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Author Topic: Short 160 Meter Antenna  (Read 1542 times)
KU4QW
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Posts: 6




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« on: December 10, 2004, 11:04:00 AM »

Years ago a friend of mine had a 160 meter antenna, it was like a 1/4 wave sloper with a coil on it, coax feed  with shield to ground and it was only around 30-40 feet long.  Any idea what this is?  Anywhere on the net I can find plans to make it?
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WB2WIK
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« Reply #1 on: December 10, 2004, 11:14:20 AM »

Alpha-Delta has a model like that, model DX-B or something (check their website).  It's short and heavily loaded, with the resulting extremely narrow bandwidth.*  It's also very inexpensive, and the coil is already wound, and it comes with a feedpoint system: Probably homebrewing the same thing would cost as much as just buying the A-D one.

We tried one of these years ago and it wasn't very satisfactory, but better than no antenna!

(*Extremely narrow: <2:1 VSWR over maybe 15 kHz of the band; <3:1 over perhaps 20-25 kHz; beyond that, it's really way out there.  Kind of like a 160m mobile whip!)

WB2WIK/6
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W0FM
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« Reply #2 on: December 10, 2004, 11:54:16 AM »

Yep.  But a 30-40 foot long "mobile whip".  Shocked)

WØFM
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N6AJR
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« Reply #3 on: December 10, 2004, 12:43:02 PM »

look at the book "top band DXing"  I think by orn
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AC5E
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« Reply #4 on: December 10, 2004, 04:49:28 PM »

From my experience the Alpha Delta DX-B sloper is a durable and modestly priced "get by antenna." Like any heavily loaded wire, it will "work" on top band. If you use the term "work" very loosely - or perhaps I should say I always had to work for every contact I made on one.

The problem is not with the antenna, it's with the whole concept. There still ain't no such thing as a free lunch - and a 60 foot wire on top band makes a poor radiator. Stick a loading coil by any name in the middle and efficeny goes even further down.

But you can make 160 Meter contacts on it - just as you can on a very short mobile whip. And when conditions are just right you may be able to work some modest DX on it. And you can even load it up on 80 with similarly modest results, and 40 and 30 fairly decent results.

So, if that's all you have room for, go for it. If you can manage something better - do it!

73  Pete Allen  AC5E
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K0ZN
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« Reply #5 on: December 10, 2004, 06:24:13 PM »


The ARRL Antenna Book and "Low Band DXing" (which is an excellent antenna book) have/had charts and guides to shortening antennas via loading coils.

Like Pete, AC5E said: there is no free lunch. A "short loaded" antenna will "work" but a bigger antenna is better. Keep in mind, that a 40 ft. long antenna is "tiny" on 160; a 1/4 wave sloper (which would be "full size") is 128 ft long...so a 40' ft antenna is only 30% of full size. Depending upon your situation, LINEAR loading is also an option that is addressed in these books and tends to be a little more efficient than lumped constant loading (a coil). You can also use BOTH linear and lumped constant loading in your attempt to reduce losses. The books address this. If you are limited to the shorter space BE SURE to use large gauge wire and construct the coil carefully and neatly to minimize losses.

73,  K0ZN
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N6AJR
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« Reply #6 on: December 10, 2004, 06:36:38 PM »

short and 160 antenna...is almost an oxymoron, I suppose you could call a dummy load on 160 a short antenna..
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