Posts tagged RF

Synonyms: radio-frequency radio-frequencies

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What is considered RF (radio frequency) is somewhat controversial in the literature.

At one extreme position there are authors that consider RF any part of the EM spectrum where radio transmissions can be implemented, and so they conflate it with the concept of radio spectrum, i.e. from $\pu{3 kHz}$ to $\pu{300 GHz}$:

On the other hand there are people that consider RF a more restricted range, excluding the lower part of the radio spectrum (audio band and below), and so for these people RF ranges from $\pu{30 kHz}$ to $\pu{300 GHz}$:

Radio frequency on Wikipedia.

There are other authors, who take a more pragmatic approach and consider RF only the part of the radio spectrum for which lumped-element analysis and design techniques can be applied in a practical way, so from about $\pu{30 kHz}$ to about $\pu{3 GHz}$ (someone puts the upper limit at $\pu{300 MHz}$, someone at $\pu{1 GHz}$ ), hence excluding most part of the microwave bands.

In fact, for microwave systems lumped-elements circuit techniques often fail and special techniques based on Maxwell's equations must be employed. And for very low frequencies, although lumped-elements techniques can be used, the structures (e.g. antennas) become unwieldy because of the extremely long wavelength ($\pu{100km}@\pu{3kHz}$ in vacuum), so they require special technology.

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Q&A How to protect RF switches from ESD?

Assume that I have some generic antenna connector, followed by a pi-filter/50ohm impedance matching components, then a DC blocking cap (as per the RF switch recommendations) and then a RF switch fo...

4 answers · posted 1y ago by Lundin‭ · last activity 6d ago by Nick Alexeev‭

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Q&A How to calculate the RC filter of a TCXO for a RFIC reference?

I have a 30MHz TCXO circuit (TCXO datasheet) like this serving as local oscillator to a RFIC: The RFIC manufacturer recommends to "add filtering caps" for high RF output cases. That is >20d...

1 answer · posted 1y ago by Lundin‭ · edited 2mo ago by Lorenzo Donati‭

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Q&A What effect will extreme temperatures have on characteristic impedance of a wire?

My scenario is this: radio equipment controlling an overhead crane inside a steel mill. Specifically it is used for transporting melting pots. With the current, unfortunate installation, the antenn...

2 answers · posted 1y ago by Lundin‭ · last activity 2mo ago by Lorenzo Donati‭

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Q&A micro-RF connector crimping options

Do micro-RF connector mating crimp connectors are ever sold separately together with a crimp tool? For example this I have looked through a lot of pages, and can only find PCB connectors + cable a...

1 answer · posted 4mo ago by Elleanor Lopez‭ · last activity 4mo ago by DSI‭

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Q&A Is there a way to reliably measure antenna return loss outside a lab?

Assume I'm a complete beginner at RF. Is there a way to measure return loss of an antenna, in such a manner that I can reliably reproduce the measurement later on? What I'm talking about is produ...

2 answers · posted 2y ago by Lundin‭ · last activity 1y ago by TonyStewart‭

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Q&A Location of AGC in a superheterodyne RX chain

RF novice here. If using a superheterodyne receiver for the purpose of FM/FSK modulated signals, I'm wondering if the location of an optional automatic gain control (AGC) circuit is always placed o...

0 answers · posted 1y ago by Lundin‭

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Q&A Most correct term for radio switching noise?

I'm wondering what's the most correct term (if any) to use for "switching noise" of a radio transceiver? By that I mean the spikes that originate from turning the power amp on/off while switching b...

1 answer · posted 2y ago by Lundin‭ · last activity 2y ago by Olin Lathrop‭

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Q&A Why are antenna PCB traces square instead of rounded?

While doing some reading on RF designs I ran across this paragraph: I have never designed an RF circuit, but all the PCB trace antennas I have seen on development boards are square. For example,...

2 answers · posted 2y ago by Kranulis‭ · last activity 2y ago by TonyStewart‭

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Q&A Microwave oven interfering with WiFi on the 2.4GHz band

As I understand it, microwave oven magnetrons operate at 2.45GHz, which is an unlicensed band in most of the world. When 2.4GHz technologies such as WiFi (802.11), Bluetooth and Zigbee were launche...

2 answers · posted 3y ago by Lundin‭ · last activity 2y ago by TonyStewart‭

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Q&A Filter RF Harmonics With Additional PI Network

I have a 900MHz radio with a reference design matching network. The radio feeds to a PCB antenna (PCB antenna hasn't been verified with a VNA, and may not be a great match; this is a project to n...

2 answers · posted 2y ago by leroy105‭ · last activity 2y ago by leroy105‭

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Q&A Mixers and Audio Extraction in a DCR Architecture

I want to make a simple 7MHz direct conversion SSB receiver in order to materialize some RF concepts I have been teaching myself lately. My question revolves around the mixer portion. I'm failing t...

1 answer · posted 3y ago by jm567‭ · edited 3y ago by jm567‭

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Q&A Antenna Feed Line Question

Hello, I am designing 1/4 WL strip antenna for a bluetooth chip and i had some questions regarding the 50 Ohm feed line. Right now I am using a Nordic-recommended 1.5mm trace width and a 23mm + 4mm...

1 answer · posted 3y ago by jm567‭ · last activity 3y ago by Olin Lathrop‭

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Posts tagged RF

Synonyms: radio-frequency radio-frequencies