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I think LW transmission antennas are too large to be built bu amateurs



Full verticals, dipoles, Yagis or logs, yes.

Marconi T or L antennas with capacitance hats and loading coils are well within amateur practice on 630m[1] and 2200m, and common from 40m/7MHz on down.

Not very efficient still; an ERP of 1W, as demanded by the 2200m band, can still take a lot of power on a less-than-ideal antenna. Similar story for 630m. (160m and up is usually not so bad, just that even a good Marconi on longwave is still too big for most people.)

But the current LowFER[3] regs limit the transmitter to 1W final stage input power, and a COMBINED feedline and antenna length of 15m. At least allowing amateurs to operate more here would allow more than just extremely low SNR modes like WSPR to be used at any real distance.

[1]https://www.hamsignal.com/blog/dog-days-and-the-marconi-t-an...

and https://vk6ysf.com/t_antenna_arrangment.htm

[2]https://en.wikipedia.org/wiki/2200-meter_band#International_...

[3]https://en.wikipedia.org/wiki/LowFER


Don't see many longwave radio antennas. Here's one in Hellissandur, Iceland. 300kW output power on 189kHz : https://imgur.com/gallery/ruv-189-khz-kVght0A




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