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Author Topic: Antnenna splitters for wireless coms  (Read 3486 times)

Justice C. Bigler

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Antnenna splitters for wireless coms
« on: June 28, 2011, 05:09:39 pm »

I'm looking for a powered antenna splitter for wireless coms, analog UHF Clearcom WBS 680 or HME Pro850. I'll have four receiver/base stations (i.e. 8 antennas) and up to 16 belt packs. I'd like to have a pair of antennas close to the base units, and a pair in a remote location. The long cable run is going to be a good 300 feet for the remote antenna location. Basically I want four antennas total, two local and two remote, to split and connect to four different base units (4 in, 8 out?)

I seem to remember seeing something by Lectrosonics that would do the trick, but I'm not finding it on their website.
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Mac Kerr

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Re: Antnenna splitters for wireless coms
« Reply #1 on: June 29, 2011, 11:30:53 am »

I'm looking for a powered antenna splitter for wireless coms, analog UHF Clearcom WBS 680 or HME Pro850. I'll have four receiver/base stations (i.e. 8 antennas) and up to 16 belt packs. I'd like to have a pair of antennas close to the base units, and a pair in a remote location. The long cable run is going to be a good 300 feet for the remote antenna location. Basically I want four antennas total, two local and two remote, to split and connect to four different base units (4 in, 8 out?)

I seem to remember seeing something by Lectrosonics that would do the trick, but I'm not finding it on their website.

For the transmit side you can use a PWS GX4 IEM transmitter combiner feeding a passive transformer splitter. On the receive side you need 1/2 of a wireless mic antenna combiner, with the 2 antennas going through a passive antenna combiner before going into the antenna DA. On the end of that 300' run you want to use directional antennas to get some passive gain to make up for cable losses. You will also need to use very low loss cable. If this is a permanent install you might opt for LMR600 instead of LMR400 to get a little less loss.

Mac
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Karl Winkler

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Re: Antnenna splitters for wireless coms
« Reply #2 on: June 29, 2011, 11:50:08 am »

I'm looking for a powered antenna splitter for wireless coms, analog UHF Clearcom WBS 680 or HME Pro850. I'll have four receiver/base stations (i.e. 8 antennas) and up to 16 belt packs. I'd like to have a pair of antennas close to the base units, and a pair in a remote location. The long cable run is going to be a good 300 feet for the remote antenna location. Basically I want four antennas total, two local and two remote, to split and connect to four different base units (4 in, 8 out?)

I seem to remember seeing something by Lectrosonics that would do the trick, but I'm not finding it on their website.

The Lectrosonics unit is the UMC16B: http://www.lectrosonics.com/Multicouplers-Adapters/umc16b.html?qh=YToxOntpOjA7czo2OiJ1bWMxNmIiO30%3D

but it is only an active splitter - 2 in, 8 pairs of outs. It sounds like you'll need to combine your two antenna sets first, using a passive combiner.

We don't make any combiners, but AT does: http://www.audio-technica.com/cms/accessories/7dcbc90353fbf2e0/index.html

You'll probably also want RF amps at your remote antennas to drive the 300' of cable. http://www.lectrosonics.com/182-UFM230/View-details.html?qh=YToxOntpOjA7czo2OiJ1Zm0yMzAiO30%3D

That said - are these com units sending AND receiving RF? If so, the above suggestion won't work - the UMC16B is a receiving antenna splitter, not a combiner for transmitter signals.

-Karl



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Henry Cohen

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Re: Antnenna splitters for wireless coms
« Reply #3 on: June 29, 2011, 12:02:24 pm »

As per Mac, but with a few comments: How many outbound intercom channels (buses) are actually required, and how does that translate into the number of outbound RF channels based on bandsplits? The point is, you'll want a good quality IEM transmitter combiner, but you want to either turn off one or both transmitter(s) in each base station (and use a 4-way combiner), or get base stations that break out the two transmitters separately (and use an 8-way combiner) so you don't amplify (via the IEM transmit combiner) after the combining of amplifiers (inside the base station).

Start with one TX antenna deployed with a completely unobstructed near-field (6-8 wavelengths), up high. The choice of antenna will be based on coverage pattern required. Walk the entire operational area just listening to the transmission (via some signal source connected to the aux input); you'll be surprised at the propagation possible when the electromagnetic wave can properly launch from the radiating element. If the coverage is in fact inadequate, simply add a high powered passive two-way Wilkenson splitter and run your 300 feet of low loss coax (.4"OD, i.e. 9913, LMR400, CQ102, CQ106) to another antenna. Make sure the two antennas are RF isolated from each other by at least 20dB.

On the RX side, again ensure use of large diameter low loss coax and at least 20dB RF isolation between antennas. As Mac said, if this is a permanent install, LMR600 would be preferable on the RX side, especially over an RF amp, but that's easily determined by calculating out your RF gain structure.
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Justice C. Bigler

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Re: Antnenna splitters for wireless coms
« Reply #4 on: June 29, 2011, 02:08:35 pm »

As per Mac, but with a few comments: How many outbound intercom channels (buses) are actually required, and how does that translate into the number of outbound RF channels based on bandsplits?
I think I understand what you are asking. We have a two channel com system currently. However, the wireless com stations only run single channel. With our replacement I would like to give wireless access to both of the com channels. So, two channels, with up to 16 users on both channels. After rereading the HME Pro 850 specs it appears that I can use a single base station for up to 16 belt packs if I do not enable the latch function, which provides full duplex communication. Although I would like the system to operate exactly like the hard wired Clearcom system. But I'm not opposed to telling people that they have to push-to-talk.

Quote
The point is, you'll want a good quality IEM transmitter combiner, but you want to either turn off one or both transmitter(s) in each base station (and use a 4-way combiner), or get base stations that break out the two transmitters separately (and use an 8-way combiner) so you don't amplify (via the IEM transmit combiner) after the combining of amplifiers (inside the base station).
Perhaps I'm making this too complicated on myself? I guess there is no off the shelf product to combine and/or split antennas for wireless coms across several base stations?

Quote
Start with one TX antenna deployed with a completely unobstructed near-field (6-8 wavelengths), up high.
Just so that I know I'm workng in the right direction. Our current wireless com system, and older HME 800 runs in about the 471MHz range. For that system, to obtain a 6 to 8 wavelength clearance from any hard surface, I would need about 16 and 2/3 feet distance from any walls or floors or ceilings? Or am I misunderstanding you?

Quote
The choice of antenna will be based on coverage pattern required. Walk the entire operational area just listening to the transmission (via some signal source connected to the aux input); you'll be surprised at the propagation possible when the electromagnetic wave can properly launch from the radiating element. If the coverage is in fact inadequate, simply add a high powered passive two-way Wilkenson splitter and run your 300 feet of low loss coax (.4"OD, i.e. 9913, LMR400, CQ102, CQ106) to another antenna. Make sure the two antennas are RF isolated from each other by at least 20dB.

On the RX side, again ensure use of large diameter low loss coax and at least 20dB RF isolation between antennas. As Mac said, if this is a permanent install, LMR600 would be preferable on the RX side, especially over an RF amp, but that's easily determined by calculating out your RF gain structure.

Our current system is installed in the sound booth in the back of the hall. The antennas are on the back wall of that same hall, just on the other side of the sound booth. I would gladly relocate the receivers, but all the hard wired com stuff ties into that booth. Would it be possible that I would get better propagation back stage and downstairs where the dressing rooms are if the antennas were located on stage? Saving me the hassle of having to set up a remote antenna run and distribution?

I guess it's time to fire up the spectrum analyzer and see what's really going on.
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Henry Cohen

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Re: Antnenna splitters for wireless coms
« Reply #5 on: June 29, 2011, 03:03:37 pm »

As per Mac, but with a few comments: How many outbound intercom channels (buses) are actually required, and how does that translate into the number of outbound RF channels based on bandsplits?
I think I understand what you are asking. We have a two channel com system currently. However, the wireless com stations only run single channel. With our replacement I would like to give wireless access to both of the com channels. So, two channels, with up to 16 users on both channels. After rereading the HME Pro 850 specs it appears that I can use a single base station for up to 16 belt packs if I do not enable the latch function, which provides full duplex communication. Although I would like the system to operate exactly like the hard wired Clearcom system. But I'm not opposed to telling people that they have to push-to-talk.
With only two outgoing channels required, you could get a single Pro850, and put each beltpack into "busy channel lockout", which means a beltpack can't transmit if another beltpack [programmed to the same TX frequency] is transmitting. You still have full duplex communications, but only one beltpack on each of the four base station receivers can transmit at a time. This is certainly the most cost effective route as it negates the need for a TX combiner, RX multi-coupler and more than one base station. Only two passive two-way splitters are needed for two TX and two RX antennas.

In order to have all beltpacks capable of simultaneous transmission, four base stations are required with only one having its transmitters turned on. Now, only a RX multi-coupler and two two-way splitters are required, along with all beltpacks having the same RX (base TX) bandsplit.

Quote
Quote
The point is, you'll want a good quality IEM transmitter combiner, but you want to either turn off one or both transmitter(s) in each base station (and use a 4-way combiner), or get base stations that break out the two transmitters separately (and use an 8-way combiner) so you don't amplify (via the IEM transmit combiner) after the combining of amplifiers (inside the base station).
Perhaps I'm making this too complicated on myself? I guess there is no off the shelf product to combine and/or split antennas for wireless coms across several base stations?
Are you meaning the multiplexing of both TX and RX (of several base stations) onto a single coax and antenna, or do you mean combining the functions of a TX combiner and RX multi-coupler into a single rack mount chassis? If the former, it does not exist as an off the shelf plug and play device. If the latter, try to find a Telex SC-600, but you must still feed each TX input with only one transmitter, meaning you either have to turn off one (or both) TX in each base, or get the dual TX breakout option.

Quote
Quote
Start with one TX antenna deployed with a completely unobstructed near-field (6-8 wavelengths), up high.
Just so that I know I'm workng in the right direction. Our current wireless com system, and older HME 800 runs in about the 471MHz range. For that system, to obtain a 6 to 8 wavelength clearance from any hard surface, I would need about 16 and 2/3 feet distance from any walls or floors or ceilings? Or am I misunderstanding you?
You are correct. 471MHz is about 2.1 feet, so 12.6' - 16.8'.

Quote
Quote
The choice of antenna will be based on coverage pattern required. Walk the entire operational area just listening to the transmission (via some signal source connected to the aux input); you'll be surprised at the propagation possible when the electromagnetic wave can properly launch from the radiating element. If the coverage is in fact inadequate, simply add a high powered passive two-way Wilkenson splitter and run your 300 feet of low loss coax (.4"OD, i.e. 9913, LMR400, CQ102, CQ106) to another antenna. Make sure the two antennas are RF isolated from each other by at least 20dB.

On the RX side, again ensure use of large diameter low loss coax and at least 20dB RF isolation between antennas. As Mac said, if this is a permanent install, LMR600 would be preferable on the RX side, especially over an RF amp, but that's easily determined by calculating out your RF gain structure.

Our current system is installed in the sound booth in the back of the hall. The antennas are on the back wall of that same hall, just on the other side of the sound booth. I would gladly relocate the receivers, but all the hard wired com stuff ties into that booth. Would it be possible that I would get better propagation back stage and downstairs where the dressing rooms are if the antennas were located on stage? Saving me the hassle of having to set up a remote antenna run and distribution?

I guess it's time to fire up the spectrum analyzer and see what's really going on.
Certainly if you have or can borrow/rent the low loss coax of appropriate diameter in the lengths you're likely to need, and have the time, a test would prove most valuable. Place the antennas in what you beleive to be the optimum location for propagation and protection from movement of sets, people and carpenters, and see if you get the coverage you require. If not, my initial feeling is keep one set of antennas on the back of house wall where you currently have them and passively combine/split another pair in the offstage area needing coverage.
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Henry Cohen

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Re: Antnenna splitters for wireless coms
« Reply #5 on: June 29, 2011, 03:03:37 pm »


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