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[TowerTalk] Fw: [SteppIR] 3El height

To: <>
Subject: [TowerTalk] Fw: [SteppIR] 3El height
From: "Al Williams" <>
Date: Fri, 28 Jul 2006 09:12:58 -0700
List-post: <>
No one on the SteppIR yahoogroups forum has responded to my posting.  Maybe 
some Towertalkians are interested and knowledgable?

----- Original Message ----- 
From: Al Williams 
Sent: Thursday, July 27, 2006 1:10 PM
Subject: Re: [SteppIR] 3El height

Jerry, k3bz, sets forth an interesting concept that tuning the SteppIR elements 
may somehow change the vertical angle of maximum radiation for Yagi type arrays.

For some time I have been trying to understand why/how Yagi antennas provide 
directional gain. In going through about 20 antenna books written for the ham 
community, only one offers what appears to be a technical explanation. This 
book is Lawson's "Yagi Antenna Design", but its explanation uses too much 
trigonometric formulas for me to wade into. All other books limit their 
explanation to two factors: 1. that the 
magnetic field caused by current in a antenna causes an induced current into 
adjacent wire/elements which then radiates its own electromagnetic wave. 2. The 
electromagnetic wave from this adjacent element adds to the electromagnetic 
wave from the driven element
which results in a composite wave strength at distant receptions. The composite 
wave strength may be greater or less than that from the driven element alone 
depending on the phase difference between waves at the receiving site.

The phase difference is caused by three factors: 1. The distance/time to the 
receiving site from the driven and the induced elements signal.
2. The phase difference in the induced element causes am 180 degree lag of 
induction plus a phase shift if the adjacent wire is not resonant.
This non resonant adjacent wire appears to answer why a reflector is longer and 
a director is shorter than the driven element.

3. The third factor is the phase shift caused by a distance/time of the parts 
of the wave being (reflected/reradiated?) from the source on its journey to 
receiving site. Note that I haven't mentioned the angle of reflection here!

Now, I think that Jerry is suggesting that this third factor can be compensated 
for by adjusting SteppIR's element lengths.

Well, why not??????


BTW Why does a dipole have a directional pattern? 

----- Original Message ----- 
From: Bill Tarkington 
Sent: Thursday, July 27, 2006 11:05 AM
Subject: Re: [SteppIR] 3El height

FWIW, I use my 3L at forty feet due to lot size limits, and it works on 20 
quite well. Better than I had ever hoped!
----- Original Message ----- 
From: Jerry Keller 
Sent: Thursday, July 27, 2006 11:33 AM
Subject: Re: [SteppIR] 3El height

With respect, I have to disagree with Mike on this. The SteppIR 3L works 
great on 20M at 40 feet. In fact, much of the design and testing was done at 
about that height. The great thing is that, although 40 feet might not 
always be the best height for a fixed monobander, much of that is overcome 
overcome because the SteppIR is tunable. I bet half the 3L users out there 
are closer to 40 feet than to 55, and some are much lower and still get 
excellent performance. I know I do.
73, Jerry K3BZ
----- Original Message ----- 
From: "Mike K6BR" <>
To: <>
Sent: Thursday, July 27, 2006 10:46 AM
Subject: RE: [SteppIR] 3El height

I would say 55 feet is minimum for 20 meters; if you don't care about 20
meters have the beam lower.


I have started stacking the tower. What height is ideal for the 3 El
beam. I'm at 40 feet now shoud I go another 10 feet or stop now.



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