Ik kreeg deze email discussie bij de TCA binnen, leek me wel interessante stof (Onderste mail eerst lezen):
This RA band was the purpose of the obscure electromagnetically tuned Raytheon 6177 CW magnetron. A little voice coil type arrangement flaps a capacitive plate back & forth on the end of the resonator straps to tune the tube
I'd almost forgotten that RAs happened on that band, I thought 13.3GHz was the main band these days
Dan Stocks (TCA), Australia
[Dan is specialist on radar, magntrons and klystrons, Tidak Ada]
From: email@example.com <firstname.lastname@example.org> on behalf of Ludwell Sibley <email@example.com>
Sent: Wednesday, 19 January 2022 4:11 AM
To: firstname.lastname@example.org <email@example.com>
Subject: [tubecollectorsassociation] The Rumble Over 5G and Radar Altimeters
This is a “tube matter” because of the wide use at one time of GE and Eimac ceramic planar triodes in altimeters at 4300 MHz.
The news reports the airline industry Excreting Masonry Units because cellular carriers want to start 5G service at 3700-3980 MHz. If so, it’s going to bring a “catastrophic disaster” for safety.
So where were these guys and the FAA when AT&T was modernizing its TD-2 microwave network? A fully equipped station had 12 transmitting amplifiers for each direction (10 working, 2 protection, or 11 working, one protection) upgraded to five watts each, at 3710 through 4190 MHz, with a couple of decibels of loss in the combining filter and waveguide, then blasted out through about 40 dB of antenna gain. The station was shooting narrow beams that could intersect flight paths, even slightly beyond the horizon. The beam wasn’t direct upward, but neither is the 5G operator’s signal.
The TV broadcast industry was ticked off when the FCC proposed reallocating 3700-3930 from terrestrial microwave and satellite downlinks to 5G use. The airline people probably didn’t think they had a problem and demand the FAA coordinate with the FCC. The FAA seems to be covering itself.
Behind all this, a TD-2 station blasting away on 4170 is a lot closer to the altimeter on 4300 than the 5G operator on 3980.
The cellular operators are probably irritated because of all the money they’ve invested in refitting towers and boating of “nationwide 5G service” to us public. Those consumers who’ve bought new phones will probably be upset because they work only as obsolete “Long Term Evolution” 4G junk near the airport.
It would probably be cheaper to society to replace a bunch of radar altimeters, especially the tube ones, with new ones at other frequencies.
It’ll be interesting to see how General Aviation will react to this rumble – a lot of private pilots probably have radar altimeters too.
Ludwell Sibley, TCA,
[Ludwell Sibley is Founder and chairman of the TCA, Tidak Ada]