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Title: Paddle Antennas
Post by: scottstephens 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
 

Title: Re: Paddle Antennas
Post by: Jean-Pierre Coetzee 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.
Title: Re: Paddle Antennas
Post by: Henry Cohen 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.   
Title: Re: Paddle Antennas
Post by: Lyle Williams 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.

Title: Re: Paddle Antennas
Post by: Keith Broughton 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.
Title: Re: Paddle Antennas
Post by: Jerome Malsack 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. 
Title: Re: Paddle Antennas
Post by: Justin Goodman 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?
Title: Re: Paddle Antennas
Post by: Henry Cohen 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.
Title: Re: Paddle Antennas
Post by: Justin Goodman 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." 
Title: Re: Paddle Antennas
Post by: Jason Glass 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
Title: Re: Paddle Antennas
Post by: brian maddox on June 18, 2018, 11:21:56 pm
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

This is going in my trick box.
Title: Re: Paddle Antennas
Post by: Jason Glass on June 18, 2018, 11:42:01 pm
This is going in my trick box.


Just be mindful of their donut pattern in vertical orientation, which becomes a figure-8 when placed horizontally on the floor. You'll be surprised by their range perpendicular to their axis.

Sent from my Nexus 5 using Tapatalk

Title: Re: Paddle Antennas
Post by: Mike Caldwell on June 18, 2018, 11:44:08 pm
RF Venue has a floor pad antenna call the RF Spotlight.
Never used one but it looks interesting.
Title: Re: Paddle Antennas
Post by: Jason Glass on June 18, 2018, 11:47:00 pm
RF Venue has a floor pad antenna call the RF Spotlight.
Never used one but it looks interesting.
It's a great low-gain antenna with a hemispherical pattern, and works wonderfully for its designed application. However, it's pricey.

Sent from my Nexus 5 using Tapatalk

Title: Re: Paddle Antennas
Post by: Ike Zimbel on June 19, 2018, 07:31:17 am
RF Venue has a floor pad antenna call the RF Spotlight.
Never used one but it looks interesting.
I've used them for both Tx and Rx. They're great when you want / need to localize things. For example I've used them successfully a couple of times for the IEM Tx for the live band segment of the NHL outdoor hockey games I've done. My reasoning was this: In a coordination of up to 300 frequencies, why would I want to be spraying 8-16 fairly strong Tx all over the venue for one 20 minute segment? Sightlines are also a big issue on that gig because the stage is a flat deck between the stands and the rink.
On both occasions the band was Bryan Adams. On the first one they said it worked fine for the performance but things were a bit iffy in the offstage area. On the second one, I added a local whip to the monitor position which took care of that. First show, the mat was just on the deck, downstage center-ish, the 2nd one, the monitor tech put it under the deck and that worked fine too.
Title: Re: Paddle Antennas
Post by: Robert Piascik on June 19, 2018, 09:09:57 am
....just place a pair of these
https://en-us.sennheiser.com/a-1031-u
flat on the floor at either side...

Is there a Shure equivalent or does it matter?
Title: Re: Paddle Antennas
Post by: Pete Erskine on June 19, 2018, 09:24:49 am
Is there a Shure equivalent or does it matter?

Shure UA860 and  Lectrosonics SNA600A (my always bu antenna) would react the same

Strange how often I see the UA860 pointed top to the stage
Title: Re: Paddle Antennas
Post by: Ike Zimbel on June 19, 2018, 12:21:43 pm
Shure UA860 and  Lectrosonics SNA600A (my always bu antenna) would react the same

Strange how often I see the UA860 pointed top to the stage
I'm using a couple of pairs of those too!
Title: Re: Paddle Antennas
Post by: Justin Goodman on June 19, 2018, 01:36:10 pm
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

Sadly wedding planners are allergic to cables of any kind getting near their wedding altars. Before I went full wireless, I tried to put a small rack of rx's (powered with a portable power bank directly with DC) off to the side and then just run mic cable back to my FOH station, but even that amount of cabling often won't work (both visually and for time constraints).

Wedding venues that aren't hotels are often small and have limited load in that has to be time coordinated with floral and catering ALWAYS getting priority.  I'm usually given almost an hour to set up the PA, do a basic frequency coord, ring out feedback, and soundcheck before guests arrive and 15-20 minutes to break down (the latter being the more difficult constraint) to be out of the way for cocktail hour.  So what I've done is inboarded absolutely everything and gone to IEM tx + IEM rx and battery powered speaker for PA.  15-20 minutes up and 5-10 minutes down. 

Ultimately all wedding planners know is that their Bluetooth Bose Soundbox works wirelessly and can set up in 15 seconds with no wires, so there's no reason a professional like me can't get the same done in an hour. 
Title: Re: Paddle Antennas
Post by: Mike Caldwell on June 19, 2018, 06:21:47 pm
Sadly wedding planners are allergic to cables of any kind getting near their wedding altars. Before I went full wireless, I tried to put a small rack of rx's (powered with a portable power bank directly with DC) off to the side and then just run mic cable back to my FOH station, but even that amount of cabling often won't work (both visually and for time constraints).

Wedding venues that aren't hotels are often small and have limited load in that has to be time coordinated with floral and catering ALWAYS getting priority.  I'm usually given almost an hour to set up the PA, do a basic frequency coord, ring out feedback, and soundcheck before guests arrive and 15-20 minutes to break down (the latter being the more difficult constraint) to be out of the way for cocktail hour.  So what I've done is inboarded absolutely everything and gone to IEM tx + IEM rx and battery powered speaker for PA.  15-20 minutes up and 5-10 minutes down. 

Ultimately all wedding planners know is that their Bluetooth Bose Soundbox works wirelessly and can set up in 15 seconds with no wires, so there's no reason a professional like me can't get the same done in an hour.

The use of anything with a wire or cord makes you look like a caveman soundman in their eyes.
Title: Re: Paddle Antennas
Post by: Ike Zimbel on June 19, 2018, 06:39:10 pm
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
I would call this a "flooral arrangement" ;). Jason, do you take the mic stand mounts off them to make them flatter?
Title: Re: Paddle Antennas
Post by: Mark Cadwallader on June 19, 2018, 06:42:40 pm
It is supposed to look like (and sound like) it does on TV and in the movies. "If they can make it happen, why can't you?"
Title: Re: Paddle Antennas
Post by: Jason Glass on June 19, 2018, 06:44:05 pm
I would call this a "flooral arrangement" ;). Jason, do you take the mic stand mounts off them to make them flatter?
Yes, I do!

Sent from my Nexus 5 using Tapatalk

Title: Re: Paddle Antennas
Post by: Jerome Malsack on June 20, 2018, 09:39:24 am
And for the weddings do you color coordinate the antenna to hide in the color scheme or wall paint.   

And another crazy question.  With the ground being so close to the antenna elements is there a preferred elevation off the ground for best reception.  Just as we would want the 1/4 wave length from metal objects.  Do you want the 1/4 wave length above the ground or earth. 
Title: Re: Paddle Antennas
Post by: Jason Glass on June 20, 2018, 01:09:47 pm
And for the weddings do you color coordinate the antenna to hide in the color scheme or wall paint.   

And another crazy question.  With the ground being so close to the antenna elements is there a preferred elevation off the ground for best reception.  Just as we would want the 1/4 wave length from metal objects.  Do you want the 1/4 wave length above the ground or earth.
Like just about everything in RF engineering, this is a compromise, and it's far outside of the intended use of the antenna's design. Of course placing them flat on the floor will reduce their gain and alter their pattern, but I have found that it works well, without delving deeper into any benefit of spacing them away from the surface. Of course, I don't think it would work very well on a metallic surface, and in that case I'm sure that spacing would be critical.

Sent from my Nexus 5 using Tapatalk

Title: Re: Paddle Antennas
Post by: Lyle Williams on June 21, 2018, 08:44:50 am
I have some interesting Russian antenna books, written in the early '90s when the USSR had fallen.

HF/LF Antennas with all elements below ground (so as to survive a large blast).  They just aren't very efficient.  Add some great stonking Russian transmitter tubes, and who cares?

There were also interesting VHF/UHF directional antenna designs cut from foil and laid under wallpaper or carpet.

Antenna ingenuity is a wonderful thing.
Title: Re: Paddle Antennas
Post by: Don Boomer on June 21, 2018, 10:23:56 am
Like just about everything in RF engineering, this is a compromise, and it's far outside of the intended use of the antenna's design. Of course placing them flat on the floor will reduce their gain and alter their pattern, but I have found that it works well, without delving deeper into any benefit of spacing them away from the surface. Of course, I don't think it would work very well on a metallic surface, and in that case I'm sure that spacing would be critical.

Pardon my spam, but I just wanted to point out that “magnetic” antennas like the RFV Spotlight Ike refered to earlier are reasonable immune from the capacitive reactance that conventional “electrical” antennas (paddles, whips, helicals) suffer from when placed on the ground. They also aren’t bothered when placed on a metal deck (as they sit flat on the floor).
Title: Re: Paddle Antennas
Post by: Joris Jans2 on July 21, 2018, 12:07:35 pm
from Shure's website: http://blog.shure.com/wireless-systems-and-antenna-placement/

Quote
Locate diversity receiver antennas a suitable distance apart. For diversity reception, the minimum separation for significant benefit is one-quarter wavelength. The effect improves somewhat up to a separation of about one wavelength. Diversity performance does not change substantially beyond this separation distance. However, in some large area applications, overall coverage may be improved by further separation. In these cases one or both antennas may be located to provide a shorter average distance to the transmitter(s) throughout the operating area.
Title: Re: Paddle Antennas
Post by: Henry Cohen on July 21, 2018, 01:57:59 pm
from Shure's website: http://blog.shure.com/wireless-systems-and-antenna-placement/
Quote
Locate diversity receiver antennas a suitable distance apart. For diversity reception, the minimum separation for significant benefit is one-quarter wavelength. The effect improves somewhat up to a separation of about one wavelength. Diversity performance does not change substantially beyond this separation distance . . .

This advice is mathematically correct as far as mitigating dropouts due to multipath [cancellation], but ignores the fact that a spatial separation of only 1/4 wavelength puts the antennas in each others' near fields and thus will cause other problems. Always best to strive for at least one wavelength separation (at the lowest frequency of interest), more if possible.
Title: Re: Paddle Antennas
Post by: Jay Barracato on July 22, 2018, 12:23:23 pm


This advice is mathematically correct as far as mitigating dropouts due to multipath [cancellation], but ignores the fact that a spatial separation of only 1/4 wavelength puts the antennas in each others' near fields and thus will cause other problems. Always best to strive for at least one wavelength separation (at the lowest frequency of interest), more if possible.
So rule of thumb anything 300 MHz or up should be good with 1 m of separation.

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Title: Re: Paddle Antennas
Post by: Henry Cohen on July 22, 2018, 09:21:38 pm
So rule of thumb anything 300 MHz or up should be good with 1 m of separation.

And for you imperialists, 2' (24") at UHF frequencies is a good rule of thumb.