[Top] [All Lists]

Re: Topband: Antenna Advice Plus K9AY Questions

To: "Scott WA9WFA" <>, <>
Subject: Re: Topband: Antenna Advice Plus K9AY Questions
From: "K9AY" <>
Date: Fri, 7 Sep 2007 09:38:27 -0500
List-post: <>
Responses to questions from Scott WA9WFA:

> 1.  I only have clear space for a K9AY on the lake side, down the hill 
> from the house.  This spot happens to be the farthest away from the power 
> lines and poles, maybe 100' away from the drop pole.  The hill is open to 
> the North, East, and Southwest.

The primary issue with any small receive antenna is avoiding coupling to the 
transmit antenna and/or other objects that can disrupt the pattern or be 
large noise sources. It is relatively easy to try the antenna in a spot that 
is convenient and see how it works. You might be surprised -- one of my own 
installations was very close to the house and not too far from a power 
distribution pole. Other than hearing my computer monitor a little too well, 
it worked fine. If your handiest spot doesn't work, it sounds like you have 
a good option for a better location. Hills and slopes won't have a large 
effect, and the exact shape of the loop is not critical. It can be warped a 
bit to get it installed on a hilside.

> 2.  How do you think the receive signal strength or signal to noise ratio 
> might compare with the inverted vee?

An inverted vee has only a little directivity, so an RX antenna with a 
cardioid pattern like the K9AY Loop will be an advantage.

> 3.  Can I expect similar spectacular performance on 80 meter cw as well?

Of course!

> 4.  Why couldn't I just attach an Advanced Receiver Research preamplifier 
> to the 160 meter inverted vee to achieve that 1 - 2 S-unit improvement? 
> ARR is suggesting one could see 6-14 db improvement in signal to noise 
> ratio.  Thats 1-2 S-units.

A preamplifier will increase the level of signals AND noise, with no effect 
whatsoever on S/N. The ambient noise on the low bands is what determines 
S/N, not the gain or noise figure of the hardware. An RX antenna with 
directivity is needed to help S/N.

> 5.  I've been pondering a 160 meter antenna configuration that is sort of 
> an inverted L, originating at the base of the tree at the bottom of the 
> hill, a few feet away from the lake.  ...  I have no idea what to expect 
> from such a configuration.

The ultimate rule is that any antenna will radiate, it's just a matter of 
how well. For your tree-supported semi-random inv-L, simply do your best to 
get the vertical portion as high as possible, and try to keep the horizontal 
portion just as high. A drooping horizontal wire on an inv-L will be 
functional, but less efficient than an well-elevated one. Be sure to install 
enough radials!

73, Gary

Topband mailing list

<Prev in Thread] Current Thread [Next in Thread>