Which Direction to Or

Nick Trim

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Jul 24, 1996, 3:00:00 AM7/24/96

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R> From: ric...@earthlink.net (David Rickmers)
>
> Although it may not look good on paper my practical experience has
> shown me that a wire antenna IS directional...on axis, not broadside.
>
I always assumed a longwire antenna would be directional to its
sides rather than toward its ends. Do you mean a longwire running
east/west will be directional in an east west direction?
Why is this?

-- SPEED 1.40 [NR]: Evaluation day 784...

Len Anderson

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Jul 30, 1996, 3:00:00 AM7/30/96

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NT>From: Nick...@fforum.blkcat.com (Nick Trim)
NT>Subject: Which Direction to Or

NT>R> From: ric...@earthlink.net (David Rickmers)
NT> >
NT> > Although it may not look good on paper my practical experience has
NT> > shown me that a wire antenna IS directional...on axis, not broadside.
NT> >
NT> I always assumed a longwire antenna would be directional to its
NT>sides rather than toward its ends. Do you mean a longwire running
NT>east/west will be directional in an east west direction?
NT> Why is this?

A longwire is directional - in all directions - depending on its
physical length versus a desired signal's wavelength. There's no easy
answer to the why of that since it involves a rather involved study of
electromagnetic waves and their effects on conductors. If azimuth plots
of longwire receiving directions versus signal strength, there would be
many bumps of high signal with many notches of low signal all around the
circle for one frequency. At another frequency, the pattern of highs
and lows would be different. That's under ideal conditions with a
perfect ground or no ground. In a practical residence installation, a
partially-conducting ground, nearby elevated utility lines, metal patio
roofs, chain-link fences, etc., modify the heck out of the ideal pattern
and the apparent pattern is just a blobby amoeba-looking thing without
the high ratio of peaks and valleys of the ideal.

As a general rule of "scientific thumb," the longer the better. :)

---
* OLX 2.1 * 1 ... there's always one in every crowd

Daniel Grunberg

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Jul 30, 1996, 3:00:00 AM7/30/96

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And then there's the REALLY LONG wire, the Beverage (sp?). It's several
wavelengths long (or longer), low to the ground, and definitely
directional along the length of the wire.

--
Dan Grunberg Kensington, Maryland USA

Len Anderson

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Aug 3, 1996, 3:00:00 AM8/3/96

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DG>From: ce...@FreeNet.Carleton.CA (Daniel Grunberg)
DG>Subject: Re: Which Direction to Or

DG>And then there's the REALLY LONG wire, the Beverage (sp?). It's several
DG>wavelengths long (or longer), low to the ground, and definitely
DG>directional along the length of the wire.

Ahem...:)...agreed, but the average house-lot owner/mortgager that
also SWLs doesn't have all that much real estate. One wavelength at
6 MHz is about 156 feet; with the average house lot at 1/4 to 1/3
acre, that one wavelength is going to extend beyond a lot's diagonal.
It's out of the question for a condo or apartment dweller.

For some practical directional loop antennas of small size, the 1990
edition WRTH had a good article on "Combatting Interference In Shortwave
Reception With Compact Indoor Directive Antennas" by O. G. Villard, Jr.,
pp 547-553. All of those pictured will fit easily on a small table top.

---
* OLX 2.1 * No sense being pessimistic - it wouldn't work anyway.