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[TowerTalk] The best stacking distance for long-boom yagis- 0.5 waveleng

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Subject: [TowerTalk] The best stacking distance for long-boom yagis- 0.5 wavelength!!
From: (Bill Tippett)
Date: Sun, 29 Jul 2001 13:48:10 +0100
Hello Tonno, Jiri et al!

        I was curious about your statements:

Tonno ES5TV wrote:

>Maybe I should have emphasized in my post that I wanted to find the best
>stacking distance for contesting! Not to maximize F/B definitely.

        What are you trying to maximize for contesting?  Several years ago
I was of the opinion that poor F/B was actually desirable for contests,
especially when I was using only one antenna.  Having used my stack for a
couple of years, I now believe F/B is more important.  My reasoning is that
I believe a good pattern (F/B) is extremely important for hearing the very
weak stations better in heavy QRM.  If I want to hear in another direction,
for example EU and SA, I am more likely to spray my transmit signal to
cover both areas on transmit, but then listen only in the desired direction
for very weak signals by switching on receive.  The same may apply to
takeoff angles...I want to maximize my vertical angles on transmit, but
then I want to select the best combination to hear very weak signals.  I
think you are saying maximize for angle coverage but why not better F/B

Jiri OK1RI wrote:

>2.ON HF I am sure that this is only one - less important point, what you
>really want to do is to cover as many vertical angles as possible. To
>achieve this you need to have the antennas closer.

        I also don't understand how moving antennas closer maximizes
vertical angle coverage...I think this would make the vertical angle smaller
(centered for the height of the stack midpoint).  I prefer a stack with fairly
wide vertical separation.  If signals are extremely low angle, the full
3-stack or top 2-stack combination will be best.  If signals are fairly
high angle, the lower 2-stack will be best.  If signals are very high
angle, the lower antenna alone will be best.  Maybe you are talking about
always using your stacks as full combinations and not switching them as I
do using the StackMatch (any combination of the 3 antennas).  Is that what
you mean?

        In my opinion the most important parameters to maximize are as
follows (approximately in order but #1 and #2 are very close):

1.  Azimuth angle coverage (not just beamwidth of a single Yagi but also the
ability to spray in multiple directions simultaneously)...this can of course
be accomplished by being able to independently rotate antennas in a single
stack or better yet have another separate set of antennnas that can easily
switched/combined for other directions.

2.  Vertical angle coverage (transmit with a broad vertical angle but switch
on receive to optimize S/N for weak signals).

3.  F/B or pattern of the array is very important when trying to optimize 
S/N when receiving weak signals.

4.  Forward gain is least important!  When 10M is wide open, a dB or two
is insignificant (S9 + 40 dB versus S9 + 41 dB).  This is also why guys 
who run illegal power are really wasting their efforts in the wrong area

        I would be curious to know your thoughts on the above.

                                                73,  Bill  W4ZV

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