My Tecsun PL-380 has one of those
numerical readouts that is the same
as the PL-310. I can't make any sense
out of it but that's just me.
I forgot. I actually did take a vintage pocket
radio frome the 1960s and walked around several
blocks. Again the blocks are small and so are the
lots but the radio got my station 2 or 3 blocks back.
I know the powerlines act as reradiators/coupled
receiving antennas - they do make a difference.
I think that's why when I walked through a
street intersection there was a null. The crossing
lines were phasing each other out somehow. (????)
It wasn't until I got a bunch of radials down that
I could go down to the park 0.7 miles away and
go in the middle where the where no lines - well -
then I could get the station. On a Grundig S-350
(Again a sensitive radio) it was about 80 percent
signal 20 percent noise. If you turned down the
treble control it sounded quite good. My station
was on for a big picnic gathering, and the group
paid some attention to the broadcast - it was
easy to listen to. I probably had more listeners
that day than any other time. (Ha Ha.)
I think it really is amazing considering the incredibly
low efficiency of the transmitting set-up. If you have
an AMT-5000 (class E -I don't) that 90 mW out hits the coil
and then - kablooey - the RF goes into something that
is - what? 0.05 percent efficient? You guys know the
answer, what was it again? - - - .045 milliwatts - -
is that what you get out of the system in the end???
Heck - if that's so I think the kind of range we are
getting is absolutely fantastic.
As Carl has said - it's the sport of the thing to try
to make it better. And many of us are trying to
do that. Are my figures correct? I know there
are tons of variables. Also, according the ground
conductivity map - the conductivity here in CT is
not very good.
Bruce
As a way to get to sleep within 5-seconds I try to visualize strange conductivities in the universe.
Starting with earth, what would ground conductivity be like in the Antarctic where the "ground" is miles of ice?
I have once before asked what a virtual ground would look like up in a space station orbit, and I recall that Radio8Z knew the answer.
We hear of someday colonizing Mars... what will conductivity be like there? I assume they have the same electromagnetic spectrum as we have down here on home planet.
Why does the brain become more creative while taking a shower? Is it because we're grounded through the water and pipes?
Join the ALPB and get even more.
Virtual= In effect though not in fact.
Balanced antennas such as center-fed dipoles do not need or use a "ground," whether real or virtual. They work perfectly in free space, inherently.
Out in space it would be no problem making a balanced dipole for long or medium wave, with the space-station/transmitter in the middle.
But verticle long or medium wave balanced dipole on the surface of the planet would be difficult...
One way you'd need a long transmission line that reached the center;
The other way you could have a transmitter room up in the center of the dipole tower, with maybe an elevator or spiral staircase.
The elevator or staircase would best be non-conductive.
The transmitter cage could double as an NSA spy platform.
Mr. Blare wrote: Out in space it would be no problem making a balanced dipole for long or medium wave, with the space-station/transmitter in the middle. etc
With a bit of research, probably Mr. Blare could/should have realized that the radio frequencies used for telemetry paths to & from space satellites do not use the long-wave or medium-wave bands.
Space satellites use bands whose balanced, self-resonant radiators (not needing either a real or virtual ground) occupy less physical area than the palm of one's hand.
The transmitters and receivers for those bands using such satellite antennas are located on the satellite itself.
Therefore, no need exists for long transmission lines or long, non-conductive ladders/spiral staircases, however humorous that is to contemplate.
Actually, Rich, I am not fully aware of frequencies employed in space, but come to think of it I would expect that long and medium wave would have trouble transversing the ionosphere.
Mars would be a whole other matter.
how about putting a FM (88-108 mhz) broadcast station in space? at say maybe 100 watts continuous duty and uplink to it via one of the GHZ bands
If one were to do that, set up an FM station from a space station, they would rule.