Helical Antenna Coil Direction

D

David Karol

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Jan 10, 2011
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Which direction should the coil spin for transmit / receive?

I'm using a few Professional Wireless helical antennas for Handhelds and IEMs.

I recall there being a specific way for each, but haven't used them in a while.

On gig with them now.

image-1349753133.jpg
 
Re: Helical Antenna Coil Direction

David Karol said:
Which direction should the coil spin for transmit / receive?

I'm using a few Professional Wireless helical antennas for Handhelds and IEMs.

I recall there being a specific way for each, but haven't used them in a while.

On gig with them now.
Click to expand...

It doesn't matter. If you have IEM transmit on the opposite side of the stage from your RF mic receive they should be opposite in twist, but if they are on the same side of the stage the pattern control of the antenna should be enough to keep the IEM transmit out of the mic receivers. AS always the diversity receive antennas should be a few wavelengths apart (6'), with the transmit separated as much as practical.

Mac
 
Re: Helical Antenna Coil Direction

If you're using helical antennas for something like a point-to-point link, then you want them to have the same rotation/twist/"sense" - like nuts on a threaded rod. If you're using them in a more standard setup for wireless mic receivers and/or IEM transmitters, it's good to have different sense between mics and IEM.
 
Re: Helical Antenna Coil Direction

It appears that the left and center helical in the picture have the same spin, and the right has an opposite spin than the other two. For what you're describing there is nothing wrong with your set-up, but like Mac mentioned(assuming the IEM transmit is in the center) the two receives should be farther apart than they are in the picture. Only thing that may improve the situation is switching the right and the center antenna, again assuming that the center(and shorter) antenna is your IEM transmitter.
 
Re: Helical Antenna Coil Direction

Thanks all.

Actually ended up using two paddles for the handhelds for other reasons.

Funny how when I scanned during our load-in, the area was pretty clean. By soundcheck there was a whole bunch of activity on top of the IEM frequencies; it all had move around again.

There were no RF issues during the show though. Two of the helicals were used, both for IEMs. Had ~12 IEMs (ew300), 8 Handhelds (UHF R).
 
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