Users may not create topics, posts, or private messages containing or relating to the following material (especially pertaining to Motorola copyrighted software, unless you want Motorola to come along and shut this site down):

  • Listing for sale or trade of, or links to sites offering for sale or trade of, or giving away, Radio
    Service Software (RSS) or Customer Programming Software (CPS)
  • Profanity, pornography, defamation, or slanderous remarks directed towards any individual or entity
  • Commercial advertising (except in the Batboard Vendors forum, as approved by the Admin/Mod Staff)
  • Any other items which may be deemed as offensive

If any topics, posts, or private messages containing or relating to the aforementioned material are brought to the attention of the Admin/Mod Staff, they will be deleted.

Additional FAQ items appear here in Forum Rules. Please review them for posting guidelines and further clarification.

Achieving 360° Coverage On Side Mount Antennas

This forum is for discussions regarding System Infrastructure and Related Equipment. This includes but is not limited to repeaters, base stations, consoles, voters, Voice over IP, system design and implementation, and other related topics.

Moderator: Queue Moderator

Birken Vogt
Posts: 262
Joined: Thu Nov 10, 2005 7:53 pm

Achieving 360° Coverage On Side Mount Antennas

Postby Birken Vogt » Thu Oct 27, 2016 6:58 am

We recently noticed a lack of tx coverage on the back side of a large lattice tower.

The tower is a 3 sided tubular steel tower about 5 feet on a side where we are about 100' up.

Our customer has a DB222 antenna stood off about 4' from the tower.

I am wondering if the narrowness of the entire antenna package makes it more susceptible to blocking by the tower.

Would an antenna of this type: http://www.sinclairtechnologies.com/cat ... px?id=1435 get across to the back side any better, or is there any experience with this sort of thing?

I have also considered a transmission line splitter to get an antenna on the other side like a water tank would, but I foresee phasing issues and nulls and the like.

Thanks.

Karl NVW
Posts: 129
Joined: Wed Sep 03, 2003 7:13 am

Re: Achieving 360° Coverage On Side Mount Antennas

Postby Karl NVW » Thu Apr 19, 2018 3:17 pm

You will always have reflections and attenuation when the tower is larger in width than 1/4 wavelength.
So put the antenna on the side where you need to talkfurthest, then hope for the best, OR
Buiild a new 100 ft tower so that the DB222 antenna can mount at the top without being shadowed by the tower structure in any direction.
Karl - WA8NVW AFA5VB
SHARES + NCS

Jim202
Posts: 3565
Joined: Sun Sep 09, 2001 4:00 pm

Re: Achieving 360° Coverage On Side Mount Antennas

Postby Jim202 » Sat Apr 21, 2018 12:22 pm

You could install a power divider to split the power into 2 equal values. The coax cable that will be needed to feed both antennas has to be cut to close tolerance to match the frequency of use and be exactly the same lengths for both cables.

Mount one antenna off the point of one tower leg and mount the second antenna off the middle of the face on the opposite side of the tower. The tower leg mount will be no problem, but the center face of the other side of the tower will take some skilled design work to get a mount to work. The distance off the tower structure comes into play here and needs to also be calculated.

I would suggest getting the antenna company involved with helping you work through this problem. If one side of the tower needs to cover a greater distance than the other, let the antenna company know this up front before you get very far into this project. You want to do this only one time and not come back to fix a screw up that should have been covered from day one.

This project is not one the average radio tech should take on by them selves. Good luck on your efforts and do let the group on here know how you make out.


Return to “Base Stations, Repeaters, General Infrastructure”

Who is online

Users browsing this forum: No registered users and 1 guest