On Dec 6, 2005, at 8:27 PM, [EMAIL PROTECTED] wrote:
Would you (or anyone) please elaborate on the use of an Rx antenna?
The fundamental problem on the low bands is the high noise level. A
good transmitting antenna can often have S6-9 noise, or worse. It's
hard to hear weak signals with all that noise.
As W8JI would put it, the characteristics of a good transmitting
antenna and a good receiving antenna aren't the same. A transmitting
antenna should have gain in a particular direction (and angle) in
order to place the most signal into the target area. For receive, at
least until you get into the upper VHF region, gain isn't really
important. The problem is noise -- you can pick up the ambient noise
on the band with barely any antenna at all -- all that gain just
brings more noise into the radio.
For receive, the important thing isn't gain, but antenna pattern. An
antenna with a good pattern will ignore noise (and QRM) from
directions outside the target area. Less noise means better signal to
noise ratio. Signals that aren't audible on the transmitting antenna
are then audible on the receiving antenna.
There are many designs for effective low-band receiving antennas.
These are quite lossy, having gain 20-30 dB below that of a
transmitting antenna. Examples include Beverage antennas, Flags,
Pennants, EWEs, K9AY loops. Despite being lossy, they can have quite
sharp patterns, especially the Beverage antenna.
Bill Coleman, AA4LR, PP-ASEL Mail: [EMAIL PROTECTED]
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
