No idea, but if NASA buys something, the mfr sometimes says ¡°as used by NASA¡±.
For all we know, someone bought one for the ham club at one of the centers.
There¡¯s a somewhat famous story about a NASA funded a study to test the lack of efficacy of something (lightning eliminators?) and all the manufacturers of the bogus equipment started advertising ¡°as used by NASA¡±.
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On Feb 29, 2024, at 4:52?PM, N2MS <mstangelo@...> wrote:
?How about the term counterpoise as a return? If the return is a wire or wires we can refer to it as radial(s)?
I recall HF communications was tested on a Project Gemini Flight. I don't remember the details but they used R390A receivers at the ground stations.
I have a report about with the details. If found I will post it.
Since were discussing space and analyzers MFJ mentioned in one of their recent ads that their Antenna Analyzer was used by NASA. Does anyone have any information about this?
Mike N2MS
On 02/29/2024 6:52 PM EST W0LEV <davearea51a@...> wrote:
Jim Lux, I just have a lot of trouble with RF energy and the term
"ground". It's maligned in the amateur circles. There is no need for
"ground" with RF fields, just a return.
Please comment.
Dave - W?LEV
On Thu, Feb 29, 2024 at 7:51?PM Jim Lux <jimlux@...> wrote:
ISS isn't using HF long wires, either. Most of its antennas are things
like patches (which are a sort of end fed dipole) or horns (which have tiny
monopoles in the feed point) possibly illuminating a dish.
There *are* spacecraft that use monopoles for HF and lower (they're
generically called "fields and waves experiments") - for them, the
feedpoint is the junction of the wire/boom with the spacecraft body, so
it's a fairly asymmetrical antenna. Cassini has several booms at
different angles.
And often, because a full size antenna for 1 MHz is quite large (300 meter
wavelength), the antennas are more "voltage probes", with a high Z
amplifier measuring the voltage at the base of the antenna.
On HF sounders (running around 9 MHz) such as MARSIS or REASON (the latter
is on Europa Clipper) it's an actual dipole, although not necessarily
resonant.
On *my* space vehicles (SunRISE mission), there's two crossed dipoles with
2.5 meter booms, feeding a balanced FET input preamplifier.
-----Original Message-----
From: <[email protected]>
Sent: Feb 29, 2024 10:08 AM
To: <[email protected]>
Subject: Re: [nanovna-users] where is the end fed natural resonance
The word counterpoise has no applications in amateur radio, but most times,
it is misused and misapplied. I just checked all my graduate and one
undergrad antenna references. Nowhere is the term "counterpoise" to be
found. Then I checked Wikipedia. The opening verbiage gives the
"standard" understanding, quoted below:
In electronics and radio communication, a *counterpoise* is a network of
suspended horizontal wires or cables (or a metal screen), used as a
substitute for an earth (ground) connection in a radio antenna system. It
is used with radio transmitters or receivers when a normal earth ground
cannot be used because of high soil resistance or when an antenna
is…
Read More
Further, the first reference listed in the Wikipedia article is Cebik.
For decades I have been using the term "image plane" in reference to the
more common (and misused) term "ground plane". I believe in using the term
"counterpoise", we truly are referring to the "image plane". So, Cebik is
correct in discouraging the (mis)use of the term "counterpoise". Indeed,
all my references include treatment of "image theory". Again, none of
these treat or address "counterpoise".
I also point out that the ISS has no mechanism of connecting to "ground"
for a "ground plane". But,.......drum roll........its occupants have
absolutely no trouble bidirectionally communicating with earth via a
number of RF links. Absolutely no "ground" involved.
Dave - WØLEV
