The 1/2 wave antenna has been some what of an enigma to a lot of people over
the years. I used one for years and still use one today. I work mostly the
"Low bands" (160-30) and never wanted the bother of keeping up an HF beam up
a tower! I DID go thru an extreme VHF/UHF stage when I was on 144/432 Mhz.
and contemplating some 1296 operation though. The activity down here fell
way off and I finally sold all the goodies as they became useless when the
trend towards VHF/UHF fell apart when nearly all the old timers went SK. No
use being able to run 500 watts PEP on 2 SSB when there ain't anybody to
talk to more often!
The end fed Zepp or just a "plain" end fed 1/2 wave can be big trouble when
you run a lot of power as there is inevitably the "RF in the shack" syndrome
forcing changing antenna lengths to compensate for the problem. I am
presently using a 115 end fed which is ideal for 80-30 including the 60
meter band. You can get by with a poor ground system and still radiate a
pretty decent signal with just something like a very simple "L" section
network to match it to your rig. Ground losses are much less with little or
no effect from adding counterpoise wires/grounds to suppress mostly "RF in
the shack" troubles, which are minimal on QRP and 100 watts or less.
Lots of people look upon the half wave with distain, but it can do a
remarkable job, especially in neighborhoods where beams and "visible"
antennas are frowned upon by Home Owners Associations and the attendant
"trolls" looking for "errant amateurs" to torment. The 115 wire I now have
up was used out of a hasty attempt (successful!) to get back on the air when
my XYL had a stroke which didn't mix well with my outdoor "ham shack" in the
carport building! I regularly work CW with it with 100 watts or less from
80-20 meters and also SSB in the afternoons on 40 and nights on 75 meters
with the "big boys". I'm using #26 stranded "mil spec" hookup wire for the
radiator and it works VERY well for what it is and the House wiring ground
buss for a "counterpoise"!
Don't sell the antenna short, it can and will work very well if the right
length and with a decent antenna tuner.
73 to all,
Sandy W5TVW
-----Original Message-----
From: Fred Jensen
Sent: Tuesday, October 01, 2013 5:42 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Random wires
Isn't this why AM broadcast stations, particularly 50KW clear-channel
stations, employ base-fed half-wave verticals? They still use radial
fields too I think. I recall [from years ago] that KFI's TX [650KHz]
was in Buena Park CA and the tower was around 700ft tall. BW of a stick
like that is pretty narrow, uncompensated, less than the BW of the signal.
When I saw the original post, I knew it would stimulate a reply-storm. :-)
73,
Fred K6DGW
- Northern California Contest Club
- CU in the 2013 Cal QSO Party 5-6 Oct 2013
- www.cqp.org
On 10/1/2013 2:43 PM, Ron D'Eau Claire wrote:
I disagree. Barry has it right. The radiation resistance of the radiator
is
independent up the ground resistance. That's why a 1/2 end fed wire with
it's very high resistance is highly efficient against a given ground
system
compared to a 1/4 wave long or less wire.
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