[TowerTalk] Horizontal Loop Performance??

[Edward]

I am in Jeddah next to the Red Sea.  

Sent from my iPhone

On Jan 5, 2013, at 18:19, Jim Lux <jimlux at earthlink.net> wrote:

> On 1/4/13 11:12 PM, Edward Sylvester wrote:
>> 
>> Greetings All!
>> 
>> I am in Saudi Arabia and had the opportunity to throw up some wire
>> antennas.  I put up 30' of fiberglass mast on my 25' roof and
>> installed an 80m INV VEE fed with open wire line, straight to tuner.
>> Hears extremely well.  Cannot transmit until I get a license, which
>> is in the works.
>> 
>> I decided to take advantage of some tall coconut trees and installed
>> a triangular-shaped horizontal loop with >700' of wire fed with open
>> wire line, up 35-50', taking into account the sagging.  This goes
>> straight into a 1:1 current balun at ground level.  Coax run is about
>> 6'.  No issues.  Tunes perfectly.
>> 
>> I ran some A/B comparisons with the Inv Vee and determined that they
>> are very similar in performance!
> 
> Which is about what one would expect... both antennas are a decent fraction of a half wavelength in extent (so it's not like an amplified 6 foot whip or something).
> 
> The receive performance is going to be dominated by the atmospheric noise, so whether the antenna has a different gain isn't going to make much difference.  Lots of people use active receive antennas on 160 to good effect, especially as part of a phased array so you can steer the null towards some noise source.
> 
> Where your two antennas may differ is on transmit: one may be better than the other in terms of resistive loss.  They're about the same height above ground (a tiny fraction of a wavelength), they're both horizontally polarized, they've both got a low feedline loss, etc.  I wouldn't expect a huge difference.  If you were comparing the big loop against a loaded 20m dipole, yeah, more of a difference.
> 
> What is your soil like?  Are you in Eastern Province with either sand/rock or with sabkha (the latter is the topband dream substrate)? Or rocks and such.  I doubt there's anywhere in Saudi Arabia with very deep topsoil (in the context of 160m wavelength and skin depth), except perhaps Hofuf in the middle of the Al Ahsa oasis.
> 
> If you are in a coastal area with high salt content and high water table, you might think about a vertical.
> 
> 
>> 
>> I was hoping the Loop would blow away the Inv Vee but was
>> disappointed when this did not occur.  Has this been your experience?
>> I have tried to read as much as possible, but there are varying
>> opinions on loop expectations.
>> 
>> Your opinion would be greatly appreciated.  Frustrated....
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