LinkBack Thread Tools Search this Thread Display Modes
Prev Previous Post   Next Post Next
  #18   Report Post  
Old May 15th 06, 03:26 PM posted to rec.radio.amateur.antenna
Cecil Moore
 
Posts: n/a
Default 100 Ohm Twin Lead

Buck wrote:
Is this a single band or multiband antenna? If I recall correctly,
you can use a different impedance feedline if it is a multiple of a
half wave. At the half wave points, the impedance is the same as the
beginning of the feed.


i.e. at the antenna. You're right, neglecting losses, the antenna
impedance is repeated every half wavelength. Neglecting losses,
that 100 ohm antenna feedpoint impedance will be repeated at half-
wavelength intervals for *any* feedline Z0, including 50 ohm coax.

Cecil or others here will correct the length error if I am incorrect.
But I learned about a year ago that the impedance can be corrected by
the multi-fraction length feedline of a different impedance.

Maybe this is the principal of Cecil's feedline matching system.


The principal of the feedline matching system that I use is that
every SWR circle crosses the purely low resistive point at a
current maximum point. For dipoles that are 1/2WL on the lowest
frequency of operation, the current maximum point is the ideal
point at which to feed the antenna system. Adjust the length of
the feedline until the current maximum point is at the transmitter
and you will usually not need a tuner at all.
--
73, Cecil http://www.qsl.net/w5dxp
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Using Twin Lead or Ladder Line for your Antenna's Feed-in-Line ? - Then 'consider' a Pair of Vintage Style TV Antenna Clips . . . RHF Shortwave 11 December 29th 05 04:05 AM
ABOUT - The "T" & Windom Antenna plus Twin Lead Folded Dipole Antenna RHF Shortwave 0 November 4th 05 06:13 PM
ABOUT - Making a SWL Antenna out of 300 Ohm Twin Lead and TV Coax Cable RHF Shortwave 0 October 28th 05 12:22 PM
using 450 ohm twin lead to feed 43 ft multiband groundmounted vertical Denton Antenna 0 October 3rd 05 01:08 AM
Ground plane vertical fed with twin lead? denton Antenna 4 April 6th 05 05:58 PM


All times are GMT +1. The time now is 12:59 AM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017