Topband: Shared Apex Loop Array

[bruce whitney]

James,
Thank you for your observations and recommendations. I respect and appreciate the wisdom. However, I think I will get up close and personal with the modeling software and see what I can learn. Maybe it is possible to substantially kill more of the high angle response, as the verticals do 'for free.'. 
73, Bruce W8RA
 
 
 

________________________________
 From: James Wolf <jbwolf at comcast.net>
To: 'Topband Reflector' <topband at contesting.com> 
Sent: Monday, February 10, 2014 5:29 PM
Subject: Re: Topband: Shared Apex Loop Array
  

The antenna geometry indicates that it should perform similar to a Waller
Flag *under the same conditions*.  The Waller flag though, (as Tom has
alluded to) has more spacing between the loops and is usually mounted higher
in the air.  Height above ground is important.  Raise your model up to 100
ft.
Also, since the currents in the center vertical wires are out of phase, you
should be able to eliminate three of those wires. Tie all the wires together
at the top and at the bottom, and use just one wire from top to bottom.

Jim - KR9U

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Andy Ikin
Sent: Monday, February 10, 2014 4:12 PM
To: bruce whitney; Topband Reflector
Subject: Re: Topband: Shared Apex Loop Array

Bruce,

I have considerable experience with loop arrays; whilst they are good
performers in an electrically noisy environment, they suffer from poor
directivity at higher angles. This can also be seen with EZNEC models by
looking at the AZ Plot with an Elevation angle of  say 40 degrees.
The directivity and RDF is much better with a pair Phased Flags for example.

Other issues, Tom has mentioned a too close element spacing which will lower
the array gain. Also there is the issue of array stability i.e. a minor
phase or amplitude error will completely screw up the pattern.

73

Andrew  G8LUG




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