I wrote:
"Two endfire Pennants will narrow the cardioid pattern only slightly.
The TOA will also lower slightly and, of course, there will be about 3 dB
gain over a single Pennant. There is really little advantage for the
endfire Pennant configuration."
==========
>From the recent posts on this subject, I get the impression that my
comment about 3 dB gain was taken as "WOW!".
The name of the game in improving reception on 160m is signal-to-noise
ratio, not gain! If you have a phasing device such as the MFJ-1025/1026,
connecting two Pennants to them to move the null around might be one way
to improve the S/N as compared to a single Pennant. But because Pennants
are themselves directional, I feel it would be better to use a pair of
non-directional antennas with such a phasing unit.
Jeff's (K8ND) original question was whether a pair of Pennants could be
used in a staggered configuration while the Pennants are oriented for
best reception in the desired direction.. Upon modeling such a
configuration, it was seen that the pattern is quite lop-sided no matter
what the phasing. The phasing with the best looking lop-sided pattern
(best null) when the Pennants are staggered with one of them 150' to the
side and 150' to the rear was with the current in the front Pennant
lagging the current in the rear Pennant by 60 degrees.
As Tom (W8JI) correctly pointed out in his post on the subject, if two
endfire Pennants are fed 180 degrees out of phase, additional deep nulls
directly off of the sides are obtained, as well as the deep null to the
rear. The resulting narrower forward lobe definitely shouts out that the
S/N ratio is better than if the same two endfire Pennants spaced 1/4-wave
were fed only 90 degrees out of phase.
73, de Earl, K6SE
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|