[TowerTalk] Poor Man's Rhombic

[Tom Rauch]

> Date:          Tue, 28 Apr 1998 07:43:33 -0700 (PDT)

Hi Ward,

> Oh, now this is interesting - so maybe a poor man's rhombic could be made
> from one good-sized support?

That's the idea. I had two at WXEZ FM on 160 meters, with a 350 ft 
high apex.

> Run a slantend wire up from ground level,
> back to ground level, terminate at one end and feed at the other.  Hmmm...
> It might have to be a pretty high support, but Western Wash has some
> pretty sizable Douglas Firs.

These antennas are not the same as the "toys" sold by B&W and others. 
Long wire arrays require actual design work to align the lobes. The 
antenna must have:

1.) proper height to align the main  lobes in phase from 
each leg.

2.) legs more than 1 wl long at the lowest frequency.

The real Inverted V is nothing more than a Rhombic, turned on its 
side. The earth below and around  the antenna forms the missing 
half, at the expense of some additional loss.

> Anybody tried this configuration below 20-meters?

Yep, on 160 and 80. I ran coaxial lines to the far ends, and used a 
phase adjustable combiner to sum the termination end back into the 
feedpoint. This is worth about 2 dB more gain, because the power 
normally dissipated in the termination resistor is added back in at 
the transmitter and contributes to ERP in the desired direction.

Two antennas cover four directions, and work over at least a 2:1 
frequency range with fair to good gain and excellent F/B.
   
Sorry John, the Inverted V is correctly described (at least 
according to textbooks by popular professionals like Kraus, Jasik, 
Balmain, Kuecken, and others) as a half-Rhombic turned vertically. 
The popular Ham Inverted V is really just a droopy dipole that 
incorrectly is called the same  name a vertically polarized 
half-Rhombic has used for many years in commercial circles.

I see nothing wrong with calling it an inverted V dipole, but it sure 
isn't an Inverted V antenna, and it sure isn't that goofy thing Denny 
Had sold to B&W in the early 80's.

73, Tom W8JI
w8ji.tom@MCIONE.com

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