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1 vote

Impact of circuit length in high frequency circuit

The formula you used is for the ohmic resistance. Typically, ohmic resistance is much lower than the characteristic impedance. And for long coax cables, where it would seem important, the losses due ...
2 votes
Accepted

Impact of circuit length in high frequency circuit

I don't understand why the length doesn't matter though the equation is: R = ρ × length / surface. Ask yourself this very important question: when you activate a light switch on your wall (and ...
  • 396k
1 vote

Impact of circuit length in high frequency circuit

You are confusing resistance to the characteristic impedance. A coaxial cable, or any other transmission line, ideally has zero resistance so there is no losses, but for a wave or impulse travelling ...
  • 96.6k
4 votes

Does the L/C-shunt vs C-shunt/L order of an L-match matter?

\$\color{red}{\text{There was a(n unintended) mistake, please see the edit!}}\$ Feel free to downvote. In the first picture you're not showing the input impedance but, if it is accounted for then the ...
5 votes
Accepted

Does the L/C-shunt vs C-shunt/L order of an L-match matter?

At one fixed frequency, either topology can be used, and it doesn't really matter which. However, you may want your network to provide matching over a range of frequencies. If that is the case, then ...
2 votes

Does the L/C-shunt vs C-shunt/L order of an L-match matter?

In Schematic 1, L1 and Z1 can be interchanged. In Schematic 2, L and C cannot be interchanged. The labeling in Schematic 2 is incorrect. See below: simulate this circuit – Schematic created ...
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2 votes
Accepted

Send a video radio signal via a PC to a portable VHF/UHF TV

A solution using suggestions e.g. 'a D/A converter' in your question requires very in-depth knowledge of electronics, RF design and signal processing. It would be a very complicated thing to do even ...
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1 vote
Accepted

Step by step calculation of noise factor does not match the overall system calculation

I found another question that is in essence identical to this one but described in general terms. The answer provided by @joribama answers my above question as well. In my question above, the noise ...
4 votes
Accepted

How is the center pin supported in air-filled coaxial cables?

They use some type of spacer, the exact type depends on manufacturer. One common type is a helical spacer of a dielectric material such as polyethylene. Other types are similar, some form of plastic ...
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0 votes
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Bad GSM network automated testing

Consider altering the environment instead of the equipment: How about get any kind of linear actuator and slide metal plate over the device: Or a hinged metal box, open and close with a servo:
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0 votes

Alternative wireless technology for passive RFID tags

I've tried to optimize the readbility of UHF RFID tags in a library application, and one suggestion I can give is the use of multiple stickers per item. For something like a phone, place the sticker ...
4 votes
Accepted

Why is On Die Termination (ODT) only available for Data Lines (DQ, DQS) but not for Address Lines in in DDR2/DDR3 memory?

Because the address and control lines need to be connected to ALL of the chips on a memory channel, vs. the data lines are only connected to ONE chip (in each rank, and only one rank is active at any ...
1 vote

Generating DC signal using a phase detector

If you use a longer wire for a signal, you get a delay, the signal needs more time to pass the longer wire. You use a sin wave as signal, therefore the longer wire causes a phase shift. The phase ...
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2 votes
Accepted

Name of RF demodulation technique using a demultiplexer

Tayloe detector, can be made with 1:2 demultiplexors or 1:4 demultiplexors in typical configurations, it does require an accurate quadrature clock.
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1 vote
Accepted

How to include magnetic loss in transmission line equations for coaxial cable?

Copied from my comment above: In the process of writing out my question, I found the answer... magnetic dissipation needs to be included in the resistance-per-unit-length term (\$R\$). The additional ...
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3 votes
Accepted

RF impedance matching other than 50 Ω

To sum this up, I can design the antenna with 1.5 kΩ to match the IC input impedance of 1.5 kΩ. I understand 50 Ω would be needed if I were using a 50 coax or stripline, but the trace is around 1 inch....
  • 52.5k
0 votes

RF impedance matching other than 50 Ω

If you place a 50 resistor across the connection point or across the input to the chip, you will be fine. You definitely need the 50 ohm termination for maximum power transfer. Edit: Impedance of free ...
  • 3,489
1 vote
Accepted

Need a simple way of generating/transmitting roughly 2.4 GHz (unmodulated), ideally at over 20 dBm (0.1 W)

One option that could be interesting would be to use a bluetooth transceiver (like nrf52840) and put it in test mode. This will allow you to transmit unmodulated 2.4Ghz signals that can be turned on ...
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2 votes

Need a simple way of generating/transmitting roughly 2.4 GHz (unmodulated), ideally at over 20 dBm (0.1 W)

There are transceivers out there that can transmit and receive ASK modulated signal, though I don't think they go to such a low symbol rate. Don't expect long range with such a setup, the 2.4GHz band ...
  • 6,798
0 votes

Small-signal RF amplifer limitations

Center your Vout (which is VRC in this case). For temperature stability, ensure VRe is no greater than 1V. In your case, Vbe is 0.7v, which is fine. That makes VR2 1.7v and VCE 5.8v. I will probably ...
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0 votes

Cost effective way to generate THz frequency

You can't get amplifiers in the THz range; you can generate THz signals using non-linear elements (basically diodes) -- note that this is quite inefficient (worse than -10 dB per stage), and needs ...
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0 votes

Small-signal RF amplifer limitations

This does extend as I am trying to amplify an incoming AM RF signal and have been unsuccessful. You would want to use an amplifier with a tuned input- and output-coupling sections then - otherwise ...
2 votes

Cost effective way to generate THz frequency

There has to be distortion happening, otherwise there would be no multiplication. A frequency multiplier works by generating harmonics through distortion and then selecting one of the harmonics with a ...
  • 6,601
2 votes

How or why are powerful but low-frequency radio waves, such as from a radio station or cell tower, potentially dangerous?

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. All radio waves - even those ...
  • 52.5k
1 vote

Methods for matching networks for high power RF

What sort of components are useful for matching at this frequency and power level? 400 kHz has a wavelength of 750 metres and, given that it's likely you will come close to one-tenth (a rule of thumb)...
  • 396k
1 vote
Accepted

NRF24L01: SPI communication only writes zeros to registers

The following Posts in ST forum here and here recommend to perform the data write and access to SPI_DR register in the following Way: ...

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