[TowerTalk] Fixed Quads

[K7GCO@aol.com]

In a message dated 29.01.00 18:31:48 Pacific Standard Time, n4kg@juno.com 
writes:
    This is a great Post.  In regard to the loop or Inverted Vee beam 
described below, someone advertised a phasing and matching box for Inverted 
Vee Beams for around $90.  I have one and am going to make a KW version.  
It's fast and simple.  I had the first article in 8/60 QST on the Inverted 
Vee.  I first used it in 1936 and it only took 24 years to get it printed.  I 
used a sloper in 1937.  3 of them as guy wires on a pole.
I never got that printed. 
k7gco
<< 
 Re:  Full  Wave Loop antenna elements   de N4KG
 
 Chapter 4 in the W2PV  Yagi Antenna Design book
 discusses loop antennas.
 
 Table 4.5, estimated gain and self resistance vs shape,
 is especially interesting.
 
 Shape   Sides    Gain     R (ohms)
          dBi
 
 Triangle       3    2.70   105
 Square     4    2.99   120   (same as diamond)
 Pentagon  5     3.10   126
 Hexagon   6     3.16   129 
 Octagon   8     3.22   132
 Circle   oo     3.28   135
 
 The Triangle is obviously the simplest to install from a
 catenary and is only 0.3 dB below the square configuration.
 Pullout ropes at the bottom corners need only be tied off
 at approximately 1/2 the apex height because of the 60 degree
 apex angle.  For a diamond shape, the tieoffs would need to be
 at least 1.5 times the apex height due to the 90 degree angle.
 
 If you have the room to achieve a 120 degree apex angle
 (tieoffs at twice the apex height), with an 85 ft apex, I 
 would recommend a 2L (or 3L) inverted vee Yagi because
 it will have a greater effective height.  40M beams play
 VERY WELL at 80 to 100 ft.
 
 Several years ago, I had a 2L Delta Loop suspended from a 
 20 ft boom at 120 ft, fixed at 60 degrees.  It was a KILLER
 antenna, covering all of Europe, Middle East, Indian Ocean,
 North, Central, and even South Africa.
 
 A 2L Loop or Inverted Vee Yagi can be made reversible using 
 identical elements, each fed with 3/8 WL of coax, and switching 
 both the center and shield of the feedline.  The open 3/8 WL line
 looks like an inductance at the center of the unfed element,
 effectively loading it to look like a reflector.  K1ZZ had such
 a system in place several years ago.
 VERY CLEVER DESIGN
 The best way to avoid interaction is to use Foreward Stagger,
 i.e., place higher frequency elements in front of lower frequency
 elements.
 de  Tom  N4KG

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