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[Michael 'Bink' Knowles]

Quote:

...Try angling your paddles about 40-45deg from vertical and see if that helps...

I agree and I was told that the main point of this was to get a 90-degree angle between your paddles so as to pick up the different polarities of the RF signal. With this in mind, wouldn't a vertical paddle and a horizontal paddle make more sense? This is easier to achieve by using a straight mic stand for the vertical one and a guitar clamp mic adaptor for the horizontal one. Would the horizontal paddle pick up better or worse because it was parallel to the ground?

-Bink

[Rex Ray]

Hi,Bink!
 The only thing about horizontal polarity with a Yagi/LP would
be that half the juice is going into the ground,and what isn't might come back as multipath reflections....remember "picket-fencing" in car FM before diversity rcvrs?
Why not a parabolic on the follow spot? hehehe
Rex

[Michael 'Bink' Knowles]

Rex Ray wrote on Wed, 05 October 2005 08:37

...The only thing about horizontal polarity with a Yagi/LP would be that half the juice is going into the ground,and what isn't might come back as multipath reflections....remember "picket-fencing" in car FM before diversity rcvrs?...

Good point. I guess it's time to invest in a couple of short angle arms for the mic stands.  




Bink

[Mac Kerr]

Michael 'Bink' Knowles wrote on Wed, 05 October 2005 10:57

I agree and I was told that the main point of this was to get a 90-degree angle between your paddles so as to pick up the different polarities of the RF signal. With this in mind, wouldn't a vertical paddle and a horizontal paddle make more sense? This is easier to achieve by using a straight mic stand for the vertical one and a guitar clamp mic adaptor for the horizontal one. Would the horizontal paddle pick up better or worse because it was parallel to the ground? -Bink

This discussion is about IEM transmitter antennas, I hope there are not multiple antennas on a single transmitter. If the post about putting a paddle on each side of the stage implied that there were 2 transmit antennas on a single transmitter, that could be part of the problem. There will be plenty of multipath without manufacturing your own. Wireless mic antenna systems combine multiple antennas into a single feed (DA), IEM antenna couplers combine multiple transmitters into a single antenna. Antenna couplers can be very frequency sensitive as they are tuned to each transmitter. Changing transmitter frequencies looking for open channels can have a detrimental effect on the performance of the coupler.

Mac

[Bennett Prescott]

I obviously don't know what I'm talking about, but if a good pair of moderately directional antennas isn't enough, wouldn't something like the Professional Wireless GX4 <http://www.professionalwireless.com/02_custom.htm> be the next logical step? If your transmitters aren't putting out the maximum allowed wattage (250mW), this'll make 'em.

A decent helical antenna will have 14dbi of gain or so, but with a 50-degree beamwidth you'd better have pretty creative positioning capabilities.

[Michael 'Bink' Knowles]

Ah, yes, thanks for the brotherly bitch-slap. I'm sure Rex was talking about ONE transmitting paddle antenna positioned at a 45-degree angle to the ground. Me? I was getting confused between transmitting and receiving, as you no doubt noticed.

-Bink  

[Mac Kerr]

[Dave Stevens]

Bennett Prescott wrote on Wed, 05 October 2005 11:38

I obviously don't know what I'm talking about, but if a good pair of moderately directional antennas isn't enough, wouldn't something like the Professional Wireless GX4 <http://www.professionalwireless.com/02_custom.htm> be the next logical step? If your transmitters aren't putting out the maximum allowed wattage (250mW), this'll make 'em. A decent helical antenna will have 14dbi of gain or so, but with a 50-degree beamwidth you'd better have pretty creative positioning capabilities.

There is more to the equation than transmission strength.  Combiners are used as well and that Systems unit shown is just a Varsity version of what folks like Shure and Sennhieser build.  You need both good antenna rigs and a worthy combiner and I've had pretty good luck with the stock factory combiners most of the time.

A couple of reasons to use a helical are polarization and rejection.  You can read up on the Systems  Helical datasheet  from the same page you reference for a basic explaination.  I was able to do some of my research at the engineering library at UW.  What one is doing is broadcasting UHF.  For ears it's from the sound guy to the performer, for mics it's from the performer to the soundguy.  As long as one has a basic understanding of how broadcasting works it will help when implementing or attempting to troubleshoot RF apps and issues.  Lectrosonics have a good paper and Karl told me a couple weeks ago they were updating it.  That's a good place to start.

Dave

[Bennett Prescott]

Now you've got me fascinated. If you see a blonde guy walking into things at AES holding a few turns of wire, that'll be me.

[Mike MacWillie]

What frequency range to IEM's opperate on?



I'm not knowledgable in IEM's, but I do have a very good understanding of antennas and FCC regulations for 2.4Ghz and 5.8Ghz Wireless applications.

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