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Author Topic: two antennas better than one?  (Read 5116 times)
KU7I
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Posts: 260




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« on: May 20, 2012, 04:10:30 AM »

I am living in Japan right now. My two story Japanese house is squished in-between all of the other houses. There is barely enough room to put up a vertical and if I do, it will be in the courtyard which is about 18 ft x 18 ft. This courtyard is completely surrounded by houses and a huge Japanese Wolf Spider infested tall hill. I can however put up another vertical on the other side of the house which is also heavily blocked by houses. My question is would it possibly be of any benefit at all to put up two identical verticals and feed them in phase? I would be thinking more of diversity reception/transmission and obviously not along the lines of gain. One would be on one side of the house and the other one the other side of the house. They would be totally blocked by the house. Just curious. Lane Ku7i Yokosuka, Japan (JA call pending). US Naval Hospital Yokosuka.
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WB6BYU
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Posts: 17192




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« Reply #1 on: May 20, 2012, 11:06:00 AM »

There might be.  If you do put them up, I'd start by comparing the two antennas
to each other.  One might pick up a lot more noise than the other, for example.
(They don't have to be identical - this is a good step for any sorts of antennas.)
You may find that one is always better, or at least never worse, than the other,
in which case that is the one to use.

True diversity systems require the use of dual receivers, often feeding separate
headphones of a stereo pair.  That allows the human ear to extract the information
from whichever side is best at each instant.  But you can try phasing them - for
example, by building a box that allows you to vary the relative phase (perhaps in
30 degree steps) and seeing how it affects received signals.  It might or might not
give any improvement, depending on the circumstances.
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KU7I
Member

Posts: 260




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« Reply #2 on: May 20, 2012, 12:29:18 PM »

Okay Dale, thanks for the info. The first antenna to go up is a 36ft vertical dipole fed with 300 ohm twin-lead. It will only be about 4 to 5 feet from one corner of the house. I wish I could get it further away but there is no way.

I was hoping to be able to put up a 30 meter or even a 40 meter horizontal loop on the roof but I need a very big ladder to get up there. Will try the vert. dipole first but I expect it to be quite noisy.

Lane
Ku7i
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