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 to make an impedance matched circuit for fabbed antenna?

Okay I have developed an antenna for a system and need to create an impedance matching circuit. The theory of conjugate matching is simple, but actually implementing it is something I can't find ...
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2answers
250 views

Pinout of microwave motion sensor FC1816

Please, help to figure out the pinout of microwave motion sensor FC1816. The seller "doesn't understand" what it is required on queries to provide the pinout for the module. The module is the ...
4
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1answer
77 views

Phase noise measurement with IQ mixer

I have a question regarding a measurement scheme of phase noise that I'm trying to implement. The idea is that I have two identical signal generators (I actually do) that generate a sinusoidal voltage ...
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1answer
95 views

Distributed Transmission Line, Characteristic Impedance in AWR Microwave Office

I am trying to design a distributed amplifier in which the parasitic capacitances of a small-signal FET model are linked to inductors to form a distributed line across the drains and gates and I'm ...
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6answers
2k views

Is a microwave's output power proportional to the mass of its contents?

My friend and I are having a heated debate. On the one hand, he thinks that a microwave oven that is empty, consumes almost no power (not considering lights, lcd, etc). He says that once you put an ...
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0answers
119 views

GaN pulsed operation

Does anybody have experience biasing and pulsing a microwave GaN HEMT? I've just ordered a 10 Watt S-band transistor. I know all about bias sequencing. This application is pulsed. I've read about ...
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2answers
131 views

Smith Chart Conjugate Matching

In an example in Pozar's Microwave Engineering, a conjugate matching circuit for maximum gain is designed using Smith chart. In the shown Smith chart, the matching circuit for input is designed. We ...
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1answer
36 views

Is it possible to model a microwave resonator in SPICE [duplicate]

I just wanted to know if it was possible to model a microwave resonator in spice software or somehow import it from somewhere to spice to carry out analysis. Also if it is not possible to model the ...
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1answer
164 views

Coupled Line Filter Design in Qucs

I'm getting to grips with designing coupled line filters and wanted to implement the band-pass filter described in Example 8.7, p. 435 in David Pozar's excellent "Microwave Engineering" just as a ...
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1answer
67 views

Output reflection coefficient of a two port network

In the third edition of the textbook Microwave Engineering by David Pozar, example 4.7, it is explained how to use signal flow graphs to find the output reflection coefficient \$\Gamma_{out}\$ of a ...
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1answer
58 views

LED characteristics to use in heating a material sample?

I am looking to be able to heat a sample of material, typically less than 500mg and sitting in a fused silica sample holder about 10mm diameter. Wondering about using (say) a 5W LED with narrow ...
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1answer
64 views

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 ...
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2answers
164 views

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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2answers
148 views

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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2answers
83 views

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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1answer
156 views

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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1answer
65 views

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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1answer
48 views

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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1answer
121 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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2answers
151 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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1answer
38 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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1answer
40 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* ...
2
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1answer
51 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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1answer
61 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
180 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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1answer
152 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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1answer
147 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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1answer
105 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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1answer
412 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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1answer
190 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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3answers
305 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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5answers
5k views

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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2answers
364 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 ...
3
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1answer
273 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 ...
5
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2answers
681 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 ...
5
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2answers
867 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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2answers
675 views

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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1answer
978 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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0answers
66 views

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 ...
2
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1answer
364 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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1answer
251 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 ...
2
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3answers
2k 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 ...
0
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1answer
87 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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1answer
713 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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2answers
663 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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2answers
237 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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1answer
168 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. ...
4
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1answer
290 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 ...
2
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1answer
4k 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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1answer
737 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 ...