Comment by ahartmetz
7 hours ago
If you find that fascinating already... did you know that all cellphones use mechanical filters in the GHz range? They combine very good performance with very low energy consumption.
https://en.wikipedia.org/wiki/Surface_acoustic_wave
https://de.wikipedia.org/wiki/Akustische-Oberfl%C3%A4chenwel... (pictures)
Honestly, the "HF physics is black magic" trope has made me numb to the phantastical contraptions. I appreciate when they look cool, like esoteric orgon wave radiators.
Small note of clarification. HF in a radio frequency (RF) context actually refers to what we would now consider fairly low frequencies between 3 and 30mhz where wavelengths are in the tens of meters. The black magic is mostly in UHF AND microwave regions where wavelengths start to measure closer to the size of circuit elements.
Although I have also heard it said “RF physics is black magic” to cover all the bases
Yes, radio found out naming is hard before software did, in very old times there was High Frequency (HF), but then circuits got fast enough to go higher, oops, ok no problem, let's call the new frequencies Very High Frequency (VHF) whew that was close, but wait they got even faster! Ugh! Ok let's call the new frequencies Ultra High Frequency (UHF), but wait, we're still not in the Ghz range yet! Thankfully they did not keep going to Super Super Mega Ultra High Frequency.
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AFAIK, the black magic factor is much higher for HF electronics than for HF mechanics. It's at least partially because you can build more complex systems with HF electronics. The other difference is that high frequency EM oscillations easily radiate energy in the form of photons, while high energy mechanical oscillations radiate nothing for practical purposes (at least in vacuum), gravity waves if you're being pedantic.