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Re: [TowerTalk] Effective of ground snow on Antenna radiationpattern

To: <>, <>,"Jim Lux" <>
Subject: Re: [TowerTalk] Effective of ground snow on Antenna radiationpattern
From: "Mike Harris" <>
Date: Sun, 14 Jan 2007 10:32:37 -0300
List-post: <>

| I don't know much about snow properties at HF, but at Ku-band (13.402
| GHz, to be specific), the dielectric properties change a great deal
| with temperature and moisture content.  Ice is not particularly lossy
| or conductive.  Water is very much so.

During the my time in the Antarctic 1974 through 1976 I observed some ice 
depth radar work.  This involved flying for hours at 50 feet above the 
snow surface, determined by radar altimeter and probing the rock bottom 
with 70MHz pulses, transmitted and received by dipole antennas mounted 
under the wings of a DHC Twin Otter.  The only time I've flown with 
reverse pitch to maintain a high sink rate without exceeding the max 
forward speed determined by the experiment.

As far as I am aware snow and ice is transparent to HF.  It is known that 
one base on the Antarctic mainland had a rhombic that slowly vanished 
under the snow surface without ill effect apart from being eventually 
damaged by differential ice movement.  I once laid out a "V" on the 
surface near our snow ski-way which was on about 600 feet thick snow/ice. 
It seemed to work OK but I didn't hang around too long.  The VFO knob of 
the FT-101 I was using was most difficult to turn and the inverter 
transistors of the DC PSU were so cold they didn't want to start up until 
after a few ON/OFF cycles.


Mike VP8NO


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