[Towertalk] Loop Gain (was LPA designs)

[EUGENE SMAR]

TT:

     FWIW:  Back in the late 80's I was involved with designing a relay
station for VOA in the Negev Desert in Israel.  The intended application was
to receive satellite-borne audio from Washington DC studios and retransmit
the material to south-central Asia (Afghanistan, Kyrghystan, Kazahkstan,
etc.)  The US-based transmitters couldn't broadcast to that area directly
due to Soviet jammers.  The main transmit array was a series (three, I
think) of curtain arrays that could be slewed a few degrees in azimuth and
elevation by changing the phasing of the feeds.  The arrays were to be
supported between towers that were three hundred feet tall.  (Antenna area
was measured in acres, not square feet!)  I believe Saber was the intended
manufacturer, but I could be mistaken.  The transmitters (Continental among
other mfrs) were going to be 100 kW jobs and the ERP was enormous (I can't
recall the figures.)

     The site was also going to include a large LPDA for 6 - 30 MHz up at
100 feet on a rotator (SS, here I come!)  This antenna was a backup for the
programming, in case the satcom feed failed.  It was also going to be used
with a "QRP" 50 kW transmitter for order wire comms for TTY and who knows
what else.

     The whole thing was going to be computer-driven based on propagation to
the intended target sites and the program schedule.  So basically I know of
at least one SW broadcast facility that included both curtain arrays and
LPDA's in its antenna line-up.

73 de
Gene Smar  AD3F
P.S.  Then glasnost came along and Mr. Gorbachev silenced the jammers.  The
project was never constructed.  Sigh.
-----Original Message-----
From: Pete Smith <n4zr@contesting.com>
To: TOWERTALK@contesting.com <TOWERTALK@contesting.com>
Date: Saturday, November 16, 2002 2:44 PM
Subject: Re: [Towertalk] Loop Gain (was LPA designs)


>At 11:28 AM 11/16/02 -0600, Jon Ogden wrote:
>>on 11/16/02 10:49 AM, Zyg Skrobanski at af4mp@mindspring.com wrote:
>>
>> > I don't think I've seen Yagi's used by any SW broadcasters.
>>
>>Probably not.  It's too narrow in bandwidth and probably too directional.
>>
>
>Actually, when I lived in Taiwan in the late 1960's, there was a religious
>broadcasting station there that used a three-element tribander (modified
>for BC frequencies, I assume) to broadcast to the mainland.  The quad
>parasitic array was, I believe, developed at broadcast station
>HCJB.  Today, VOA et al frequently make use of curtain arrays that,
>depending on their configuration, can be very directional indeed.  One of
>the other things that is (or was) on the F12 web site was N6BT's
>description of using a 21 dBi gain broadcast curtain in a DX contest.
>
>
>73, Pete N4ZR
>Sometimes a tower is just a tower
>
>
>
>
>_______________________________________________
>AN Wireless Self Supporting Towers at discounted prices,
>See http://www.mscomputer.com
>
>Wireless Weather Stations now $349.95. Call Toll Free,
>888-333-9041 for additional information.
>_______________________________________________
>Towertalk mailing list
>Towertalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk