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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Wireless and Communications => Topic started by: Keith Broughton on January 12, 2018, 05:44:55 am

Title: antenna isolation
Post by: Keith Broughton on January 12, 2018, 05:44:55 am
I have a number of RF mic situations where a Shure 1/2 wave antenna system will work fine.
I'm going to fabricate a mic stand adapter with a coaxial "pass through" connector on a small aluminum plate.
Considering this device will be connected to a metal mic stand or a truss, should the coax "pass through" be electrically isolated from the mounting plate?
I can think of a number of ways to do this so how it's done is not the question but rather, is it necessary.
Title: Re: antenna isolation
Post by: Jordan Wolf on January 12, 2018, 02:52:42 pm
Have you considered the bottom half of a broken mic clip?

Just fabricate a flange 90 to the mounting plate and pack it out with washers until it fits.
Title: Re: antenna isolation
Post by: Henry Cohen on January 12, 2018, 03:00:39 pm
I have a number of RF mic situations where a Shure 1/2 wave antenna system will work fine.
I'm going to fabricate a mic stand adapter with a coaxial "pass through" connector on a small aluminum plate.
Considering this device will be connected to a metal mic stand or a truss, should the coax "pass through" be electrically isolated from the mounting plate?
I can think of a number of ways to do this so how it's done is not the question but rather, is it necessary.

Although there are isolated bulkhead BNC female to female fittings, isolation is not necessary here.
Title: Re: antenna isolation
Post by: Keith Broughton on January 12, 2018, 03:03:36 pm
Have you considered the bottom half of a broken mic clip?

Just fabricate a flange 90 to the mounting plate and pack it out with washers until it fits.
While that is a great idea, that doesn't really answer the question.
Title: Re: antenna isolation
Post by: Keith Broughton on January 12, 2018, 03:04:03 pm
Although there are isolated bulkhead BNC female to female fittings, isolation is not necessary here.
Thanks Henry  :)
Title: Re: antenna isolation
Post by: Mike Caldwell on January 12, 2018, 07:26:18 pm
To get a couple 1/2 wave antennas up higher I used a dual mic mount bar.

Removing the two thumb screws that would be used to secure a mic clip two on each end left the perfect size hole to mount the BNC bulkhead connectors in.

 In the middle of the bar is a threaded hole to screw on a mic stand.

 I my case I use LO2B quick releases on just about all my stands so the female LO2B stays on the mic/antenna bar.
Title: Re: antenna isolation
Post by: Keith Broughton on January 12, 2018, 08:23:12 pm
To get a couple 1/2 wave antennas up higher I used a dual mic mount bar.

Removing the two thumb screws that would be used to secure a mic clip two on each end left the perfect size hole to mount the BNC bulkhead connectors in.

 In the middle of the bar is a threaded hole to screw on a mic stand.

 I my case I use LO2B quick releases on just about all my stands so the female LO2B stays on the mic/antenna bar.
A very good solution!
Still doesn't answer the question ;)
Title: Re: antenna isolation
Post by: Mike Caldwell on January 12, 2018, 08:33:36 pm
A very good solution!
Still doesn't answer the question ;)

Just saving you some time in the shop standing at the band saw and drill press!
Title: Re: antenna isolation
Post by: Debbie Dunkley on January 12, 2018, 09:34:55 pm
http://forums.prosoundweb.com/index.php/topic,165576.msg1529247.html#msg1529247
#85.

It works!!
Title: Re: antenna isolation
Post by: Jordan Wolf on January 12, 2018, 11:20:11 pm
While that is a great idea, that doesn't really answer the question.
How so?

The nylon/plastic clip would insulate the mounting adapter from the metal shaft of the mic stand.

Unless Im misunderstanding...
Title: Re: antenna isolation
Post by: Scott Helmke on January 12, 2018, 11:35:45 pm
I don't believe isolation is needed. If there's a connection to the mic stand it just means that the ground plane is bigger, which is not a problem. Without a connection the metal in the mic stand would cause the RF to behave in a less predictable fashion.