Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [high-frequency]

This tag marks questions related high frequency (radio) circuits.

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490 questions
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13 answers

Why do fundamental circuit laws break down at high frequency AC?

We're just starting the whole RF scene having dealt with DC and low frequency AC for all our previous courses. I understand that at high frequency AC, fundamental circuit laws don't apply anymore and the classic passive component models need to be…
AlfroJang80
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Why is 50 Ω often chosen as the input impedance of antennas, whereas the free space impedance is 377 Ω?

In order to efficiently deliver power to a different part of a circuit without reflection, the impedances of all circuit elements need to be matched. Free space can be regarded as a further element, since a transmitting antenna eventually should…
DK2AX
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Am I insane to question that only with a closed path can electrons move?

First of all let me just state that I do not feel confident enough to tell anyone anything about how electric circuits work or anything about the physics behind them because I simply do not know or understand it all. But I have many times read that…
µDavid
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Can anyone explain this high-frequency "alien voodoo black magic"?

I was casually watching Mike tear down a spectrum analyser (13:30 is the relevant part, 16:50 is the awesome part), and he came across what he aptly described as "weird messed up alien voodoo black magic stuff": As a layman, I can only nod in…
Polynomial
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At what frequencies does PCB design get tricky?

I have designed many mixed-signal PCB's where the highest-frequency component is the microcontroller's crystal oscillator itself. I understand the standard best practices: short traces, ground planes, decoupling caps, guard rings, shielding traces,…
bitsmack
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Why solder mask are not applied to RF PCBs

I've gone through some of the RF PCB designs. In which solder masking on the traces are not present. Like this one Is there a specific reason or performance issue to remove that?
Abhishek Parikh
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Why does an inductor behave as a capacitor at high frequencies?

In truth, I've only been told this anecdotally by an instructor, but can someone explain the physics at play? I have been told that if an inductor is driven at a high enough frequency, it will begin to behave as an capacitor, but I cannot figure out…
Michael
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Is this a good design & layout of an active differential 'scope probe?

This question is an extension of Homebrew differential 'scope probe. I thought I should make this a new question though. I need to measure a 100Mb/s LVDS signal to check its integrity. I will try to get hold of a 'scope with a 600MHz bandwidth, but…
Rocketmagnet
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When laying out circuit board traces, what impedances do I need to consider?

I do low-speed circuit design for microcontrollers and such (usually at less than 20 MHz), and now I'm getting started on some more high-speed circuits. What I want to know is: What considerations need to be made for traces in high-speed…
machinaut
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Is this true: "At over 700 Hz, current simply flows over your body"?

I have heard this in a movie clip. I was just curious to know, is this really true? Because the one thing that I do know, is that at a high voltage, the current decreases, so that it doesn't harm a human body.
Pawan kumar
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Why do microwave ovens use magnetrons?

With a lot of advancement in solid state electronics and signal manipulation, isn't it easier to simply take high amplitude signals with frequencies near 1 MHz and multiply the signals using diodes and frequency filters(LC/RLC) than to use a…
Vishwa Mithra Tatta
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Why isn't there a non-conducting core wire for high-frequency coil applications

Background The commonly known skin effect formulas are derived and only apply to solid conductors. The commonly used "skin depth" only applies in these cases. It is for this reason that in some applications tubes are used, as these are much more…
Edgar Brown
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Crazy homebrew 500 MHz 1 Gs/s oscilloscope possible?

I was reading USB scope probe - request for comments and ideas, and it got me thinking. What I'd really like is a very high performance oscilloscope, one which would cost $10000 or so. Surely many other people would like one too. And surely, with…
Rocketmagnet
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Need an XOR gate that works up to 2 to 3 GHz

I have encountered an unusual situation in which I require an XOR gate that will function reliably when presented with a square wave input with a frequency between 2 and 3 GHz. I know that desktop CPUs have logic gates that can function at these…
okw
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What to think about when designing HF PCB's?

I am currently designing a small PCB in Eagle Cad that has a GPS 1PPS signal (one short pulse per second) as input. The pulsetime for the 1pss is something like 1us. Ok, I know thats not super HF but still. What are good design practises when…
Theodor
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