On Fri, 2 Jan 2004 23:58:37 -0600 (CST),
(Richard Harrison) wrote:

Mark Keith wrote:
"For DX transmitting on the lower bands, vertical polarization is the
best way to go."

In some cases. If that were always the case, why do commercial shortwave
stations all use horizontal polarization for both point-to-point service
and broadcasting?

Again this HF advice to an MF enquiry. The two, propagationally are
as different as bananas and apples.

In his book, "Radio Antenna Engineering", Ed Laport says:

"The earliest high-frequency beam antennas used vertical polarization,

This begs the historical perspective that the meaning of High
Frequency has not been constant. Laport's statement belies this era
he quotes who characterized High Frequency as anything above 500 KHz
and often characterized the shortwave frequencies as Ultra High
Frequencies.

The "earliest high frequency antennas" were in fact BCB. And guess
what, they are still Vertical antennas!

but subsequent evolution has caused the almost universal use of
horizontal polarization.

The subsequent evolution is explicitly shortwave. This validates your
experience but says nothing of the problem at hand in the 160M band,
which by example of a few KHz away is dominated by BCB verticals
almost to the point of saturation.



73's
Richard Clark, KB7QHC

Richard Clark wrote:
"The "earliest high frequency antennas" were in fact BCB."

Yes, but not in Ed Laport`s book. Ed`s book covers LF, MF, and HF. Ed as
Chief Engineer of RCA International was most interested in RCA`s
maritime service, radiograms, shortwave broadcast, and radio relay
services. These were conducted above 1700 KHz. Ed observes that HF
propagation is a statistical business, as the ionosphere is always in
flux. Ed gives guidance in using the NBS Central Radio Propagation Lab
publications, hardly the advice of someone stuck in low gear.

Ed gives some of the most complete information to be found on horizontal
rhombics and rhombic arrays, hardly the advice of someone treating the
use of low frequencies.

Richard Clark wrote: "And guess what, they (earliest high frequency
antennas) are still Vertical antennas.

I agree that 1.7 MHz is medium wave as the break is often chosen as
3MHz. I also agree that MW broadcasting antennas are universally
vertically polarized.

The primary service area of a MW broadcast station is defined by the FCC
as the area well served by the ground wave. Of course vertical polarized
antennas are used because horizontal polarization produces no ground
wave.

Art Unwin started this thread it seems because he faulted a vertical
antenna for not having a 100-mile range using low power.

The vertical has a null overhead almost guaranteeing no short-hop sky
wave.
Low power obviates ground wave DX.

To make an evening sky wave trip of 100 miles at 160 meters, Art needs
an antenna with a lot of high-angle radiation, 60 or 70-degrees more or
less to use the ionosphere for short skip, or he needs enough effective
power to punch a signal through along the ground.

A horizontal dipole could provide the high-angle radiation for the sky
wave.

A vertical antenna could provide the ground wave signal which only needs
enough power to work day or night.

A 1/4-wave vertical antenna can produce an unattenuated field strength
at the earth`s surface of about 195 mV/m at one mile. At 100 miles, the
field strength is 1%, or about 2 mV/m.. Depending on the soil
conductivity, the actual signal reaching a receiver at 100 miles is
likely much less than the unattenuated value. In a quiet location, not
much signal is needed.

Best regards, Richard Harrison, KB5WZI

On Sat, 3 Jan 2004 15:51:33 -0600 (CST),
(Richard Harrison) wrote:

Richard Clark wrote:
"The "earliest high frequency antennas" were in fact BCB."

Yes, but not in Ed Laport`s book. Ed`s book covers LF, MF, and HF. Ed as
Chief Engineer of RCA International was most interested in RCA`s
maritime service, radiograms, shortwave broadcast, and radio relay
services. These were conducted above 1700 KHz.

However, his observation was a historical one, not a current (at the
time of printing) one as evidenced by his stating that things changed.

snip
Art Unwin started this thread it seems because he faulted a vertical
antenna for not having a 100-mile range using low power.

The vertical has a null overhead almost guaranteeing no short-hop sky
wave.
Low power obviates ground wave DX.

This is far from true and again relies on HF, not MF observations.
You don't have to go very deep into your buddy's "Radio Propagation
Handbook" (Pete Saveskie). Chapter one, Ground Waves, employs a very
simple scenario with an 1/8th wave vertical radiator monitored out a
distance of 240 KM to no apparent difficulty in Ham terms, much less
FCC coverage issues. The discussion of the necessity for horizontal
antennas at this greater distance is notable by its vacuum in the
text.

My own study of Ground properties through a variety of references has
found there is quite a characteristic shift, a knee in the data, at
the 3 MHz frequency that clearly differentiates propagation at 160M
from that of 80M.

Shortwave stations clearly have an economic necessity to optimize
within their bands of operation. BCB stations are likewise
constrained. The two exhibit very different antenna solutions. It
follows that 160M more closely conforms to BCB than Shortwave for all
reasons considered.

To make an evening sky wave trip of 100 miles at 160 meters, Art needs
an antenna with a lot of high-angle radiation, 60 or 70-degrees more or
less to use the ionosphere for short skip, or he needs enough effective
power to punch a signal through along the ground.

A horizontal dipole could provide the high-angle radiation for the sky
wave.

And yet experience and reporting to this matter has shown abysmal
results. The shortfall of expectation with regard to actuality lies
in the Ground.

73's
Richard Clark, KB7QHC