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Author Topic: RF Spotlight-style antenna for VHF?  (Read 1214 times)

Jason Glass

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Re: RF Spotlight-style antenna for VHF?
« Reply #10 on: March 24, 2019, 12:37:25 pm »

Hi All,

I was wondering if there was a similar unit for VHF?

I saw that Shure makes the UA860V, but it’s a bit different and more unsightly than RFVenue’s offering.

I have a friend doing interview-style video broadcasts, and the LED panel lights are apparently spewing RF hash. I recommended blackwrap on the backside of the panels and placing the panel in the null of the LPDA, but thought there might be other options.



You can place those LPDA's flat on the floor (as long as it's not made of conductive metal), located within a few feet of the TX and pointing toward the talent.  The closer the better, such as directly beneath them on the set.  They even work well under carpet or beneath wooden set risers.

This achieves minimum distance to the desired source of signal and maximum distance to the source of noise, which allows the inverse square law of free space loss to work in your favor to improve CNR.

This is exactly the same application and philosophy of the RF Spotlight that is designed as a low-gain antenna, but substituting a high-gain antenna in a way that makes it perform as a low-gain device.

Violation of near-field obstruction best practices and its associated antenna detuning in this case is desirable to reduce the overall gain of the system as appropriate for such a close range of operation.  VHF has very low loss in dB per foot through properly spec'd coax, so its length in that small room will likely be negligible.  You may even wish to insert more attenuation as Ike suggested.

If this configuration doesn't work perfectly in the scenario that you've described, there may be other problems happening in addition to noisy lighting fixtures and a deeper dive into your components and procedures is necessary.

Scott Helmke

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Re: RF Spotlight-style antenna for VHF?
« Reply #11 on: March 24, 2019, 03:18:55 pm »

I've been known to tape a standard half-wave (what comes with every Shure receiver except for the very cheapest) to something right in the middle of the action. Maybe taped to the back of a chair leg?
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Matthew Knischewsky

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Re: RF Spotlight-style antenna for VHF?
« Reply #12 on: March 24, 2019, 08:24:39 pm »

Knowing the production company, I’m almost certain it would have been discussed beforehand and the client demanded a wireless “solution”. They’re always “right”, right?

I hardwire whenever I can, at the very least for a backup to the backup’s backup, lol.

I’ve never been one to recommend a less-than-ideal solution to achieve a desired look/perception, but that’s not always my decision. Form over function is not my motto.

I had to make the suggestion! It would seem that some people forget that the simple solutions should be the most obvious. In my current role that happens all the time...
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Jordan Wolf

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Re: RF Spotlight-style antenna for VHF?
« Reply #13 on: March 24, 2019, 10:38:29 pm »

I've been known to tape a standard half-wave (what comes with every Shure receiver except for the very cheapest) to something right in the middle of the action. Maybe taped to the back of a chair leg?
Hmm...that’s a good thought. Maybe I’ll give that a try myself sometime!
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Jordan Wolf
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Jordan Wolf

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Re: RF Spotlight-style antenna for VHF?
« Reply #14 on: March 24, 2019, 10:39:31 pm »

I had to make the suggestion! It would seem that some people forget that the simple solutions should be the most obvious. In my current role that happens all the time...
Simple is better, in my experience, as well - less to go wrong, less to troubleshoot, etc.
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Jordan Wolf
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"We want our sound to go into the soul of the audience, and see if it can awaken some little thing in their minds... Cause there are so many sleeping people." - Jimi Hendrix

Jordan Wolf

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Re: RF Spotlight-style antenna for VHF?
« Reply #15 on: March 24, 2019, 10:40:06 pm »

You can place those LPDA's flat on the floor (as long as it's not made of conductive metal), located within a few feet of the TX and pointing toward the talent.  The closer the better, such as directly beneath them on the set.  They even work well under carpet or beneath wooden set risers.

This achieves minimum distance to the desired source of signal and maximum distance to the source of noise, which allows the inverse square law of free space loss to work in your favor to improve CNR.

This is exactly the same application and philosophy of the RF Spotlight that is designed as a low-gain antenna, but substituting a high-gain antenna in a way that makes it perform as a low-gain device.

Violation of near-field obstruction best practices and its associated antenna detuning in this case is desirable to reduce the overall gain of the system as appropriate for such a close range of operation.  VHF has very low loss in dB per foot through properly spec'd coax, so its length in that small room will likely be negligible.  You may even wish to insert more attenuation as Ike suggested.

If this configuration doesn't work perfectly in the scenario that you've described, there may be other problems happening in addition to noisy lighting fixtures and a deeper dive into your components and procedures is necessary.
Very interesting!
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Jordan Wolf
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"We want our sound to go into the soul of the audience, and see if it can awaken some little thing in their minds... Cause there are so many sleeping people." - Jimi Hendrix

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Re: RF Spotlight-style antenna for VHF?
« Reply #15 on: March 24, 2019, 10:40:06 pm »


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