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[Towertalk] 100M-long boom Yagi for 20M

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Subject: [Towertalk] 100M-long boom Yagi for 20M
From: (Michael Tope)
Date: Sun, 12 Jan 2003 08:26:19 -0800
I run into W6VPH in the hallway at work from time to time. He
has a picture of that 13 element array above his desk at work
and his eyes really light up when he describes the performance.
The array was constructed on top of a mesa in a rural area
south of Los Angeles. He still has the 500' of Rohn 25 used to
support the yagis in storage. These days he is doing satellite and
moonbounce from a city lot in Los Angeles, but he may resurrect
his interest in HF once he retires and moves out to the countryside.

73 de Mike, W4EF.......................................................

----- Original Message -----
From: "EUGENE SMAR" <>
To: "TowerTalk" <>
Sent: Saturday, January 11, 2003 9:09 PM
Subject: [Towertalk] 100M-long boom Yagi for 20M

> TT:
>      I was going through some old mags in the basement today and found a
> couple of articles of interest (I hope) to TowerTalk related to Yagis.
> are both from the June 1991 issue of IEEE's Antennas and Propagation
> Magazine.
>      The first, A Modern Giant Yagi, was written by W6TSW, W6VPH and
> It describes their work on a 13-element, 100-meter long boom (!) Yagi for
> 20M.  The Yagi was constructed on six colinear towers on a hilltop in
> Southern California.  The top guy set of each tower is dielectric
> according to the authors.  One tower supports what looks like a
> three-element 20M Yagi - Refl/DE/Dir 1 of the array.  Each of the
> five towers supports a wide-spaced 2-element Yagi (Dirs 2-11).  The photos
> show all of the booms pointing in the same direction.  The plane of the 13
> elements (tower height) is said to be 25M AGL.
>      Specs are:  fixed azimuth of 15 degrees east of true North (don't
> start!), covering selected portions of Europe and Asia; design freq:
> MHz; predicted directivity: 15.8 dBi freespace/21.5 over low conductivity
> ground; 3 dB beamwidth: 15 degrees either side of boresight.  Each element
> is built with heavy wall Al tubing, starting with 32mm diameter, stepped
> twice, and ending with 19mm at the element tips.  Each of the six,
> 75mm-diameter boom segments measures 9M long.  On-air reports of this
> behemoth vs a wide-spaced 5-el Yagi support the calculated performance
> values.
>      The second article is A Secret Story About the Yagi Antenna, written
> Prof Gentei Sato of Sophia University, Tokyo.  The article recalls his
> to locate Newmann's Note, a set of papers reportedly recovered from a
> burning trash pile after Japan's conquest of the British fortress in
> Singapore in February, 1942.  It was from these notes, written by British
> POW Newmann (variously identified in the article as Private, Corporal or
> Master Sergeant) that Japanese engineers and military staff first learned
> the Allies' effective use of the Yagi antenna in RADAR.  Up until then,
> Yagi-Uda antenna, invented in Japan in 1926, had been used by the Japanese
> in only two radio links to connect two off-shore points to the mainland.
> The author comments that he himself learned during a visit to the
> Smithsonian Institution in DC the the two atomic bombs that devastated two
> of his country's cities included Yagi antennas as part of the
> altimeter/detonation circuit.
>      I found both of these articles to be a fascinating and colorful bit
> background on an invention that we TT'ians almost take for granted - the
> venerable Yagi-Uda antenna.
> 73 de
> Gene Smar  AD3F
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