The resistive part of the impedance of the dipole is a function of its
height above ground. The ARRL Antenna Book and Handbook cover this. The
center of your antenna is significantly lower than 1/2 wavelength above
ground and will be less than 73 ohms. I am not sure why you are reading VSWR
= 2.3:1 because I would expect a pure resistance of 29 ohms to give a VSWR =
1.7:1 .Perhaps you have some Broadcast signal adding to the signal being
read by the analyzer.
However, as long as you can feed power from the transmitter into the feed
line it will not make a noticeable difference to the folks you are working.
The antenna tuner or the transceiver antenna (feed line) matching unit will
assure that the power goes into the feed line and off to the center of the
antenna for radiating to the people you wish to work.
Tod, KØTO
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of K6TFZ@aol.com
Sent: Wednesday, February 18, 2004 3:18 PM
To: towertalk@contesting.com
Subject: [TowerTalk] Dipole Problem
I always thought a dipole was simple. First the description:
75 meter dipole (58.5 feet per leg) placed 4 feet above peak of second story
roof. Roof is 40 feet wide so ran extra wire at right angle outward toward
rest of house (big square "U").
Center of dipole is in center of 40 foot section using a large egg insulator
and an SO-239 to start, balun later.
My AEA-HF and Autek RF-1 both read resonance at 3968 KHz which is fine BUT
SWR is about 2.3:1, R=29 ohms.
The only thing I can figure is the way I wrapped the wire on the egg
insulator: so that if
the insulator were to break, the wires would catch each other and not part.
Could there be that much capacitance there to throw my reading off that
much?
The wires are at right angles to each other. Any other suggestions?
TIA. Geoff, K6TFZ
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
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