The normal minimum size of a rhombic is four wavelengths on a side, with a 60 degree angle at the apex and 120 degree at the sides. For
80 meters (3.75 Mhz), that covers 1800 by 525 feet. And yes, a line that big is normally copper-clad steel for strength.Depends. Receiving rhombics usually use a common resistor (carbon comp is OK at this freq, but a metal film would be better) in a minimalist weather protection device - I've seen everything from a porcelain tube formerly used for knob-and-tube electrical wiring up to a NEMA enclosure mounted on the far mast. All of the transmitting rhombics I've seen use a chunk of transmission line, usually running above ground on supports under the center axis of the antenna high enough to let the cows graze underneath without getting zapped. Somewhere I've got charts showing attenuation version frequency verses wire size for steel and iron wire in open twin lead form. For #10 AWG, that's about 8.0 inches center to center. For 100 KW, that's 7.75 KV at 12.9 Amps. Mind the zaps please.
No, I don't think so. It was located between the highway and the coast, but the antennas were quite different. I recall two enormous VHF broadside arrays - I dunno, maybe 60 elements wide, and ten tall pointing in the direction of Hawaii - up fairly close to the road, and maybe four long wires or rhombic pointing in the same direction. They were in the aeronautical band (118 - 136 MHz), as well as a half dozen HF freqs from
3.47 to 17.91 MHz I've looked through my old aeronautical stuff, but they don't give me coordinates. I'm pretty sure it was close to San Gregorio rather than up towards Half Moon. I've got some ancient maps, and it doesn't look as if there is room for a rhombic in to many places.That wouldn't surprise me. I've got friends who were working at Ames who were commuting from Piller Point, while other are commuting from Los Banos.
East of the Bayshore, between San Antonio and the Embarcadero - know it well.
I didn't have any high power dummy loads, but I always had attenuators which worked just as well.
Old guy