Thread: Query..
View Single Post
  #21   Report Post  
Old January 10th 06, 01:57 AM posted to rec.radio.amateur.antenna
Reg Edwards
 
Posts: n/a
Default Query..


"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.