[TowerTalk] [Bulk] Re: antenna choices for K4XS

[Jim Brown]

On Sun,4/12/2015 7:01 PM, Jeff AC0C wrote:
> The mosleys are popular around the midwest as Mosley is just up the 
> road. And they have one feature that is important here - they have a 
> reputation of staying up in the ice and wind pretty well.  The antenna 
> that stays on the tower in the wx is always better than the one that's 
> on the ground. 

Yep. VERY important, and structural weakness is one of the major 
criticisms of some of the lower cost beams.

Having studied N6BT's book on antenna design, it seems clear that the 
multi-band 2-el Yagis without loading or traps are better performers 
because that loading and those traps lead to losses and reduced 
radiation resistance.

I don't think any engineer who has studied Ward and Steve's work, or who 
has done any serious antenna modeling would be surprised that the 
difference between the best and worst of the antennas in any logical 
group is much more than about 3 dB. But it's that 3 dB that we're paying 
for, whether we buy it or build it!

Except for their ease of installation or ruggedness, there's no brand of 
Yagi that is better for "your QTH" -- they are all a horizontal antenna 
at some height above earth, subject to your terrain. But what matters a 
LOT is what that height and that terrain does to your signal by changing 
relative strength at different vertical angles.

That's what Bill is talking about with HFTA -- it studies a horizontal 
antenna at your QTH, based on terrain data from a government agency 
(USGS?). I used HFTA extensively here. It's why my big tower puts my 
Yagi at 120 ft, and it's why I stopped there -- it told me to do any 
better, I'd have to go to 320 ft or so because of the ridge to the north 
and east of me!

This thread started by talking about cost. Yes, my SteppIR cost me $2k, 
which is in the range of quality new antennas with comparable 
performance. The tower could have cost more, by the time I bought it, 
bought rated hardware so that it can be assembled and guyed safely, pour 
a safe concrete base, and get it all up in the air. I managed to find 
second hand Rohn 25 sections in excellent shape at a very nice price, 
and got a lot of help from my friends, but rated hardware ain't cheap. 
There's coax (350 ft of 7/8-in hard line that I scrounged), a rotator 
350 ft of cable for it, and so on.

So in the big picture, the cost of the antenna itself may not the 
biggest part of the job.

73, Jim K9YC