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Author Topic: All-Band-Antenna Question  (Read 1090 times)
ATLMAGIC
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« on: November 21, 2002, 09:36:04 AM »

I’ve heard that I can run 100 ft of wire to form an all-band-antenna. This would be a good thing ‘cause I’m just starting out (and broke). My question is, do I need some sort of tuning device or can I just connect the antenna and start receiving?

I’m using a 2 meter ht connected to a ½ wave dipole right now. I’d like to get into QRP soon.


Paul Edwards, KG4PWO

Member American Radio Relay League (ARRL)
Member North Georgia QRP Club
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N4UM
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Posts: 466




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« Reply #1 on: November 21, 2002, 08:11:29 PM »

A 100 foot piece of wire fed in the center with low loss commercial ladder line or home made open wire transmission line should enable you to operate from 3.5 to 30 Mhz.  You will need an antenna tuner to keep your transmitter happy by enabling it to operate into a matched load.  A wire about 30 feet in the air should provide you with a low cost antenna that will enable you to make many contacts.
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N3CJN
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« Reply #2 on: November 23, 2002, 11:21:52 AM »

Your message asked if you could just plug it in and start receiving.  The answer to that is Yes!  When
you want to start transmitting, that's when you'll need
a tuner with a ladder-line fed doublet for all bands.

For QRP work only, on a tight budget you could substitute TV twin lead for the ladder-line.  Most twin lead isn't made to handle much xmit power, but 5W or so should work OK.

I used to be a dipole man, and certainly a dipole high above the ground can do a nice job.  But in the last few years I've been taken by full-wave horizontal loops.  If you have a spot for it, you might try
a 40m loop (about 140 feet around, depending on band segment).  When you use it on 20m and up, you get progressively lower main lobes.  So it can work the local region on 40 and DX on the higher bands.

I have a loop up only 17 feet or so (1/4 wave on 20).
Mine is fed directly by coax, but a parallel line would give even better performance (less line loss for the mismatch at the feed).  Anyhow, it works great. In my experience, a low loop really beats a low dipole.  A horizontal loop isn't very directional, but since I'm not turning it, I like that.  But you do need a tuner as a loop's impedance at resonance is about 115 Ohms.

Low-profile, effective, cheap, simple to build.  

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N4ZOU
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« Reply #3 on: November 28, 2002, 09:45:47 PM »

 Here is just the antenna your looking for!
http://www.geocities.com/n4zou/files/zepp.pdf
Also you could build an L-network tuner and simply connect your 100 feet of wire directly to the output terminal of the tuner. Just build the antenna for the lowest band you plan to operate on and use the tuner to operate on that band and above. Good luck and have fun!
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KT8K
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« Reply #4 on: December 12, 2002, 01:07:26 PM »

Personally, I have always worried too much about loss to use untuned antennas.  I've avoided tuners completely by using resonant antennas (wire or tubing) with traps, and had great results.  I haven't done a detailed analysis of where my losses are yet (coax?), but I have always worried about the losses in tuners.  A good tuned dipole/inverted vee/quarter wave vertical with radials on any band will be useable over most if not all of the band without worry.  Anything under a 2:1 SWR is fine in my book, but I do tune them to be near 1:1 where I use them most (or near band-center).

I did see something in one of the forums suggesting that traps cause a lot of loss.  Can anyone reflect on that?  
Tnx es 73 de kt8k - Tim
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KY6R
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« Reply #5 on: December 22, 2002, 10:48:16 AM »

L.B Cebik has a wealth of information on his web site:

http://www.cebik.com

He says that if you only could put up one horizontal wire antenna, you should consider an 88' or 44' doublet. He also has articles on all of the antenna's mentioned in this forum.

I have found that seaparate antennas tuned to resonance for each band is the best, and (for DX) the lower the take off angle, the better. But that's not always practical.

I have used Extended Double Zepps tuned for a single band and up at least 1/2 wave to be the best horizontal antenna that is very easy to build - cheaply, and shows some gain over a dipole.

I have also confirmed that something like the Force 12 Sigma 40XK is an excellent DX antenna - but only if you stick to using it on a single band. Low take off angle - and because its a vertical tuned dipole, no radials and takes up little space. Force-12 has other great antennas like their Sigma 5. Cebik has an article called "Short hatted verticals" which explains why these work so well.

For 20 - 10, my MA5B minibeam, up 1/2 wave on 20M, far exceeded my expectations for DX work. Directivity helps a lot, and the MA5B is a real "compromise" beam, but a good one (although I really don't like traps).

If you mostly care about local (USA) work, then just about any doublet or long wire and a tuner will work "OK".

The Cebik web site is fantastic . .
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KD5IVP
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« Reply #6 on: January 06, 2003, 11:08:13 PM »

Lets assume you're really low budget.  100ft of wire against a counterpoise of say another 75-100 ft. will get you all over the world.  My qrp packpacking setup for the 20 meter band is 33ft. (1/2 wave) of antenna with 17 ft. (1/4 wave) of counterpoise.  I match the impedence to 50 ohms with a very tiny home made tuner, an L-C network (2 parts and free).   You won't have to worry about feedlines in this settup.  Your wire can be strung in a squiggly line off of tree limbs and suspended with fishing line.   I strongly encourage you to build your own tuner.  Tons of info on the web and in the ARRL handbook.   You'll learn just how forgiving things really are in the antenna world.
73
Paul, KD5IVP  
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