Red Wave Radio

What antenna is the best AM radio antenna?

Regards,

jdhl

_________________________________________________________

The one that KFI has down in Orange County, CA.

W7TI

Its called the dx sloper and its available at
hro ham radio outlet in anahiem california,atlanta ga,portland ore.hamradio.com
is the web address.

"The one that KFI has down in Orange County, CA. (is the best AM radio
antenna)".

My records show KFI as a non-directional 50-KW station on 640 KHz.

KFI`s antenna is excellent for its frequency and purpose. It would
receive Ames, Akron, Norman, St. John`s, and Cuba, perhaps, on 640 KHz.
It would also do well on the rest of the broadcast frequencies. It
doesn`t have to be resonant. But, hooked to a broadcast receiver in
place of the KFI transmitter, most of the time it would likely hear a
noise jumble on 640 KHz.

A better antenna for a listener is probably a tuned rotatable loop that
can be adjusted for the favored direction and frequency.

Best regards, Richard Harrison, KB5WZI

A high-level modulated r-f power amplifier is a mixer for r-f and audio.
Some r-f received by the transmitting antennas gets mixed in with the
locally produced r-f. The received energy is so much less than the
desired energy being transmitted that it is hardly noticed.

During adjustment of our 790 KHz directional array, we often could hear
KABC in Los Angeles, almost 2000 miles from Houston.

More importantly, we could also hear KTRH, 50-KW, just 20 miles and
50-KHz away at 740-KHz. It not only appeared in our bridge receiver. We
could hear KTRH when we were unmodulated and turned-up the volume on our
monitoring amplifier. It appeared in the noise and distortion on our
measuring equipment but it was always more than 50 db below our fully
modulated level, and that was the maximum allowable.

Those extraneous carriers and noises get modulated at very low levels
and transmitted as carrier noise. The station`s transmitting antennas
are also receiving.

Best regards, Richard Harrison, KB5WZI

<snip>

Quote:>A better antenna for a listener is probably a tuned rotatable loop that
>can be adjusted for the favored direction and frequency.

_________________________________________________________

Depends on how you define "better".  The KFI antenna is a low-angle one due to
the presence of an effective ground plane (I presume; haven't personally
inspected it).  The loop, without a ground plane, is a high-angle antenna and
would probably come in second for serious DXing.  A rotatable loop does have the
advantage of being able to null out interference.  

73, Bill W7TI

"Depends on how you define "better". The KFI antenna is a low-angle one
due to an effective ground plane---."

True. No inspection needed. The FCC requires an efficient antenna
system. It is a vertical radiator with a good ground system.
Broadcasters maximize radiation in a horizontal plane to the extent
allowed by economics and regulations.

For "better" reception, signal strength is not as important as signal to
interference ratio. At least, Ames, Akron, Norman, St. John`s, and a
station in Cuba share the air in and around North America with KFI on
640 KHz. Adjacent channels tend to spill-over into the desired channel
in most receivers.

If you are near one of the stations on 640 KHz or one of its adjacent
channels, it is likely you will only be able to hear the near station
most of the time. At a distance from them, you may be able to pick one
from the pack by positioning your loop antenna. The loop will also
discriminate against man-made and natural interference in its null
directions. KFI`s antenna doesn`t have any null directions.

Best regards, Richard Harrison, KB5WZI

_________________________________________________________

I see why we're not in perfect agreement here.  I think in terms of DXing very
weak, far away signals where signal to noise ratio is most important.  You're
thinking of listening to relatively strong stations where interference is the
main concern.  For my preference, a 5/8 wave vertical with good ground plane is
near-ideal for BC reception.  For yours, the loop is best.

Like I said, it depends on how you define "better".  :-)

73, Bill W7TI

Well, the little Select-A-Tenna broadcast-band AM loop really makes
signals pop out of the noise. The faintest signal will literally jump
out at you with the loop, even when used with a cheap radio.

The main problem is finding dx signals that are relatively in the
clear, and not covered up by local stations.

Bob
k5qwg

Quote:

>Like I said, it depends on how you define "better".  :-)

>73, Bill W7TI

""For my preference, a 5/8 wave vertical with a good ground plane is
near ideal for BC reception."

Reciprocity rules, and many a-m broadcasters would say your choice was
best for them, too.
They would be just about right so long as they needed 360-degrees of
uniform coverage.

An agency I worked for during the cold war operated a European broadcast
monitoring station in Germany. It busily recorded many different
outlets. It studied and used the information so obtained. The listening
post was in a very quiet spot and did the best it could to get clean
reception. Multiple tower arrays were phased to enhance reception and
place nulls in the directions of intefering stations. These could be
quickly readjusted to receive a more fruitful outlet at a different
hour.

The multi-tower array wasn`t the best antenna to receive all outlets.
Loops with huge ferrite cores and some loops with air-cores were also
used. Whatever proved best was used.

I doubt that a non-directional antenna was ever the antenna of choice.
Even with a strong signal and little interference a directional would
have been chosen just for the insurance.

All the h-f reception was done not only with directional antennas, but
with triple diversity as well.

I agree that KFI has a fine non-directional antenna, but for best
reception of distant signals your chances are better with a directional
antenna.

When I lived in Europe, after midnight when most of the Europeans had
signed-off, I used to listen to Edward R. Murrow and the CBS News from
WCBS in New York. If WCBS happened to fade, I just rocked the dial a tad
to WWL which was carrying the same program in New Orleans. I was using a
Beverage antenna with a Hammarlund SP-600. It always gave good results.

The Beverage is a good example of what works. It is inefficient and
gives no where near the strongest signals. But, it surely gives a good
signal to noise ratio because it is quite directional.

Ther problem with KFI`s antenna as a receiving antenna is that it is
very efficient but completely non-directional, except for the null at
its zenith.

You usually have plenty of receiver gain, especially if you are
fortunate enough to have a "Super Pro". In the broadcast band, the
signals are usually competing with atmospheric noise, other external
noise, and unwanted signals, not internal receiver noise. So, I still
contend that the main worry is signal to noise, not feeble signals.

Best regards, Richard Harrison, KB5WZI

I dunno, I saw one at Santa Cruz sitting in the middle of what appeared
to be a big salt marsh that looked pretty good.

Dick

I think I would prefer the loop most of the time for AM-BC listening
just judging from past use on different radios. I like the abilty to to
null stuff out. I got a bonus when I bought a new ic-706 recently. It's
a great AM-BC receiver for its size. And real good audio too. It uses a
fairly wide 8 kc AM filter which I think really helps the audio. Many
ham rigs have too narrow of filters for am use and don't have very good
audio. But I've been using the 706 for this lately with my 160-80-40
combo dipoles, and has been doing real well. It's quickly becoming my
favorite AM radio. It's also real good to SWL the HF bands. Alas, the
longwave is usuable , but nothing to write home about. The lower the
freq, the worse it gets. MK
--
http://web.wt.net/~nm5k

While traveling in Wyoming, I can listen to KFI at night!  That system
works wonders!

Dino

Quote:>The one that KFI has down in Orange County, CA.

>W7TI