Rich, K2CPE wrote:
"My first contact with mine (large horizontal loop) was on 20 m to
Tierra del Fuego at the southern tip of Argentina (5 watts ssb, got a
5x5 sig report!)."

That`s great performance. It helps that Tierra del Fuego is cold and
quiet. I made 2 triops there and spent a total of more than a year there
on the Argentine side of the island about 40 years ago.

I was able to listen to a Houston MW 740 KHz station during Hurricane
Carla on my little Hitachi transistor radio which was about the size of
a package of cigarettes. This does not mean that Rich`s 20m contact
wasn`t special. Ionospheric conditions were probably much different on
separate occations so widely separated in time. Dan Rather came in loud
and clear on 740 KHz from about 1/3 the distance around the globe. I was
very interested in what the hurricane was doing in my absence.

The MUF was pretty high when I was in Tierra del Fuego because when I
connected a 5W Motorola 33 MHz FM walkie talkie to a vertical dipole at
about 20 ft I raised a Midland, Texas oilfield supply company.

I put up a rhombic on the island to communicate with an Argentine public
correspondence station which operated between 80 m and 40 m near Buenos
Aires. The post office in Rio Grande on the Island had a BC-610 that
they used to contact that station, Radio Pacheco, near Buenos Aires. Our
transmitter was a Hallicrafters HT-20, surplus from our Bolivian
oilfield operations. It had been replaced with a Collins 30K-5. We
needed our own radio contact with Buenos Aires because the post office
on the island closed during the frequent postal worker strikes.

When we gave Radio Pacheco a call and told them we were calling from
Tierra del Fuego, they were incredulous. The rhombic was really rattling
their cans.

The only ham active at the time on Tierra del Fuego was Padre Munoz who
presided over the local mission. He tried to use equipment in nearly all
cases identical with ours to assure a source of replacements for
anything that failed. We had Land Rovers. Padre Munoz got a Land Rover
for himself. Same with radios, etc. He was a wise old guy.

My assistant was a nuclear physicist but there was no work for his
specialty at the time in Argentina. So he accepted a job in the oil
patch working with electronics. He was a ham after all and had an
excellent scientific preparation. His name was Alex Eusler. Don`t know
where he is now or what he is doing. Hope he is doing great things with
atoms.

If Bill happened to contact someone on Tierra del Fuego who was using
something like the rhombic erected there 40 years ago, he might expect
good communications. Its gain at 20m is likely 15 or 20 dBd in the
direction of the USA. Even a dipole isn`t bad as evidenced by my
Midland, Texas contact. I was probably right at the MUF at the time, and
Bill was probably well below the MUF on 20m at the time he made his
contact with Tierra del Fuego. His contact was probably much harder to
make and keep working if he were far below the MUF at the time.

Best regards, Richard Harrison, KB5WZI

Mark Keith wrote:
"As far as noise, if the dipole and loop are both horizontal, there
should be little if any difference in noise received, unless the pattern
of the particular antenna favors the noise source."

I wrote that the loop was small at lower frequenciues such as those used
with power mains and BC band transmitters. This can be equalized by an
r-f choke across the receiver input to short out the low-frequency
interference. A folded dipole or loop antenna doesn`t need a choke.
Their configurations provide a short at low frequencies.

I noticed the hum pickup of car radios using untuned r-f anmplifiers
back in the 1940`s. They had no low-frequency, low-impedance path for
noise intercepted by the conventional whip antenna. Radios with a
conventional antenna coil had bo antenna hum problem.

Best regards, Richard Harrison, KB5WZI