HFU HF Underground
General Category => General Radio Discussion => Topic started by: NQC on May 12, 2021, 1238 UTC
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Hey All,
LONG shot on this one- but :
I am wondering about pics I saw MANY,MANY years ago of an antenna in Israel. (If we could , please leave politics and "current events" out of any replies- strictly a technical discussion -thanks).
I believe that the Israelis had a "hardened" antenna (if I recall correctly) for AM broadcast. It consisted of heavy steel I beams welded in series stood off on large insulators , very close to the ground (6' up ?) .There may have been protective earthen dikes around it as well.
Probably a miserable pattern for local ground wave but maybe via NVIS- MAYBE ?? . But if one really cranked up the juice then tuned and loaded it properly, I suppose it COULD ground wave "radiate" MAYBE enough to cover a limited area ( ie maybe just around Tel Aviv ?). If nothing else, a fascinating technical concept (re being bomb "resistant"), even if it was a real dog re power in vs. power out. Transmitter was likely in a bunker.
I can't find a THING about this online and I can only imagine it may be long gone by now.
It also seems that Israel in general is now completely off of the AM broadcast band for ALL (ALL) outlets and that Kol Yisrael is also long gone off shortwave ( anyone ,any info ?).
Israeli Army Radio / Galgalatz now seems to be on FM only as well. Not sure if the I beam antenna was theirs or not for civil defense purposes. Also WAY, WAY back in the day, I THINK they were also on shortwave, maybe using SSB (anyone, any info, frequencies used /mode ?).
I have personally seen "a sort of" "hardened" antenna on the Maginot Line Fortifications near Bitche, France. Large steel brackets on a vertical wall held a large gauge long wire antenna on heavy insulators. Certainly not nearly as beefy as an I beam antenna, but "tough enough" against small arms fire ( I guess) .
de K
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Israeli Army Radio used to be a regular here on 6973, I was sad to see them go. Great propagation beacon, and who could resist Hebrew covers of cheesy 70s pop music? :)
There's a few logs of them on the SWBC forum here, up to the end of 2012: https://www.hfunderground.com/board/index.php/board,4.0.html
Looks like they moved to 6885 at one point to avoid Chinese jamming.
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Hey Chris ,
Thanks for the info.
K
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I believe that the Israelis had a "hardened" antenna (if I recall correctly) for AM broadcast. It consisted of heavy steel I beams welded in series stood off on large insulators , very close to the ground (6' up ?) .There may have been protective earthen dikes around it as well.
I would wonder if you go to that length, whats to keep someone (with lots of money) from floating an entire building an using that as an antenna? Maybe a watertower?
During WWII, many domestic AM's that were considered "essential" built fortifications around their tower bases to keep the enemy from shooting out the insulators and bringing the tower down.
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It also seems that Israel in general is now completely off of the AM broadcast band for ALL (ALL) outlets and that Kol Yisrael is also long gone off shortwave ( anyone ,any info ?).
This website indicates KOL stopped broadcasting on shortwave in March 2008 with an exception of a Farsi service transmission to Iran.
http://mt-shortwave.blogspot.com/2008/03/last-days-of-kol-israel-on-shortwave.html
I went through my archives and found Prime Time Shortwave English Broadcast Schedules for B11 which included a WRMI relayed 15 minute broadcast of KOL in English at 0645 utc on 9955am. WRMI probably streaming (or rebroadcasting podcast) KOL as they do now with RAE and others.
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).
I have personally seen "a sort of" "hardened" antenna on the Maginot Line Fortifications near Bitche, France. Large steel brackets on a vertical wall held a large gauge long wire antenna on heavy insulators. Certainly not nearly as beefy as an I beam antenna, but "tough enough" against small arms fire ( I guess) .
de K
Well, if it was a hardened antenna on the Maginot Line it was the only thing about that fortification that worked. :D
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The ICBM sites had hardened antennas.
https://www.nps.gov/parkhistory/online_books/mimi/hrs2-4.htm
(Scroll down to the section “Communication Antennae”.)
https://minutemanmissile.com/uhfradio.html
http://www.wa5vjb.com/references/underground_military_silo.pdf
https://forums.qrz.com/index.php?threads/underground-medium-wave-frequency-antenna-at-former-minuteman-iii-missile-alert-facility.708723/
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Hey All,
Thanks for the responses.
NJQA: I had heard about vertically buried / explosive charge activated "Pop Up " antennas underneath pineapple field(s) in Hawaii used at "certain facilities " . Details unknown.
K
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Look for DDR antennas. They are antennas made with a ring of pipe very low above the ground. The simplest form is almost one quater wave long, one end direct to the ground, the other via a VC. Coax connected with a gamma-match near the grounded end.
Designed in the 1950s as SW antennas for war ships. But larger versions seem to have been built on land, to be ready for nuclear war ? (photos on Internet, but not all story is disclosed)
There were versions for amateur use in HF. Now outdated, lots of drawbacks, including a very narrow bandwidth on low HF. But a 27 or 28 MHz version built on a flat rooftop, simpler without VC, could be interesting.
edit : the acronym is DDRR, but it's a misnomer.
A 7 Mhz version (above a lawn) was in the 1974 edition of the ARRL Antenna Book
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What y'all describe sound like the 160MHz antennas mounted on the roof of a train, and other type of railcar. Kind of looked like a large handle than an antenna.
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Hey All,
Ray : DDR design is interesting , never seen that one.
Dood: I have seen train antennas like that.
Still learning.
K
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You might look into DOD hardened communications systems such as:
Survivable Low-Frequency Communication System (SLFCS)
Ground Wave Emergency Network (GWEN) (AN/URC-117)
USAF SAC's "Green Pine" Northern Area Ultra High Frequency Radio System (488L)
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Hey Poacher,
Very in interesting info especially re SLFCS (which I had not heard of ) and GWEN which I had heard of and remember when IT was up.
A bit OT , but FWIW, I was assigned to the CSS in Germany, not DIRECTLY involved in SIGINT, but as a support of it.
But there was plenty of "side action". For reasons I do still do not understand , I was allowed to build my own personal listening post IN the barracks. It included outdoor smaller U/VHF AM/FM, a large (successful) "trans Atlantic" VHF low band antenna and HF antennas (on R-71a , R-70 ,etc). It was amazing how much "open mode" traffic there was - IF you knew where to look.
I was ALSO allowed to do the SAME thing in the barracks while at a previous posting in SC ( 100 ft long wire with Rhombic antennas suspended underneath- for U/VHF/AM FM "SIGINT" and TV Dx), mostly using the same rigs as above.I was actually able to locate an intelligence "entity" close by on my installation that was still using CW ! That's ONE way to "hide" (I guess ???).
During exercises in SC I used to set up a hidden UHF aero receiver at work on our local tower UHF frequency listening for "hostile" call signs on approach. I'd quietly don my gas mask a full minute before the "surprise" attack. Folks never figured out how I did it :).
All happened a million years ago, I imagine things are different now.
K
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Thanks for sharing NQC...Very interesting. So much for Cold War SIGINT COMSEC, based on your experience! Well played.
Appreciate you posting this thread.