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Author Topic: Paddle Antennas  (Read 3653 times)

scottstephens

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Paddle Antennas
« on: June 17, 2018, 12:36:50 pm »

Hey all,

  I was just wondering, what is the correct distance to place paddles from each other?  This morning I was in church and noticed that the 2 active paddles were only a foot or so apart. I thought they had to be at least 6 feet or so apart to be effective; at least one wavelength.  I'm not sure why the church needs active paddles anyway, but I'm not on the crew there. Yippee and Thank God!!!!!

  Back in the day, when I toured, I was taught to keep them further apart. But that was when the only affordable option was VHF, (early 90's) but even later when I toured with a big country duo, (early 2000's) we kept them further apart than a couple of feet. Is it a technology changing thing or am I just woefully ignorant?

Thanks, all

Scott
 

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Jean-Pierre Coetzee

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Re: Paddle Antennas
« Reply #1 on: June 17, 2018, 01:02:00 pm »

1 wavelength. Remember for UHF the frequency is higher than VHF so for. 500MHz that would be around 2 feet which really isn't much higher it would be even less.
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Henry Cohen

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Re: Paddle Antennas
« Reply #2 on: June 17, 2018, 09:47:16 pm »

1 wavelength.

That's for any antenna, not just LPDA's ("paddle"), But one wavelength is only that general transition point between reactive near field and radiating near field; that means the antennas are still in each others' radiating near fields which can be a detriment to maximum performance. Best to get at least four to six wavelengths between the antennas to safely have them in each other's far field where they will have no real impact on performance.   
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Henry Cohen

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Lyle Williams

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Re: Paddle Antennas
« Reply #3 on: June 18, 2018, 03:51:25 am »

I would also make sure that they were set at 90degrees (or at least at some angle) to accomodate changing polarisations of incoming signals.

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Keith Broughton

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Re: Paddle Antennas
« Reply #4 on: June 18, 2018, 05:54:05 am »

that means the antennas are still in each others' radiating near fields which can be a detriment to maximum performance.
Now there is a bit of infoI didn't know.
Thanks Henry.
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Jerome Malsack

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Re: Paddle Antennas
« Reply #5 on: June 18, 2018, 08:51:43 am »

I still work with the VHF.  So one thing I do with my Omni antenna is I place them on opposite sides of the stage.  One in back of the stage, and the other out in front of the stage.  This allows the artist to turn in any direction and to still have line of site to either of the two antenna. 

My digital mixer and the wifi is 5 to 10 ft from the antenna for the wireless mics and body packs. 

I have wireless IEM for the mixer and that is 3 to 6 ft from the wifi.  So when doing the ipad and needing to hear the monitor sends I do not have to walk on stage.  This IEM is UHF and does have a passive paddle. 
« Last Edit: June 18, 2018, 08:55:39 am by Jerome Malsack »
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Justin Goodman

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Re: Paddle Antennas
« Reply #6 on: June 18, 2018, 04:08:19 pm »

Somewhat related ...  I've been wondering lately ... looking at a product like the RF Venue D-Fin ... could one not re-create essentially the exact effect with 2 LPDA's mounted on the same mic stand (one at 90 degrees horizontal with LP claw or similar)? 

Obviously you'd sacrifice some coverage area changing out omni whips for an LPDA, but you'd also benefit from rear rejection and forward gain from your horizontally polarized antenna if the performance area could be contained within the LPDA's coverage area. 

No?
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Henry Cohen

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Re: Paddle Antennas
« Reply #7 on: June 18, 2018, 06:39:33 pm »

Somewhat related ...  I've been wondering lately ... looking at a product like the RF Venue D-Fin ... could one not re-create essentially the exact effect with 2 LPDA's mounted on the same mic stand (one at 90 degrees horizontal with LP claw or similar)? 

Obviously you'd sacrifice some coverage area changing out omni whips for an LPDA, but you'd also benefit from rear rejection and forward gain from your horizontally polarized antenna if the performance area could be contained within the LPDA's coverage area. 

As with all things engineering and related deployments, it's all about compromise. Polar diversity without spacial separation has it's place, especially when space or visual approval is limited. With rare exception (especially given the relatively primitive and inexpensive RF technology used by wireless microphones as compared with state of the art cellular/LTE/PCS/AWS systems), spatial separation is one of the key factors for robust and reliable RF performance.
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Henry Cohen

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Justin Goodman

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Re: Paddle Antennas
« Reply #8 on: June 18, 2018, 09:29:17 pm »

As with all things engineering and related deployments, it's all about compromise. Polar diversity without spacial separation has it's place, especially when space or visual approval is limited. With rare exception (especially given the relatively primitive and inexpensive RF technology used by wireless microphones as compared with state of the art cellular/LTE/PCS/AWS systems), spatial separation is one of the key factors for robust and reliable RF performance.

As 90%+ of my AV work is wedding ceremonies, "visual approval is limited" essentially defines my expectations in most cases. Sometimes, I am able to set up well out of frame, but obviously the farther I get, that poses it's own set of potential issues.  300-500 ft away with spatial diversity or 100-150 feet away with polarization diversity only is the choice in many cases. 

I also have to be mindful of my tx antenna. Because weddings are often in makeshift sites and wedding planners aren't big fans of cables, I use battery powered wireless speakers with IEM packs (this feature actually gets me lots of high end work). A domed helical takes up a lot of visual real estate, but as the main output feed, there's no room for compromise there, and I'm already starting to push my "visual welcome." 
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Jason Glass

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Re: Paddle Antennas
« Reply #9 on: June 18, 2018, 10:30:34 pm »

300-500 ft away with spatial diversity or 100-150 feet away with polarization diversity only is the choice in many cases.

Guys, just place a pair of these
https://en-us.sennheiser.com/a-1031-u
flat on the floor at either side of the pulpit, up to 30' apart for diversity A&B, and connect them to your rig via low-loss cables such as 9913F7 or LMR-400, up to 100' long. Simple, rock solid RX, and invisible. Gaff taped to the floor or under a rug or carpet work fine. Even under nonmetallic set pieces, stairs, or risers works brilliantly.

If you doubt it, know that every Tonight Show done outside of 30 Rock for the last 4 years has used this method, under my direction. Even live to air from the Super Bowl. Twice. It works.

Sent from my Nexus 5 using Tapatalk
« Last Edit: June 18, 2018, 10:36:33 pm by Jason Glass »
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ProSoundWeb Community

Re: Paddle Antennas
« Reply #9 on: June 18, 2018, 10:30:34 pm »


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