Shure ULX Antenna

[Grog12]

Recently my wife (a costumer) asked me if I knew of any reason that a ULX body pack's atenna couldn't touch the skin of a performer. Apparently the SD/Engineer she has been working with was throwing fits about this happening.

Now I know we all use some form of sheath (whether a condom or something else) to protect the packs themselves, buy typicially I've seen the atenna sticking out.

Anyone got a good answer to this? The UG doesn't make mention of it at all.

[avkid]

Don't let it touch metal or coil it.
-
Not touching skin seems ridiculous, especially since I've been doing it for 5 years.

[Grog12]

Originally Posted by avkid

Don't let it touch metal or coil it.
-
Not touching skin seems ridiculous, especially since I've been doing it for 5 years.

Funny...that was my first reaction...almost word for word.

[mbenonis]

The reality of bodypack transmitters is that there is simply no ideal way to use them (OK, if you put them on a wooden stick in the middle of a field, 20 feet in the air, you'll get close to ideal). The body itself does all sorts of crazy things to the antenna's impedance, and there's nothing you can do about it. I would say that it shouldn't matter if the antenna is touching the skin, unless the insulation is gone and the antenna is making direct (ohmic) contact with the skin - in that case, just put electrical tape over it and call it a day. As far as metal goes, I would try to keep the antenna away as a general rule - it'll cause much more problems than the body will. Don't worry about coiling the antenna - it really doesn't make that big of a difference.

If you're having reception issues, the first thing I would do is move the receivers closer to the stage, and make sure you're not using massive amount of splitting without amplifying the signal. Also make sure your frequencies are coordinated properly and that there are no very strong signals in your bandsplit (i.e., a TV station) which might be desensitizing the receivers. These things will cause MUCH more in the way of problems than a coiled TX antenna.

[DaveySimps]

Although technically speaking, this could effect the overall response of the unit, I agree with the previous two posts, that it is not a real issue. I took a class with Gino Sigismoundi from Shure about RF issues and their mic systems. He did clearly state that an over all problem with RF systems in theatre is that you are, essentially, broadcasting through saltwater (the human body) before the signal gets to the receiver. He did say that, assuming the RF system is set up correctly (antennas in the right direction, use of distrobution systems, etc.) that any of their mic systems should not have any issues with this. It soulds like the Sound Designer in this instance is overly concerned with somehting so minute that it is ridiculous.

~Dave

[avare]

I have had transmission failures when the antenna touched moist (sweaty) skin. It can cause a problem. It is not as dramatic (pun intended) or against code, but would you not repair broken ground pins on electrical plugs you have because no one has ever had been electrocuted while working with you yet?

Andre

[Grog12]

avare? Was it a recreatable problem?

Here's why I ask......I've been asking this question around ALOT lately and you're the first person with the issue.

[mbenonis]

avare, did the radiating element actually touch the person? I.e., the metal part of the antenna and not just the rubber coating on the wire? I would suspect that it was actually a metal-on-skin contact to cause a transmitter failure...

[avare]

The outside plastic/rubber cover on the antenna.

No, I did not try to recreate the problem. I solved it immediately. Think about it. The wet body acts like a huge capacitor plate.

If you are certain that you performers do not sweat, then don't worry about it.

Paraphrasing slightly, an amateur sets up so it can work right. a professional tries to set up the system so it can't go wrong, wherever predictable.

Andre

[Grog12]

Originally Posted by avare

The outside plastic/rubber cover on the antenna.
No, I did not try to recreate the problem. I solved it immediately. Think about it. The wet body acts like a huge capacitor plate.
If you are certain that you performers do not sweat, then don't worry about it.
Paraphrasing slightly, an amateur sets up so it can work right. a professional tries to set up the system so it can't go wrong, wherever predictable.
Andre

While I'm mildly insulted that you insinuate I'm not a proffesional...I have a feeling that's not your intent.

Yes the human body acts as a large capacitor plate. But its going to do that whether or not the anntenna touches the skin.

Part of troubleshooting is knowing exactly what a problem is and not just assuming. Hence my question of was the problem recreatable. If you pull the atenna off the skin and it works touch it to the skin and it fails again there are about 5 other things that could be the problem; Loose attena connection being the first that pops to mind.