Stephanie,
I have been on travel and just read your posting.
My guess is that they are thinking in terms of tactical communications.
Humvees, tanks, personnel carriers, and the like use whip antennas for most
HF and low-range VHF communications. Those are vertical, of course. Yes,
I have seen dipoles, inverted-Vs, and log periodics - all horizontal - at
various military installations in a fixed location. Someone commented that
they can envision a "cleared" area (or zone) of NO BPL around military
bases and installations so that they will not have to suffer from this
stuff as most hams will. There may be some truth to that scenario, given
the wishy-washy nature of the NTIA main text filing. However, since they
will not have control over the local RF environment with moving convoys and
units deployed in the field, the vertical component of the BPL signal
becomes a significant concern for the mobile units.
My own take on NTIA's overall response is that it seems to be a disconnect.
The front end says to the FCC "Go ahead and do this, but sorta think of
us", while the attachment makes a lot of the same case that is being made
for Amateur Radio. My personal feeling is that the first part of their
comments is very weak and poorly stated, which is unfortunate and does not
help the cause against spectrum pollution. If NTIA is able to carry out
their tests as indicated below, the results should be of interest to hams
who operate mobile and those using vertical antennas at home. It would be
nice if NTIA would re-think the tests and run both polarities for all
tests.
73, Dale
WA9ENA
"Stephanie WX3K"
<wx3k@ptd.net> To: <rfi@contesting.com>
Sent by: cc:
rfi-bounces@conte Subject: [RFI] NTIA BPL
measurement procedures
sting.com
08/19/2003 04:33
PM
http://www.ntia.doc.gov/ntiahome/fccfilings/2003/bplcomments_08132003.htm
How did they arrive at the conclusion that most receiving antenna systems
are vertically polarized in the 1.7 - 80 MHz region ? Would anyone like to
share their take on this ? Im mostly curious and at the same time somewhat
skeptical
4. Measurement Procedure
Ensure that the antenna's main beam has an unobstructed view of
the BPL source. Photograph the antenna's view of the BPL source. Transmit
the same, repeatable test signals over the network for each signal
measurement. At the first location, examine the BPL signal envelope to
confirm or discover the repetition interval. Record the envelope over one
period. Start the peak value measurement system. Start the average value
measurement system to run concurrently with the peak value system. Upon
completion, switch to the quasi-peak system and perform a stepped
measurement. When the measurement system finishes, turn off the BPL
signal.
Run the three measurements again.
Proceed to the next location and repeat the measurements in the
above paragraph. Generally speaking, most receiving antennas of concern in
the 1.7 ? 80 MHz spectrum are vertically polarized so these polarizations
will be used. In a few locations, average power measurements will be made
using both polarizations, noting that horizontally polarized receiver
antennas are also used and propagation effects may depolarize the BPL
signals.
Stephanie R. Koles WX3K
wx3k at arrl dot net
http://www.qsl.net/wx3k
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