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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1answer
29 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'...
2
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1answer
43 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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0answers
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
33 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
559 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
93 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
104 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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0answers
98 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 ...
10
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1answer
788 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
77 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
29 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
43 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
84 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
38 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
41 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
48 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
96 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
63 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
86 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
22 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
185 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
108 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
93 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
309 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
56 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
58 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
57 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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0answers
35 views
Finding output SNR using Noise figure
am trying to solve this question below:
So I did find the system's overall noise figure to be 2.3 = 3.68dB, and you are more than welcome to verify it. However, my problem now is to find the output ...
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1answer
85 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
42 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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0answers
35 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
104 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
193 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
40 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
107 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
82 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
66 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
39 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 ...
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1answer
71 views
How are antenna arrays synchronized for direction finding/localisation?
How are antenna arrays synchronized for direction finding/localisation?
For example, if the processing unit is located closer to one antenna then another, it will see the signal from the closer ...
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0answers
117 views
Self Resonant Frequency VS Package Size for capacitor
In general belief, smaller capacitors have better charactristic(more capacitive behaviour) in high frequency than bulky capacitors.
On contrary in one of my RF project (8.5GHz - 9.5GHz) when checking ...
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1answer
563 views
Preamplifier for HB100 doppler sensor
I'am working with HB100 doppler sensor and I tried to build the amplifier shown in the datasheet of HB100. This amplifier uses opamp LM324, I don't know why it doesn't work. The Vout of the circuit is ...
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1answer
44 views
From how wide a range of angles can a grid of dipole antennas efficiently receive a power beam?
This paper on solar power satellite concepts makes brief reference to the ground receiver receiving an elliptical beam due to the angle it is at to the transmitter (2nd paragraph). The angle isn't ...
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1answer
138 views
Transmission line voltage measurement(visualizing standing wave)
I want to measure voltage across a T-line to visualize standing waves on the line.
something like this video min 6:53 and this experiment Measuring Standing Waves on a Microstrip Transmission Line
I ...
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0answers
31 views
Distance between via fences and the gap in CBCPW
What is the consideration involved in placing the via fences relative to the gap edge of CBCPW (Conductor Backed Coplanar Waveguide) ?
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0answers
34 views
Line/load matching for electric power transmission
Impedance matching is a critical topic for microwave engineering where the signal wavelength becomes comparable to the physical sizes of components. Substitution of distributed component models for ...
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1answer
69 views
Scattering matrix of matched a device with matched ports
The scattering matrix of a device with matched ports has zeros at the position of the corresponding diagonal element(I am referring to equation 7.2 or 7.4 in Microwave Engineering by David M Pozar, ...
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1answer
37 views
Are h- and g-parameters only applicable to two-port networks?
There are plenty of references to various ways to represent two-port networks (S, Z, Y, T, ABCD, h and g parameters).
S and T parameters are commonly generalised to N-port networks. Is the same true ...
