Extending wireless antennas w/o distribution system

[jkowtko]

(I know I'll catch from flack for this, but --)

Looks like the FCC ban deadline is dragging out, and with our community theater finances worse than ever due to the recession, not really any chance of replacing our AKG WMS80 units in the near future.

So, for now I have all of the receivers up high on a wooden rack in the sound booth, a mere 30-40 feet from the stage, but I think the RF is still pretty weak.

The WMS80 units do not have detachable antennas, therefore no antenna distribution system options in the product design. They're not cheap anyway, so probably out of the question.

So short of moving the receiver rack away from the sound booth and closer to the stage, is there a way that I can effectively move the antennas only out closer to the stage?

I don't mind pulling apart the receivers and doing a bit of surgery here -- these units are old, and I have several backup receivers sitting in storage to use in case I make some fatal mistakes.

Thanks. John

[Footer]

Doubtful. If done wrong you could change the physical antenna design and actually make the problem worse. If you are having problems with 40' of airspace, your not going to get much better moving the antennas without putting them center stage. Buy a 100' snake and put the receivers onstage. You don't actually need to see the little lights.

[mbenonis]

Yeah, I think the best option is to move the receivers closer to the stage in your case - modifying the receivers to remote the antennas isn't a terribly good option if you don't have an electronics and RF lab at your disposal.

[Blah067]

Originally Posted by mbenonis

Yeah, I think the best option is to move the receivers closer to the stage in your case - modifying the receivers to remote the antennas isn't a terribly good option if you don't have an electronics and RF lab at your disposal.

+1 I agree.

[waynehoskins]

Yeah, just move them. It's probably better that way anyhow.

[FMEng]

You might find that putting the receivers in a different spot works better. For one thing, the metal top of the receiver acts as a ground plane for the antenna, which means the antenna doesn't pick up quite as well away from the back of the receiver. Orienting the receiver with its front toward the mics to take advantage of the ground plane does sometimes make a difference.

If you are using lav mics, the transmitters are usually on the back of the actors. Put the receivers at the back of the stage so that you don't have human flesh between them and the transmitter, most of the time.

[museav]

Originally Posted by jkowtko

(I know I'll catch from flack for this, but --)

Looks like the FCC ban deadline is dragging out, and with our community theater finances worse than ever due to the recession, not really any chance of replacing our AKG WMS80 units in the near future.

Not to give you flack, but just to be realistic, I believe those units operate at 710-746 MHz and while the 698-806 MHZ ban has not yet been enacted, my personal belief is that this is primarily due to the fact that some analog broadcasters are still operating in that spectrum and the ban proposed would thus have conflicted with the extension of the DTV transition deadline I would not be surprised to see the ban enacted not long after the June 12 transition date (unless that date is delayed at the last minute yet again), so whatever you do for those units may be a short term, as in a couple of months, solution.

Probably the last thing you'd want if the ban is enacted, or as the licensed users begin using their spectrum, is a device operating in that spectrum for which the antenna has been modified.

[dramatech]

generally speaking, without and electrically amplified antenna, the loss of signal in a long length of coax cable will probably be greater than the loss of signal in free air/line of sight. I went through this execise a few times a couple of years ago, and the math simply pointed out the futility of doing as you propose. The best bet without amplified antenna distribution is to get the receiving antenna as close as possible to the transmitting antenna.

[Chris15]

Originally Posted by dramatech

generally speaking, without and electrically amplified antenna, the loss of signal in a long length of coax cable will probably be greater than the loss of signal in free air/line of sight. I went through this execise a few times a couple of years ago, and the math simply pointed out the futility of doing as you propose. The best bet without amplified antenna distribution is to get the receiving antenna as close as possible to the transmitting antenna.

I'm sorry, but I feel your numbers are flawed. Let's look at some sums; Free space and coax losses increase with frequency. We'll use 900 MHz for the sake of comparison, it being a number on the data sheet I have handy.
For the sake of comparison, we'll take an unrealistic length of coax at 100m.
@900 MHz, RG58 (ZCG Scalar data sheet used for this) loses 35 dB.
The free space loss for 100m at 900 MHz is a mere 71.5 dB.
That's more than 35dB difference, meaning we have 3160 times more power when using coax.

So please explain to me why the coax is more lossy?
Amplified antenna distribution is a very broad statement, what do you mean by it?

[airkarol]

Send Phil Ladue a message. His username is avkid. We were working on something similar in his theatre last year, he'd know more about what was going on with it.