What??? Four 1/2 wavelength wires!! You gotta be kidding!!!

The Rhombic at AGA5HI in the early 70s was close to 6 wavelengths per side.

There are/were two different rhombic designs. [Roy may want to comment
on this.] A resonant rhombic without a termination resistor is
bidirectional. A non resonant rhombic, a traveling wave design that uses
a terminating resistor is unidirectional.

Gain increases as the length of each side increases. Directivity [gain]
is also dependent on the included angle which contributes to radiated
beam width.

AK

Reg Edwards wrote:
"Cecil Moore" wrote

Reg Edwards wrote:

A terminated rhombic is only 50 percent (or even less) efficient.

But it's 50% in the bad direction, not the good direction. :-)

===========================================

In the most simplistic of terms, a rhombic consists of four
1/2-wavelength wires plus a lossy resistor which gets hot.

If the four 1/2-wavelength wires are rearranged to form a dipole, plus
a reflector, plus two directors, we have only one good direction in
which 100% of the power is radiated. Nothing gets hot.

Common sense prevails. No need to refer to Eznec. Even a drunken
old-wife would know which arrangement to choose, if only because it
saves the cost and fitting of a high power, non-reactive resistor.
;o)

But no doubt US Army Field Manuals still call upon rhombics.
----
Reg.