Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old July 23rd 07, 07:08 PM posted to rec.radio.amateur.antenna,alt.tv.tech.hdtv
external usenet poster
 
First recorded activity by RadioBanter: Apr 2007
Posts: 20
Default Antenna combiner/joiner question

On Jul 23, 10:42 am, "Smarty" wrote:
Since both antennas cover UHF, point in opposite directions, and are spaced
within a fraction of a wavelength at UHF frequencies and below, it is
extremely likely that the phase cancellations of the two antennas causes the
drop in signal strength when mixed in a combiner. The solutions are far as I
can tell would be to bring both feed lines (coax lines) down to the receiver
and switch when you need one or the other, or to filter out UHF content from
the log periodic with a step low pass filter, or separate the 2 antennas
more, since you appear to be creating a phased array even though you never
intended to by the way you are configuring them. Phased arrays deliberately
add and subtract RF energy to gain directivity at the expense of attenuation
in other directions.

Smarty


Thanks for the quick reply. Right now the best alternative is the
spacing as I only have one downfeed that uses a preamp. What would be
the minimum distance between the two antennas that I should use, or is
it better to stack these instead, and if so what would be the minimum
distance that should be used? Or, would a metal barrier between the
two fix this issue with spacing??

I really appreciate the help.
--
Chris

Reply
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
What is a duplexer, diplexer and combiner? crb Antenna 4 December 8th 05 04:11 PM
wilkinson power combiner James Bond Homebrew 3 November 25th 04 03:39 AM
WANT: Radiomaster AC-108 antenna combiner phoneguy99 Swap 0 August 16th 04 05:10 AM
toroid combiner? outbander CB 5 September 24th 03 02:53 AM
Active antenna combiner (transmit & receive), 30-87 MHz Stefan Moscibroda Antenna 0 August 24th 03 08:52 PM


All times are GMT +1. The time now is 04:54 PM.

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