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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Characteristic impedance: TDR (function of position) versus VNA (function of frequency)
A TDR gives you the characteristic impedance of a transmission line as a function of position. You can also measure the characteristic impedance of a uniform transmission line using a VNA, which gives ...
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Using 2.4 GHz microwaves to demonstrate optical polarization
Several educational companies sell kits to demonstrate optical polarization using 3 cm (10 GHz) microwaves emitted from a Gunn diode transmitter and simple grid-like polarizers.
My question is whether ...
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Could a DIY 1 kW portable version of the military non-lethal microwave beam active denial system (ADS) be made?
How would one create a portable 1 kW microwave emitter that projects out a 95 GHz beam to about 5 - 10 feet? What kind of components would be required?
I recently came across this fascinating video ...
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How to generate microwave band frequencies like 85GHz? Is there a DIY device or parts kit to do this? [closed]
Let's say I want to build a device that generates and sends out a microwave of some arbitrary specific frequency to a short distance, say 1 - 2 feet.
For example, 95 GHz.
Is there a straightforward ...
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Help in understanding resonance in 1/4 wavelength detector / S parameters
So this might be long question that requires some literature review but I will try condense it as much as possible such that hopefully I can get some help without the reader having to review the ...
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Is my VNA broken or miscalibrated, or are these weird results normal?
My company got a new vector network analyzer recently and I'm using it to try to learn more about microwave circuits, especially the resonant cavities that we use in our measurement systems. I've seen ...
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What does the value of R_t represent in Balanis' bowtie antenna design equations?
I'm using Antenna Theory: Analysis and Design by Constantine Balanis to aid in the design of a wideband antenna. I believe a bowtie antenna will satisfy my necessary bandwidth, however Balanis notes ...
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HB100 Doppler sensor calculation
I have a question about the first circuit schematics.
I calculated the second circuit's fcutLow and fcutHigh frequencies like this:
f2CutHigh = 1/(2 * π * 1M * 100p) = 1.6 kHz
f2CutLow = 1/(2 * π * ...
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DIY spot welder from microwave transformer (nicked primary coil)
I am building a spot welder in order to combine 18650 battery cells into battery packs using nickel strips. I have viewed several online tutorials that describe the process of creating this tool using ...
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Effects of ferrite isolator on waveform
I have recently measured the standing wave signal from a waveguide. I notice that as the frequency is lowered the signal tends towards a sawtooth wave.
**
My guess for why this happens is that the EM ...
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Error during analysis in AWR Microwave Office
How to fix this error, and what does it mean?
A port is off grid. All polygon edges with ports attached must be 'snapped' to the grid.
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What dictates the current drawn by a magnetron's anode?
Typically AFAIK in a magnetron from a commercial microwave oven, the cathode filament is heated by a 3.3V 10A supply, generating a cloud of electrons by thermionic emission. The anode cavity resonator ...
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RF preamp, or no RF preamp?
Frequency downconverters are required to test devices that operate in the range of microwave and mmwave. I have noticed that some companies use a signal chain that has an RF preamp, and some do not, ...
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Hspice mode of a Lossy Transmission line
Can someone provide a HSPICE model of a lossy Transmission line which I can simulate in Cadence virtuoso or Synopsys custom compiler?
I need lossy Transmission line model for Z0=50ohm and length =...
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Radio frequencies, what are the limits?
What is the correct range of frequencies for radio waves? Wikipedia's article on radio waves states that all frequencies below 300 GHz are radio waves, while the article on the radio spectrum states ...
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Is a microwave's cooking cavity of particular dimensions according to the characteristics of the input microwave feed?
i.e. if I were to connect the magnetron inside my microwave to a slightly different steel box (see pic) of a different size and shape (provided the volume inside was roughly similar to the one in my ...
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Microwave injection into cavity, approximately 2.4GHz
I need to inject a few Watts of microwave radiation transversely into a pipe. Since I have no microwave expertise I would like some general advice.
My naïve expectation is to somehow couple the ...
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RF amplifier with square wave response
I want to amplify a 600MHz, 100pS rise time LVDS signal. This signal will be a pulse and I want to amplify each pair separately. If I use an RF amplifier like MMG3H21, I guess it will add oscillations ...
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Intuition for S-parameter formulas?
Wikipedia defines S-parameters as[1]:
$$
\boldsymbol{b} = \boldsymbol{Sa}
$$
Where:
$$
a_i = \frac{1}{2}k_i (V_i + Z_i I_i)
$$
$$
b_i = \frac{1}{2}k_i (V_i - Z_i^* I_i)
$$
Saying it is defined in [2], ...
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Rollett stability factor - derivation and numerical meaning
For two-port networks, a value called the Rollett stability factor, K, can be derived, whose value can then be used to assess one of the criteria for the network to be unconditionally stable (K > 1)...
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PLL design in amplifier
We have designed a PLL for an operating range of 11-14 GHz. The output of the VCO goes directly to the amplifier, and then to a divider, see the picture.
Is there anything that affects PLL locking ...
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Microwave receiver antenna height
I want to do a simulation of fixed-service microwave links and I want to know how antenna heights above ground level (AGL) are determined on the receiving side.
For instance, if the transmitter ...
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Impedance matching
I am a newbie at microwave. I'm confused about impedance matching. So far just 50 Ω impedance stub in outside.
But in this example below I saw 75 Ω. I could use the Smith Chart but I didn't know how ...
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How is the frequency in the label behind microwave ovens determined? How could one measure the frequency?
It is very common online for people on youtube, forums, and other social media to bring up the following fun home experiment to "measure the speed of light" using chocolate and a microwave ...
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Connecting 2 microwave transformers in cascade to get 22kV?
I'm an electrical engineering student, and I am working currently on a project using a microwave transformer, and creating something like Jacob's ladders.
If I take two microwave transformers and ...
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What is the rated output current in different MOTs?
I've been looking at LG service manuals, searching parts numbers, and the lot; but I can't seem to find anything concrete. I see websites throwing around "generally 1 amp" a lot and other ...
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How to avoid impedance discontinuity when a pcb trace is routed in multiple layers
What are the things to be take care to avoid reflections when a PCB trace is routed in multiple layers. I mean, How to achieve impedance control when trace moves from one layer to other.
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Binomial matching (RF & microwave)
In a Binomial Matching Transformer, we're expecting the reflection coefficient to be the following function:
\$\Gamma(\theta)=A(1+e^{-2j\theta})^N\$
What is the philosophy behind assuming this ...
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High-speed PCB crosstalk, inductive vs capacitive
I know that at the time of crosstalk Capacitive as well as inductive currents generate voltage drops on the victim line over termination resistors.
I have three questions.
1)Why inductive crosstalk ...
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Dual-band planar power dividers with center frequency ratio 3
I am trying to recreate the results of the paper published in IEEE Transactions on Microwave Theory and Techniques.
In that paper, it is said that for a pure resistor the frequency ratio is 3 i.e. \$...
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Reconciling phase shift error of length-tuned structures in 81-86GHz I/Q direct down-converter ASIC with datasheet specifications
I'm watching a video on reverse engineering a GaAs 81-86GHz I/Q down-converter ASIC. The relevant section of the video for this question is 10 minutes onwards, but watching the video isn't necessary ...
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How is the height of the steps in the stepped transition of the waveguide determined?
I am reading in the book "Microwave filters, impedance-matching networks, and coupling structures" by Matthei, Young & Jones about step transformers in waveguides. An example of the ...
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Is there any way to change linearly polarized emag wave polarization as it is propagating without altering propagation direction or Az/El patterns?
Let's say I have a vertically polarized emag wave, but I want to convert it to horizontal after it has already been emitted from the source antenna without altering its propagation direction or Az/El ...
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How ground plane acts as a low impedance path and shielding action of ground plane
I am new to high speed design .Please don't flame me if this question is very basic :)
Below statement is from AD application note. (AD Appnote)
"The ground plane not only acts as a low impedance ...
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Coupled line hybrid coupler parameters
I am designing a coupled line hybrid coupler as a part of of term evaluation at my university. So from my conceptual understanding here coupled line hybrid coupler implies a coupled line coupler with ...
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S21 & S12 of a mismatched transmission line
I am trying to solve this problem:
Since it is asking for a reference impedance of 50 Ω there will be a mismatch, and hence reflections at the Port 1 for calculation of S12.
I already know S11 and ...
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Microwave oven approximate efficiency [duplicate]
I just made popcorn in the microwave and I wonder how much energy my popcorn absorbed and how much energy was consumed by oven. It was 90g of corn and butter (kind of...) and it needed 800W for 3 ...
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How is the center pin supported in air-filled coaxial cables?
In SMA cables, the PTFE dielectric supports the center pin through the length of cable.
How is the center pin supported in air-filled cables? E.g., 3.5mm, 2.9mm, K-connector, 1.8mm, V-connector, etc. ...
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How to include magnetic loss in transmission line equations for coaxial cable?
I'm trying to calculate the attenuation per unit length (\$\alpha\$) of a coaxial cable, including dielectric dissipation (\$\varepsilon^{\prime\prime}\$), magnetic dissipation (\$\mu^{\prime\prime}\$)...
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Why are the noise input and noise output the same in a two-port network consisting of a passive, lossy component?
I am reading Microwave Engineering from Pozar, chapter Noise and Nonlinear Distortion.
It says in the book:
Because the entire system is in thermal equilibrium at the temperature T, and has a driving ...
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Why do we need a resistance match at the output for measuring noise?
I am reading the book Microwave Engineering from Pozar, Chapter Noise and Nonlinear Distortion.
As I understand it, impedance matching is designing source and load impedances to minimize signal ...
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What is bandwidth of a resistor
I am reading the book "Microwave Engineering" from Pozar Chapter Noise and Nonlinear Distortion.
Pn noise power from the circuit can be described as the following formula. Pn depends on B, ...
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How or why are powerful but low-frequency radio waves, such as from a radio station or cell tower, potentially dangerous? [closed]
Cell towers / base stations and such are limited in the power they are allowed use, even if the wavelengths of radiation used do not adversely affect people or animals.
I have heard (and read) that it ...
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Bandpass filters using capacitively coupled series resonators
I was wondering how to decide on the gap size for capacitances. Here is the figure from Microwave Engineering by Pozar:
I can calculate the B values, θs and other related stuff. Furthermore, I can ...
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Tesla valve/ valvular conduit
What happens if a radio or any electromagnetic wave passes through Tesla valve/valvular conduit? How will the valve behave to an EM wave? What will be the output?
Will the EM wave behave exactly as ...
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Basic question about radar
I am learning about automotive radars and have a very basic question about them.
If two or more cars on a road have the same radar, using the same radar tech (e.g. CWFM radar) how will one car's radar ...
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Dual directional coupler schematic?
I am new to microwaves. I am trying to design a dual directional coupler using ADS software, but researching dual directional coupler isn't working; all that's showing is directional couplers and bi-...
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Can a weak external magnetic field damage a magnetron?
I have a 40-year old microwave oven. I temporarily attached a magnetic flashlight to the side of it. Its 5/8"-diameter magnet is likely a neodymium magnet, strong enough to secure the 10-ounce ...
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Is it possible to make a microwave frequency oscillator with an LC circuit? [closed]
Can a Colpitts oscillator circuit consisting of pF value capacitors and nF value SMD inductors be used as a microwave frequency (within 500MHz, 5GHz) oscillator.
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How is the PASCO microwave receiver realized?
I took a physical lab course where I worked on the microwave PASCO set-up WA-9316.
Having a little background on electronics, I wondered how their microwave receiver works and found a more or less ...
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