[Discuss] Antenna Signal Issues

Wed Jun 4 15:46:55 EDT 2014

I'm a sound guy with experience in wireless.
I don't know from your post if you're having dropouts on the mic side or
the monitor side of the equation.

First off forget about combining antennas for mics and monitors.
Nevermind the different manufacturers, the 566MHz and 2.4GHz are different
areas of radio spectrum, so an antenna built to be efficient in one range
won't be for the other.
With only 4 wireless mics, I don't think an active antenna distro would
make sense.
They're pricey and add bulk to the equipment rack.

Modern wireless systems usually have a frequency scanning feature, learn
how to take advantage of this automatic channel finding feature. Start with
all transmitters off, do a channel scan on the first receiver, sync the
first mic to it and leave it on. Now scan with the second receiver, sync
that mic and so on.
I remember the old days we had to research ahead of time to know what radio
and tv stations were in the area and what band our mics used and then
determine how few channels were left available to use wireless.

Do your best to have the receiving antennas above the heads of the crowd,
open the rack's back lid and use fresh batteries in the transmitters.
Bodies block and absorb RF signals, make sure the belt pack antennas are
free and not hidden under arms or tucked in next to the skin. On hand-held
mics make sure to know where the antenna is on the unit (usually the bottom
tip area) and have the performer avoid holding the mic there.

On to the in-ears:

Eight transmitters close together may cause inter-modulation.
If they're all in one rack, you might want to separate some.
Perhaps 4 and 4, then put the second rack in another location on stage near
the performers using them, then use cables or a sub-snake to get the mixed
signals to them.
Another solution may be to use an antenna combiner like this:
http://en-us.sennheiser.com/ac-3 IF that is in fact the problem. It look
like you would need two of those for your rig if you go this route.

Ask yourself: Are any two or more units transmitting a nearly identical
monitor mix?
If so, you may want to just have more than one performer tune their belt
pack receiver to the same transmitter frequency. It's similar to having
many people listening to the same radio station. The trade-off is that the
people sharing the mix won't be able to ask for "more me" in the mix
without conflict. Remember, this trick doesn't work for microphones, each
transmitter needs it's own frequency but many receivers can tune in.

Same rules apply for the antennas as with the mics.
Get them high and open to the air. Make sure each performer has a clear
line of sight to the transmitter antennas and wears their belt pack on the
side facing the antennas.
use the frequency finding feature of the system to find clean channels one
at a time with the previous transmitter still on.

I always try the easiest, cheapest solutions first. Simpler is better.

Stu

On Wed, Jun 4, 2014 at 12:00 PM, <discuss-request at blu.org> wrote:

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> Today's Topics:
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>    1. Antenna Signal Issues (Matt Shields)
>    2. Re: Antenna Signal Issues (Bill Horne)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 4 Jun 2014 09:25:05 -0400
> From: Matt Shields <matt at mattshields.org>
> To: discuss at blu.org
> Subject: [Discuss] Antenna Signal Issues
> Message-ID:
>         <
> CAOTD2YRqNRmFOxYEBOoXwEAWKCo1K1WqS3YwP87UiRk1v_iihA at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> This is not computer or linux related but I'm hoping that someone on the
> list might have some technical experience in radio signals or wireless
> systems for audio engineering.
>
> I have the following wireless equipment.  2 wireless handheld mics, 2
> wireless headset mics and 8 in ear wireless monitor systems(IEM).  We're
> having issues with signal dropout probably due to antenna issues, those
> cheap plastic ones that come with the units.  Both the handheld and headset
> mics run on the 2.4Ghz spectrum and the IEM's run on 566-608Mhz.  We have
> already figured out which frequencies work best for the environment, so
> that's not an issue and we don't have any conflicts with WIFI.
>
> So the issue we think we have is range issue.  Can I buy a high gain
> directional antenna and a splitter and run cables to each of the
> devices(single antenna array)?  Or do I need to have the mic's and IEM's
> use 2 separate antenna's since one is send and one is receive?  Or do I
> need to have every system use a separate antenna?
>
> A few years back I did something similar with my WIFI router, bought a
> larger +12dbi gain omnidirectional antenna and my range almost doubled.
>  The idea is that if I get a more directional antenna I should get a decent
> amount of gain.
>
> Here's the equipment I'm using:
> 2x Line 6 XD-V75 - handheld wireless mics
> 2x Line 6 XD-V55HS - headset wireless mics
> 8x Sennheiser EW300IEMG3-G - In Ear Wireless Monitor
>
> Matt
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 04 Jun 2014 11:37:31 -0400
> From: Bill Horne <bill at horne.net>
> To: BLU Discussion List <discuss at blu.org>
> Subject: Re: [Discuss] Antenna Signal Issues
> Message-ID: <538F3D3B.5060102 at horne.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> On 6/4/2014 9:25 AM, Matt Shields wrote:
> > This is not computer or linux related but I'm hoping that someone on the
> > list might have some technical experience in radio signals or wireless
> > systems for audio engineering.
>
> Wouldn't you rather talk about DMARC? ;-)
>
> > I have the following wireless equipment.  ...
> >
> > So the issue we think we have is range issue.  Can I buy a high gain
> > directional antenna and a splitter and run cables to each of the
> > devices(single antenna array)?  Or do I need to have the mic's and IEM's
> > use 2 separate antenna's since one is send and one is receive?  Or do I
> > need to have every system use a separate antenna?
>
> Splitters cost power; as much as 1/2 of your power can be lost when
> using them.
>
> Directional antennas are a double-edged sword: you get /some/added gain
> in /some/ direction, but they are never perfect, and will tend to leave
> dead spots in odd places.
>
> I suggest you start simply: elevate the transmitters and receivers above
> the floor as much as you can, for example, by placing them on top of
> emergency lights. Try to get wireless mic receivers out in the middle of
> the crowd instead of on the stage: they work better when tied to
> ceiling-mounted video projectors in the middle of the room.
>
> Let us know how well that works. Simplest is always better.
>
> Bill
>
> --
> Bill Horne
> William Warren Consulting
> 339-364-8487
>
>
>
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> End of Discuss Digest, Vol 37, Issue 2
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-- 
Thanks,
Stu

617-462-0552
genuineaudio at gmail.com
blue23 at netzero.net
stuart.conner at state.ma.us

Stuart Conner
62 Rhodes Cir
Hingham, MA 02043