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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16 views
What exactly is source reflection coefficient and input reflection coefficient?
I just come across learning Microwave Amplifier. And I encounter two similiar coefficients: source reflection coefficient and input reflection coefficient. Illustration below from Microwave Engineer, ...
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2answers
100 views
Strange shapes on the Wi-Fi module PCB
LG has this Wi-Fi module:
This is a 2X2 Dual Band AC Wi-Fi / BT module. You will see two folded WiFi antennas on upper side and one bluetooth PCB trace antenna at the lower right side.
I found this ...
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1answer
33 views
relation between reflexion coefficient and power ratio
Assume you have an intermediate input/outpout device connected to a coaxial line.
For example, the device may be a DC-bloc, a bias tee, or simply a PCB microstrip transmission line.
Using a signal ...
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2answers
155 views
Microwave starts working when door opens - how dangerous is it?
I've just rented a house that came with an equipped kitchen, and I've found that the microwave has a rather weird behavior - opening the doors seems to trigger it to start working, which the owners ...
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1answer
59 views
Resonance in Yig oscillators - is it normal?
The advertised range of my recently bought YIG oscillator is 1.1 - 3.4 GHz.
On my spectrum analyser, I found 2 resonances, spaced at about 1 GHz and 2 GHz from the main peak (see picture below were ...
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0answers
21 views
RCWL-0516 Microwave Radar Sensor
I have recently been interacting with these cheap radar modules from China and works fine specifically the RCWL-0516 Microwave Radar Sensor. Now I wanted to integrate the entire circuit into a custom ...
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3answers
395 views
In microwave frequencies, do you use a circulator when you need a (near) perfect diode?
I am confused with the "diode concept" in microwave frequencies. As far as I could read, I found that even small signal Schottky diodes have a non negligible capacitance, that may perturb the signal ...
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0answers
29 views
Estimating the effect of dielectric bridges on a coplanar waveguide
I'll start with some context, but feel free to skip to the third paragraph for the concrete question.
In the context of superconducting microwave circuits (such as those used in some qubit ...
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1answer
82 views
rectenna, diode selection
Diode problem
Used 1N4148 in combination with 100 microfarad cap, circuit gave output 14.5V and 45uA on 200 Ohms load.
But, when I use 1N4007 or FR207, they do not work, nothing on multimeter.
Can ...
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0answers
46 views
Insights required to repair my Agilent YIG oscillator
I know, it's probably no chance. But let me try.
The model is HP-Agilent 0955-0520, Y088-4258, that can be bought for 600-900$.
Here is a picture.
When I bought the oscillator, I performed multiple ...
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1answer
39 views
Cutoff or Corner Frequency for Coax Cable
I'm trying to understand better what the significance of the cutoff frequency for coax cables is. I have a case where a cable is considered for use at frequencies up to 3% higher than the manufacturer'...
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1answer
45 views
What should be assumed regarding the upper frequency of sma connectors
There are infinitely many sellers of sma connectors of various kind in ebay or other stores. This one is an example.
But they very seldom specify what is the maximum frequency at which the device can ...
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8 views
The splittng node rule in Signal Flow Graphs?
When is the splitting node rule applicable? Is there any instance when it is not?
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1answer
38 views
How to convert from S-parameters to power gain?
With reference to the part below, which states 17dB gain at 500MHz for Vce = 12.5V
https://www.digikey.co.uk/product-detail/en/stmicroelectronics/PD55003TR-E/PD55003TR-E-ND/1664253
It's data sheet ...
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2answers
591 views
Difference between Antenna and Filter
In RF front-ends the diagram shows an antenna followed by a band-pass filter.
I am also working on a project involving a micro-strip patch antenna followed by a dual-band band-pass microwave filter.
...
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1answer
232 views
F-parameters instead of S-parameters
What are the F-parameters, how are they computed in CST and what is the relationship between S- and F-parameters?
In CST, they can be obtained, when running the integral solver and having a farfield-...
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4answers
115 views
Selecting coaxial cable and connector for PCB referring to required frequency
I want to transmit my 24GHz signal from PCB through coaxial to antenna. I wonder how to chose best match for it, also the power is -5dBm, 50 ohm. It's based on ADF5901 2ch PA. I have found two good ...
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100 views
How to line a Metal Melter secondary for higher safety
A Metal Melter is a kind of home-made low voltage (less than 40 volts, mine is 3v) welder (small-scale) made from a microwave oven transformer (MOT). I left the primary intact (the thicker wire, which ...
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1answer
839 views
90° Bend: Mitered vs Curved
On RF PCBs to bend a trace 90° you have many choices but among them Curved and Mitered bend considered as a good choice from performance POV (Both shown below).
For many years I thought that if you ...
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0answers
86 views
Can you generate a pure sine wave by mixing a fixed frequency sine wave with a variable frequency square wave?
Let us suppose I don't have a DDS available, and instead I have two square wave clocks with frequencies of my choosing. I have the impression that creating a wide bandwidth (multi-decade) sine wave ...
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0answers
32 views
HB100 microwave sensor impedence question
The patch antenna on these are minimal. I would like to cut the feed point and tap it with a short length of UT141(?) to feed two 10 GHz horns. Does anyone have a guess as to the feed point impedance? ...
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0answers
46 views
Determining required signal SNR (beat signal from FMCW RADAR)
I'm trying to determine the SNR required for signal outcoming from FMCW Radar.
This is the chain: signal will created by "24 GHz VCO and PGA with 2-Channel PA Output" by triangle shape frequency ...
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1answer
85 views
Microwave - Standard Intermediate Frequency?
VHF/UHF receivers use one of a few standard intermediate frequencies. Is there a similar set of standard intermediate frequencies for microwave (around 3GHz) receivers?
As I understand it, the choice ...
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1answer
69 views
Interpreting scattering parameters on a Smith chart.
I'm trying to become reacquainted with microwave circuits and how to analyze them, especially with a VNA. Just to get some practice I'm using Keysite ADS simulator.
To get the feel of it I used the ...
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1answer
44 views
Difference between a flared and not flared rectangular waveguide antenna
Someone can explain to me the difference in terms of performance between a flared rectangular waveguide antenna (precisely a pyramidal horn) and a not flared rectangular waveguide antenna?
In horn ...
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1answer
49 views
Free air or waveguide wavelength?
If you have a microwave frequency of say 2.45 GHz, would you use that frequency in a simple rectangle cross section waveguide, or do you need to use the "lamdba g" waveguide frequency I've read about ...
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1answer
119 views
Can a magnet cause a microwave oven to unsafely radiate energy?
I've already successfully warped the colors on a large old CRT Television by setting unshielded speakers on top of it. If I understand correctly, this was due to the deviation of the electro-magnetic (...
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1answer
64 views
Other than direct radiation, how can RF interference transfer between stacked PCBs?
I have VHF aviation radio consisting of 3 boards stacked upon each other: digital, receiver and transmitter, the digital is on ‘top’ with receiver in the middle, there is thick shielding between the ...
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1answer
124 views
Reference Plane In Impedance Calculation
I'm designing an 8-layer PCB with 10 distinct region of power. To attain 50Ohm trace I used Stripline calculators (like this fancy EEWeb) and they work great If you know that you have a complete solid ...
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0answers
25 views
CST Studio Space State Matrices
I am new to using CST Studio and I am trying to figure out how to see the state space matrices (A,B,C,D) of a designed antenna to describe its radiation pattern in other software. Any help on the ...
4
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1answer
280 views
Effect of VIA fence on grounded coplanar waveguie (GCPW)
I'm working on a RF Frequency board with up to 6GHz signals. To connect components on the board (Mixer, Attenuator, ...) I decided on using GCPW. I designed my GCPW Using AppCad calculator (free ...
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1answer
139 views
Impedance matching a capacitor load
I am currently trying to impedance match a capacitor as a load. In detail, it is an insulating thin film grown on top of a conductive layer (grounded). We now sputtered small Pt electrodes on top and ...
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0answers
114 views
Intuition behind transit angle of a klystron
What I understand is that the electrons get attracted to the anode and during their passage through the buncher gap, they regroup into bunches due to differing potentials imposed on different ...
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5answers
347 views
Why are cell towers so high? [closed]
Why do cell towers need so much height? Does the height increase antenna gain because it may provide directionality?
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1answer
61 views
Single tone signal generation at microwave frequency with best phase noise and spurious performance
What is the best way to generate a single tone signal with best phase noise and spurious performance?
Is frequency multiplication the best way? single stage multiplication or multi stage ...
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1answer
59 views
How cell sites work? [closed]
In Mobile communication, how do cell sites communicate to each other to the point when they reach the cell site which is connected to the other mobile phone when I make a call .
What is the medium of ...
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1answer
60 views
Metallic Waveguide Boundary
I've been studying TE and TM modes on waveguides for microwave frequencies.
It basically consists on applying Maxwell equations on a rectangular metallic cavity, with infinite length on \$z\$ ...
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1answer
100 views
How to build a simple waveguide and start on microwave electronics?
I have an electrical engineering qualification and new to microwave engineering, but really never did much RF or microwave when studying.
I want to build a very basic and simple waveguide microwave ...
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1answer
43 views
Ohmic power loss due to electric field
Recently I read in the basic EM theory course , that the Ohmic power dissipated in a conductor is directly proportional to the conductivity and the square of the electric field intensity , but we know ...
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1answer
51 views
Bounds of impedance matrix of a passive two port network
If we consider the impedance matrix of a linear, reciprocal passive network (Z12 =Z21 because of the reciprocity),
$$
\begin{bmatrix}
Z_{11} &
Z_{12} \\
Z_{12} &
Z_{22}
\...
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1answer
125 views
Why no IEEE 802.11 version use 24 GHz ISM band?
IEEE 802.11 aka WiFi uses multiple ISM bands to transmit data,2.4,5 and 60 Ghz.The 24 GHz was never used in WiFi,why? Why did they jump from 5 to 60 and ignored 24? Why no wireless standard use this ...
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1answer
230 views
High current low voltage transformer not working
I have rewound a microwave oven transformer to produce a low voltage on the secondary. I'm not sure what the ampere rating of the transformer is but its about 4mm thick wire on the primary.
I wound ...
2
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1answer
26 views
Co-application of DC field and Microwave Irradiation on Soil
I am attempting to design/enhance a system which applies direct current to a soil for the electro-kinetic remediation of organic/metal contamination. My current plan is to try enhancing conventional ...
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0answers
41 views
RF signal on wirebonds
I am curious to know how RF signal is transmitted through wirebonds. I thought that in microwave transmission lines, the energy was stored in electric and magnetic fields inside the dielectric ...
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2answers
2k views
What causes loss of power over lifetime of a magnetron?
The power of a magnetron declines over time\$^1\$. While not noticable for most consumer applications (A 2000-hour lifetime would last over 20 years if the device is used only 15 minutes a day), this ...
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0answers
67 views
Can I trust these microwave power readings?
So I've got an old Hughes TWT that supplies roughly 20W across the Ku band (12.4 - 18 GHz) that has a waveguide output flange (WR-62). I am "gently re-purposing" it to be driven at a lower frequency (...
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1answer
120 views
Microwave oven with no heat, Bad design or wrong component choice? [closed]
Few days ago, my Magic Chef MCD990B microwave oven magically passed away randomly and so suddenly that I didn't even have time to say goodbye, not that I have used it heavily or considered it as my ...
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2answers
89 views
Multiband LNA Design [closed]
I am familiar with circuit design - Basic Op-Amp Design, concepts like stablity, Phase margin and I am a beginner in Microwave Engineering. I am familiar with some basic ideas and little familiar with ...
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1answer
86 views
Rectangular Waveguide H-Plane Step Discontinuity - Equivalent Reactance for Change in Height
I have been reading Pozar's Microwave Engineering, and in Section 4.6, he goes through the analysis to determine the reactance of a discontinuity between two coupled waveguides. In that chapter, he ...
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1answer
44 views
AWR PA Output Power Simulation - Credible?
I'm working with the SKY65111-348LF power amplifier from Skyworks and wanted to obtain some idea of its performance using AWR Microwave Office. I'm not sure if my process is correct and wanted to have ...
