lowest frequency waveguide ever made?

[CopperCone]

Not counting horn antennas, what is the lowest frequency wave-guide made?

The lowest commercial I found is WR-2300, which is good for 300MHz

What are these used for? Are lower frequency wave guides used for anything? Usually I see high power coaxial line used instead of waveguides, but I figure there might be some interesting applications.

Application of WR-2300
http://slideplayer.com/slide/12972804/

Synchrotron

[Yansi]

Interesting stuff they have there 

[Richard Head]

I can't answer your question unfortunately but I watched a YT video the other day about the Arecibo radio telescope. They use waveguide for their 450Mhz transmitter and it looks like HVAC ducting!

[radar_macgyver]

I suppose it's all relative. Some folks who regularly work on W-band stuff visited my work, where the largest guide we use is WR-284; they looked like they'd seen a ghost.

[dkozel]

Waveguide I don't know, but I've seen coax that I could almost crawl through. This system runs at 233 MHz.

[TheUnnamedNewbie]

I think I have seen some waveguides at FM frequencies. I think the main reason they are used is maximum power, which is limited in coaxial by dielectric breakdown. Losses could also be less of an issue but I don' t know how significant the losses are at these (relative to what I'm used to) low frequencies.

[AF6LJ]

I remember seeing specs for waveguide that was made for 225MHZ, big stuff.

[Wolfram]

Not counting horn antennas, what is the lowest frequency wave-guide made?

The lowest commercial I found is WR-2300, which is good for 300MHz

What are these used for? Are lower frequency wave guides used for anything? Usually I see high power coaxial line used instead of waveguides, but I figure there might be some interesting applications.

Application of WR-2300
http://slideplayer.com/slide/12972804/

Synchrotron

WR-2300 waveguides were used between the klystrons and the accelerating cavities of the LHC at CERN when I was involved with that system, and as far as I know they are still using the same systems. Here is a document with more in-depth info https://cds.cern.ch/record/1287871/files/CERN-ATS-2010-192.pdf .

[AF6LJ]

Thanks that will make for good reading.

[jmelson]

When I worked at NASA Wallops Station, MIT had a big radar they used for space object tracking.
It ran at either 450 or 900 MHz (conflicting online info), and the waveguide looked like industrial-scale air conditioning ducts.

Jon