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Author Topic: "new"VHF Band for mics  (Read 6137 times)

Lyle Williams

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Re: "new"VHF Band for mics
« Reply #10 on: August 15, 2016, 04:47:50 pm »

In Australia when there was a recent restack to clear out 700MHz, half the TV channels ended up in this VHF band.
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Karl Winkler

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Re: "new"VHF Band for mics
« Reply #11 on: August 24, 2016, 11:30:48 am »

I believe that it's 174-216 MHz, however I just got the Canadian price list this morning and they're not on it yet. I heard from a reliable source that they are waiting on Industry Canada approval.
iz

Ike is correct: the band is 174-216 MHz. We (Lectrosonics) have an IFB system out in that band as well.
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Ike Zimbel

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Re: "new"VHF Band for mics
« Reply #12 on: August 24, 2016, 11:51:18 am »

Ike is correct: the band is 174-216 MHz. We (Lectrosonics) have an IFB system out in that band as well.
Yes, and those ARE available in Canada right now! I was just looking at one yesterday...the usual solid Lectrosonics build, looks like a winner.
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~Ike Zimbel~
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Ike Zimbel

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Re: "new"VHF Band for mics
« Reply #13 on: December 03, 2016, 01:55:09 pm »

Yes, and those ARE available in Canada right now! I was just looking at one yesterday...the usual solid Lectrosonics build, looks like a winner.
This just in:http://www.prosoundweb.com/article/shure_adds_vhf_frequency_bands_ulx-d_and_qlx-d_digital_wireless_systems/news
Not sure about Canada yet, but will report back as soon as I know.
iz
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~Ike Zimbel~
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Alteros Inc
Radio Active Designs
~416-720-0887~
ca.linkedin.com/pub/ike-zimbel/48/aa1/266

Jason Glass

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Re: "new"VHF Band for mics
« Reply #14 on: December 03, 2016, 10:00:28 pm »

This just in:http://www.prosoundweb.com/article/shure_adds_vhf_frequency_bands_ulx-d_and_qlx-d_digital_wireless_systems/news
Not sure about Canada yet, but will report back as soon as I know.
iz

FYI, their new UA860V omni antennas work great for RAD UV-1G intercom RX, and are very small in size for VHF remote antennas.

Scott Holtzman

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Re: "new"VHF Band for mics
« Reply #15 on: December 04, 2016, 03:47:16 am »

FYI, their new UA860V omni antennas work great for RAD UV-1G intercom RX, and are very small in size for VHF remote antennas.

The built in ground plane is a decent idea however in principal I am always very leery of the performance of antenna that are not larger than a 1/4 wavelength.

While these are not production specific knowledge RF is RF and it baffles me that we readily accept that a horn has to be the right size to obtain pattern control down to a specific frequency it seems that the same principals applied to RF are seen as able to be engineered around.

You can certainly fix impedance problems of improperly loaded antenna with some type of network or "tank" circuit but the radiated (or captured) energy will never be the same as a reference dipole.

Gain in an antenna is achieved just like sound, my compressing the pattern and redirecting the energy into the desired direction.  RX antenna work the same, they give up sensitivity in one part of the pattern and increase it in another.

I have some older VHF T-Band Samson radios that were marketed to the broadcast industry and have synthesized RX and TX.  The main issue with the is oscillator drift and twice a year they need to be 0 beated (I don't have a trued service monitor any more).  I use a very standard 1/4 wave ground plane on a light stand.  The radials are 23" or so.  Whatever the center frequency is.  It is large but it works very well.  The preamp in the distro is set to only provide enough amplification to overcome multicoupler and cabling loss.  The only wish I have is that some sort of front end was on that amp, it is like a barn dorn and you can see the noise floor come up in urban areas.  I am sure that signals are mixing in the preamp.



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Keith Broughton

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Re: "new"VHF Band for mics
« Reply #16 on: December 04, 2016, 07:14:22 am »

FYI, their new UA860V omni antennas work great for RAD UV-1G intercom RX, and are very small in size for VHF remote antennas.
Considering a wavelenght at 200 Mhz is around 60", would this be a 1/4 wave or 1/8?
Hard to tell from the pic.
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Jason Glass

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Re: "new"VHF Band for mics
« Reply #17 on: December 04, 2016, 08:49:06 am »

Considering a wavelenght at 200 Mhz is around 60", would this be a 1/4 wave or 1/8?
Hard to tell from the pic.

It's a UA8-174-216 coil-loaded 1/4λ monopole on a detachable ground plane that contains a coaxial delay line.  The original prototypes that I tested had a different impedance matching device.

http://www.shure.com/americas/products/accessories/wireless-systems/wireless-systems-antennas/ua8-174-216

http://www.shure.com/americas/products/accessories/wireless-systems/wireless-systems-antennas/ua860v-passive-omnidirectional-antenna

One can reasonably assume that the antenna has dimensions appreciably less than what one would expect for 1/4λ @ 174-216 MHz due to computer aided design with 3D NEC modeling of electromagnetic radiation patterns.  My guess is that Shure has much more advanced software than 4NEC2.   ;)  I have seen tech articles describing sub-1/4λ antenna designs for space systems' use that seem impossibly small, yet perform remarkably well.  Usually they're fractal or meander designs, so this may be irrelevant to this ground plane's geometry, but I can imagine that there might be something similar going on with the rounded diamond shape.  Then again, maybe not!

https://www.nasa.gov/centers/ames/news/releases/2004/04_55AR.html

https://www.nasa.gov/centers/ames/news/releases/2004/antenna/antenna.html

Keith Broughton

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Re: "new"VHF Band for mics
« Reply #18 on: December 04, 2016, 04:29:25 pm »

It's a UA8-174-216 coil-loaded 1/4λ monopole on a detachable ground plane that contains a coaxial delay line.  The original prototypes that I tested had a different impedance matching device.

http://www.shure.com/americas/products/accessories/wireless-systems/wireless-systems-antennas/ua8-174-216

http://www.shure.com/americas/products/accessories/wireless-systems/wireless-systems-antennas/ua860v-passive-omnidirectional-antenna

One can reasonably assume that the antenna has dimensions appreciably less than what one would expect for 1/4λ @ 174-216 MHz due to computer aided design with 3D NEC modeling of electromagnetic radiation patterns.  My guess is that Shure has much more advanced software than 4NEC2.   ;)  I have seen tech articles describing sub-1/4λ antenna designs for space systems' use that seem impossibly small, yet perform remarkably well.  Usually they're fractal or meander designs, so this may be irrelevant to this ground plane's geometry, but I can imagine that there might be something similar going on with the rounded diamond shape.  Then again, maybe not!

https://www.nasa.gov/centers/ames/news/releases/2004/04_55AR.html

https://www.nasa.gov/centers/ames/news/releases/2004/antenna/antenna.html
$37 for just the antenna and another $300 for a piece of metal and a mic stand adapter...oh and a few feet of coax. Yikes!
Is there something else I don't see?
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Scott Holtzman

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Re: "new"VHF Band for mics
« Reply #19 on: December 04, 2016, 04:37:26 pm »

It's a UA8-174-216 coil-loaded 1/4λ monopole on a detachable ground plane that contains a coaxial delay line.  The original prototypes that I tested had a different impedance matching device.

http://www.shure.com/americas/products/accessories/wireless-systems/wireless-systems-antennas/ua8-174-216

http://www.shure.com/americas/products/accessories/wireless-systems/wireless-systems-antennas/ua860v-passive-omnidirectional-antenna

One can reasonably assume that the antenna has dimensions appreciably less than what one would expect for 1/4λ @ 174-216 MHz due to computer aided design with 3D NEC modeling of electromagnetic radiation patterns.  My guess is that Shure has much more advanced software than 4NEC2.   ;)  I have seen tech articles describing sub-1/4λ antenna designs for space systems' use that seem impossibly small, yet perform remarkably well.  Usually they're fractal or meander designs, so this may be irrelevant to this ground plane's geometry, but I can imagine that there might be something similar going on with the rounded diamond shape.  Then again, maybe not!

https://www.nasa.gov/centers/ames/news/releases/2004/04_55AR.html

https://www.nasa.gov/centers/ames/news/releases/2004/antenna/antenna.html

In the satellite there is quite a compelling reason to adjust the form factor.  Do any of these very complex designs perform even close to a reference dipole?

Prior to my stint at the Motorola wireless infrastructure group I worked in traditional land mobile systems design, paging to be specific.  The FCC required contours to be filed with your license that showed you protected other operators from interference.  The goal was always to get as close to another licensee as you could and we were very agresive with near field obstruction usage and various array configurations.  I forgot the mini we were using for simulation.  It was located at Arthur K. Peters and the runs would often take over a day to complete then be plotted on a pen plotter.   Arthur and David Carter were way ahead of the curve in software modeling.

Reason I bring all this up is I did a search and he is still using the software and has kept it updated.   Arthur has to be in his 80's now and was a pioneer in his field and it was an honor to work with him.

http://akpce.com/page8/page8.html

My point of all of this is the form factor reduction really worth the complexity and performance hit? 

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