more linear way ? ...
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54 views

Klystron vs Magnetron for CVD

I am building Plasma CVD Reactor as a hobby project, and was wondering, which microwave source is better for Plasma Resonance Cavity ? I have cylinder cavity and would like to use power of around 1-2 ...
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29 views

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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22 views

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 ...
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30 views

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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13 views

Microwave frequency carriers and aperture error

In GPS and GNSS (global navigation satellite systems) engineering, one of the things we care very much about is the phase of the signal carrier. These are all microwave band signals. Typical sampling ...
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35 views

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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32 views

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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2answers
58 views

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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103 views

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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85 views

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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41 views

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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64 views

Measuring distances electronically? [closed]

Is there any way currently known that can accurately measure the distance between two objects. Say a phone and another device like a chip or another phone. basically measuring distances ...
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166 views

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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69 views

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 ...
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161 views

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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26 views

plane electromagnetic waves

In free space with no charge, both the curl and divergence of electric field is zero. Plane electromagnetic field exists in such region. Besides plane electromagnetic fields, does any other solution ...
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318 views

Microwave communication systems / data transfer rate vs data transfer speed

I'm researching about microwave communication systems, and I have to distinguish the difference between data transfer rate vs data transfer speed. I comment it will be something like you have a ...
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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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192 views

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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1answer
166 views

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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196 views

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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213 views

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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470 views

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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245 views

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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146 views

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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3answers
740 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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57 views

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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462 views

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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412 views

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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157 views

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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139 views

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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64 views

How to calculate probability of a cellular device being able to connect to a given cell site

How would one calculate the probability that a device would connect to a given cell site (assuming the device has more than one cell site in range)? I know there are a lot of factors, but what are ...
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239 views

Contact pad size for microprobe coaxial to planar waveguide transition

http://www.ggb.com/t-4.html Can someone explain what size one should choose at minimum/maximum for the pads and what role the pitch plays (besides impedance matching)? If I order a 100 micron tip ...
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1answer
2k views

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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582 views

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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619 views

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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10k views

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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1k views

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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450 views

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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1answer
57 views

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 ...