3 ms·
Back in 60's AT&T make lots and lots of circular waveguide, intending to bury it across the country. One of the circular modes is dispersionless; then fiber wa
by madengr 11y ago
Back in 60's AT&T make lots and lots of circular waveguide, intending to bury it across the country. One of the circular modes is dispersionless; then fiber was invented; lot's of money lost on circular waveguide.
Interesting that mmWavguide is still rectangular. Wonder if one could do a mmWave fiber? Don't see why not.
- walrus01 11y agomillimeter wave waveguide on the rear of a parabolic antenna (30, 60cm dish) is actually circular (cylindrical), supporting dual polarity operation (opposite H and V). Individual radio heads like this russian radio or other 80 GHz radios are still single polarity. In certain scenarios you can mount two radio heads on a T-shaped waveguide on the rear of one dish antenna, one in H, one in V.
- madengr 11y agoThanks for the info. I got to mess with W-band stuff years ago, but I'm mostly Ku and below now. Would love to tear down some 80 GHz hardware. Have you seen anything come of the "angular momentum" polarization discovered a few years ago? Seemed specific for P2P microwave.
- walrus01 11y agoI've yet to see a product of any sort I can buy with a credit card or purchase order. Would also like to know if anything comes of it.
- wrigby 11y agoI would love to hear more about that - have any links? From a quick google, all I can dig up makes it sound like it's normal circular polarization, which is used quite often in satellite. Not sure why it wouldn't make it into terrestrial, since it has some interesting advantages (no x-pol alignment issues!)
- madengr 11y agoGoogle "angular momentum antenna". IEEE had a write up a few years ago, but details still lacking. It was simple as twisting the dish surface into a helix, but they didn't say how many modes could be generated.
- amazon_not 11y agoIs it a Russian company? I only found Estonian and Swedish contact details on their website. Both countries are very much not Russia.
- walrus01 11y agoYes elva-1 is a Russian company, most likely they're trying to obfuscate that on their English language web presence. It is sort of a shame because they are just as competent as many of the California based microwave engineering firms, and have been around for 25+ years. Their roots are in military radar systems much like some of the Israeli RF companies (Ceragon, etc).