Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Multiple Mobile Antennas  (Read 359 times)
KB9YZL
Member

Posts: 16




Ignore
« on: April 23, 2003, 01:09:57 PM »

I currently work for the Meteorology Department of the local Community College as their "Radio Guy". (A position I fell into, due to my knowing just enough about radio gear to be a danger to myself.)

Over the past ten years, our mobile electronics have gone from a single CB, to the 11 antenna setup currently being worn by our lead van.  This setup includes two 2M sets, two CBs, three scanners, one TV, one GPS, and two cell phone antennas.  Aside from looking like a porcupine, everything seems to be functional, but I am concerned about interaction between the various sticks up there.

I have noticed significant changes in SWR when an antenna is evaluated individually, and then checked again as part of the whole setup.  It's not bad enough to keep me from keying up, but it's troubling to see an antenna go from 1.2:1 when measured alone, to 1.7:1 when it's part of the group.

I am not an electronics wizard, (obvious, isn't it?) so I'd like to hear some other opinions on the subject.  Thanks in advance!

Kent
KB9YZL
Logged
K5LXP
Member

Posts: 4507


WWW

Ignore
« Reply #1 on: April 23, 2003, 03:24:10 PM »

First off, the SWR differences you're seeing aren't significant enough to worry about.  You *could* optimize each one for *absolute* performance in the environment it's installed in, but I doubt you'd see a measurable difference when you're done.  I've got 8 antennas on my truck, I find the interaction minimal.  Surely I overload the front end on some radios while transmitting on one band or another, but receiving on other bands while transmitting isn't a requirement in my case.  If you want to improve the isolation between some radios, look into getting a combination of diplexers and triplexers, available from the likes of Comet and Diamond.  The port-to-port isolation on these is pretty good, and might give you antenna/radio options you haven't thought of yet.

Mark K5LXP
Albuquerque, NM
k5lxp@arrl.net
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!