[Elecraft] Antennas with resistor and OCFD.

[Fred Townsend]

True rhombics are hard to rotate. Even harder is finding the space to put
one up in the first place. See what your HOA has to say about it.
73
Fred, AE6QL 

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Ron
D'Eau Claire
Sent: Thursday, December 10, 2015 8:43 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Antennas with resistor and OCFD.

Fred, K6DGW wrote:

Ummm ... rhombics *always* work well for their intended use. 
Unterminated, they are bi-directional.  With the terminating resistor, they
are unidirectional in the direction from the feedline to the terminator.
Since terminated rhombics are usually 2 or more wavelengths on a side, they
have very narrow beamwidths with a big F/B ratio, low radiation angle, and
high gain.
------------------------

Quite so but it's worth noting that the unidirectional characteristics
obtained with a terminating resistor did not result in any additional gain.
Instead, the resistor absorbed the RF that would have been radiated on (or
received from) the reciprocal heading, giving the array its unidirectional
characteristic.

Yagi's, quads and similar arrays gain a stronger main lobe by suppressing
radiation in other directions.  

A rhombic is a classic example of how the best design is not always the
design that radiates the most RF. 
The problem with a rhombic for Ham use on the HF bands is that they tend to
be an absolute beast to try to rotate. 

73, Ron AC7AC

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html Message
delivered to fptownsend at earthlink.net