In a message dated 97-01-21 20:01:24 EST, N0AX writes:
<< I think some of the odd signal strength behavior is due to multiple paths
open at once, maybe close to each other in azimuth. Since the paths are
so long, their signal strengths vary considerably, over many different
time periods. This would cause a variety of interference-related changes
at the receiver. Omnidirectional antennas, by summing all paths instead
of just a few, may act as "diversity" antennas, with better overall
receive levels. >>
Absolutely not. Omnidirectional antenna will never bring more signal than
directional antenna, unless angle of arrival (mostly vertical) is vastly
different. We are dealing here with DUCTING as VE3BMV discovered and
described in CQ Magazine and Radiosporting Magazine.
In the nutshell: we are predominantly not bouncing the signals from
ionosphere (as propagated in the "propagation" books), but ducting and
refracting in the layers, and at much lower altitudes. This explains some of
the crooked path propagation. Nothing unusual. I have seen JAs coming through
90 deg S of the "normal" path, same with Eu signals, coming in at 90 deg more
S than direct path. This is observable on all bands from 10m down to 160.
Vertical angles, I found, can be at the times 70% different on receive vs.
transmit. So what is best on transmit at the time, is not always best on
receive. Vertical angles are at the times more discriminating than most
people know. If you have more antennas for one band and play with them and
observe differences TX vs. RX, you know what I mean (antennas typicaly have
more pronounced nulls in the vertical pattern than in horizontal). On 80 and
especially on 160, you could see differences within hours. One antenna that
is superior now could be useless few hours or next day later. That's why
vertical (and array) or transmit antenna, or even low Inv. Vee, can be at the
times better than Beverage. You will never have enough antennas! Read the
VE3BMV article, build your antennas to fit the propagation modes, and you
will be amazed.
I just scratched the surface and I am entering the second phase of building
new generation of antennas that will take advantage of various propagation
modes.
First though, have to find that elusive mother of all locations (hill vs.
ocean?). This coming weekend I will be checking out one of the ocean
locations. I would appreciate observations and reports especially comparing
to other NJ, MD, DE, EPA stations.
Just example: when operating from CG1ZZ, Jack VE1ZZ put up "new" Beverage
going about 20 deg (which is way too N for Eu for him). Second night in CQ WW
CW this thing was outdoing all of his 9 beverages and foursquare for Eu. I
"could hear" filaments in PA's of Eu stations, it was so quiet and
sensitive.Others had 25 dB more noise on them. First time in my life I worked
more Eu (456) stns than US (403) on 160.
Hope this helps to forget the "bouncing" nonsense and sheds some light on
what is going on. Thank you for the bandwidth and hope CU in CQ 160. Hope
that winds are merciful to my baloons. (Lost one in Stew Perry at 3:00 am and
had to QRT)
Yuri K3BU, VE3BMV
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