ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1] 2 3 4   Go Down

Author Topic: Large RF coverage area, multiple antenna's  (Read 2621 times)

peter dakin

  • Full Member
  • ***
  • Offline Offline
  • Posts: 152
Large RF coverage area, multiple antenna's
« on: December 20, 2013, 05:32:36 am »

What would the best way to combine 4 antennas into one distro, in order to provide coverage for an extremely wide area.
In the past i've used PW Helicals directed at almost 180∘ to each other to ensure mics are being covered by at least one antenna, however I lose any form of diversity, for mics at the far reaches.

Next time around I'd really want to add more helicals, in order to provide mics with true diversity, however the SHURE UA221 splitter/combiners seem a little "delicate" for the job.

Any recommendations would be apreciated.
Logged

Jerome Malsack

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 449
Re: Large RF coverage area, multiple antenna's
« Reply #1 on: December 20, 2013, 09:22:34 am »

Logged

john sanders

  • Full Member
  • ***
  • Offline Offline
  • Posts: 190
  • Eastern Long Island, N.Y.
    • Sonimax Light & Sound
Re: Large RF coverage area, multiple antenna's
« Reply #2 on: December 20, 2013, 09:54:33 am »

Shure Applications Dept. would be a great resource for you. Try giving them a call.
Logged

Brian Jojade

  • Full Member
  • ***
  • Offline Offline
  • Posts: 233
    • HappyMac Digital Electronics
Re: Large RF coverage area, multiple antenna's
« Reply #3 on: December 20, 2013, 10:08:00 am »

How big of an area are you actually trying to cover?

Adding more antennas will likely create more trouble than good for you, as the signal coming to each antenna will interfere with the other by just raw combining them. 

An alternative would be placing additional receivers tuned to the same frequency to cover each specific area, and then activating the receiver on the mixer closest to the mic user.
Logged
Brian Jojade

Mac Kerr

  • Old enough to know better
  • Administrator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3168
  • Audio Plumber
Re: Large RF coverage area, multiple antenna's
« Reply #4 on: December 20, 2013, 12:16:30 pm »

What would the best way to combine 4 antennas into one distro, in order to provide coverage for an extremely wide area.
In the past i've used PW Helicals directed at almost 180∘ to each other to ensure mics are being covered by at least one antenna, however I lose any form of diversity, for mics at the far reaches.

Next time around I'd really want to add more helicals, in order to provide mics with true diversity, however the SHURE UA221 splitter/combiners seem a little "delicate" for the job.

Any recommendations would be apreciated.

When using multiple antennas to cover different zones you have to be very careful to be sure there is essentially no overlap in coverage. You have to take the antenna coverage patterns, terrain, structures, etc into consideration to eliminate covering the same area with 2 antennas on the same side of your diversity system. If you have overlapping coverage you have created an area where you are going to have multipath reception, which can cause dropouts rather than the improved coverage you are looking for.

Once you have taken those things into consideration you need a way to combine the antennas. It is possible to just use passive combiners, but you will have more control with an antenna "mixer" like the PWS DB-1C which lets you combine up to 4 antennas with variable level of each into a mix that is then DA'd to a bunch of outputs to feed various systems. Unfortunately there is no information on their website, and I don't remember the details of how many outputs, but it is often used in large scale situations. You would need 2 of the combiners to maintain diversity, 1 for each antenna system, with each system up to 4 antennas.

If you cannot isolate the coverage of the multiple antennas you are probably better off with an omni antenna, or a very wide coverage directional antenna that can cover the entire area of interest. You can get omni antennas that have a gain higher than zero that achieve the gain by reducing the vertical coverage while maintaining an omni horizontal pattern.

Mac
Logged

Jens Palm Bacher

  • Full Member
  • ***
  • Offline Offline
  • Posts: 192
    • Lydfabrikken
Re: Large RF coverage area, multiple antenna's
« Reply #5 on: December 21, 2013, 05:52:07 am »

What would the best way to combine 4 antennas into one distro, in order to provide coverage for an extremely wide area.
In the past i've used PW Helicals directed at almost 180∘ to each other to ensure mics are being covered by at least one antenna, however I lose any form of diversity, for mics at the far reaches.

Next time around I'd really want to add more helicals, in order to provide mics with true diversity, however the SHURE UA221 splitter/combiners seem a little "delicate" for the job.

Any recommendations would be apreciated.

To combine 2 sets of antennas the UA221 or Sennheiser ASP 212 is fine. The passive loss in the combiner can be compensated by cranking the antenna boosters up 3 db.
The expensive solution is http://www.wisycom.com/www3/products/product/mat243-mat283

As other have said, place the antennas to get the minimum overlap between the pairs.
Logged

Jerome Malsack

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 449
Re: Large RF coverage area, multiple antenna's
« Reply #6 on: December 21, 2013, 10:28:28 am »

On the other option of two receivers would using something like the shure scm810 smart mixer be able to detect the level of the receivers and activate the best signal.  Also providing the fail over with automatic switching. 

I understand that most of the technology is detected in the receiver for the best RF signal. 

With the antennae is it possible to put up a 10 or 20 foot mast and a pair of yagis in opposite directions, pointing down near the back of the crowd?  (prefer 20 foot)
Logged

Keith Broughton

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 430
Re: Large RF coverage area, multiple antenna's
« Reply #7 on: December 21, 2013, 02:53:51 pm »

When using multiple antennas to cover different zones you have to be very careful to be sure there is essentially no overlap in coverage.
Would  4 directional antennas pointing out covering 4 quadrants (at 10-2-4 and 8 o'clock) with an A_B_A_B pattern and the use  of the Shure passive combiners for the 2 A and 2 B antennas work?
That way, as mics "move" around the outlying coverage area, there would always be an A-B or B-A diversity available.
The A and B antennas would be "back to back" so they would not receive the same signal as long as the transmitters don't get too close to the receivers.
Of course, this doesn't take into account any reflected signals.
Logged

Mac Kerr

  • Old enough to know better
  • Administrator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3168
  • Audio Plumber
Re: Large RF coverage area, multiple antenna's
« Reply #8 on: December 21, 2013, 04:51:11 pm »

Would  4 directional antennas pointing out covering 4 quadrants (at 10-2-4 and 8 o'clock) with an A_B_A_B pattern and the use  of the Shure passive combiners for the 2 A and 2 B antennas work?
That way, as mics "move" around the outlying coverage area, there would always be an A-B or B-A diversity available.
The A and B antennas would be "back to back" so they would not receive the same signal as long as the transmitters don't get too close to the receivers.
Of course, this doesn't take into account any reflected signals.

If you want 360 coverage use a couple of omni antennas as a diversity pair. Your example gives up all diversity in favor of coverage. The ideal is to have full coverage and diversity, going to either extreme (diversity or coverage) just to use directional antennas does not seem like a step in the right direction.

If you are trying to solve a particular coverage problem, draw a map so we can see what you are trying to do.

Mac
Logged

Keith Broughton

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 430
Re: Large RF coverage area, multiple antenna's
« Reply #9 on: December 22, 2013, 06:49:45 am »

If you want 360 coverage use a couple of omni antennas as a diversity pair. Your example gives up all diversity in favor of coverage. The ideal is to have full coverage and diversity, going to either extreme (diversity or coverage) just to use directional antennas does not seem like a step in the right direction.

If you are trying to solve a particular coverage problem, draw a map so we can see what you are trying to do.

Mac
I was responding to the OPs question  relating to a wide area. I'm figuring the omnis didn't work out as he is using directional antennas.
He is trying to cover a large area and said he used only 2 directional antennas back to back and lost diversity.

Logged
Pages: [1] 2 3 4   Go Up
 


Page created in 0.093 seconds with 23 queries.