Mike: You will need more than "a few tens of acres" for rhombics, their
beamwidth is so narrow that you will need an array of them. The
transmit site for KOK ["Los Angeles Radio" now SK and demolished] was
probably at least a square mile, likely more. Rhombics for the
point-2-point services, horizontal V-beams for the maritime service.
VOA was partial to Sterba and other "curtain" designs. Similar to
rhombics in the gain and main lobe elevation departments, they exhibit
wider beam widths which was good for broadcast to specific areas instead
of specific cities. VOA had a large station in Dixon CA with multiple
curtains which is gone now. The one in Delano CA was still there
[inactive] last time we drove down CA99 to Bakersfield 5 or so years
ago. They do require two or more very tall towers however.
There's a trade-off equation. Rhombics are quite simple and do not
require massive towers. They DO require a lot of land which must be
factored into the total antenna cost. That land has to be kept clear of
major vegetation too. Curtains take less land but are substantially
more complex and more difficult to erect, inspect, and maintain. It
always comes down to money. [:-))
Don Wallace, W6AM, was a legend on the west coast in the 40's/50's. His
QTH was in the Palos Verde Hills [west of downtown Los Angeles]
overlooking the Pacific with multiple rhombics. At that time, transmit
power was measured by plate input power and our limit was 1 KW. W6AM
had separate Collins KW-1 transmitters permanently tuned for each band,
all the feedlines were open wire, and he basically talked to anyone he
wanted to. I got a chance to visit the station as a teenager with a
group ... had to ask my Elmer about the looong wires about 8 ft off the
ground ... beverage RX antennas under and around all the rhombics.
73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County
On 9/13/2019 3:24 PM, Mike Markowski wrote:
Can you expand on this, Ken, or if easier, a reference? I'm curious
what tradeoffs are made. I used a rhombic at Ft. Monmouth, NJ before
the Army base was closed in 2011, and used to boom into Europe and
Russia. It was amazing. I also got copies of WWII manuals on rhombic
construction while there. You know, just in case I became wealthy
with tens of acres of land. :-)
73,
Mike ab3ap
On 9/13/19 5:57 PM, Ken G Kopp wrote:
Rhombic antennas derive their well-known gain by "throwing away" some of
the design's gain. Ditto for the infamous "inverted vee". Use is
made of
the lobes from the four wires while disregarding others.
73 !
Ken Kopp - K0PP
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
