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Author Topic: 1/2 wave antenna question (Shure)  (Read 764 times)

Matt Greiner

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1/2 wave antenna question (Shure)
« on: February 11, 2019, 11:56:41 pm »

Looking for some clarification/confirmation of my understanding of antenna's.

All antenna's have a frequency range/bandwidth, correct?  So as long as I use an antenna that is within the frequency range of my wireless receivers, I should be fine.  Even if the Shure website doesn't list them as compatible.

Here's my scenario -
I purchased a used UA844+, and I'm wanting to use (2) 1/2 wave antennas designed for a ULX system (518-598), since it has a larger frequency range than my SLX system.  The SLX systems are 542-572 and 572-596.  Shouldn't this setup work fine, even though the Shure website and literature do not confirm this?

Note - I would love to get some helical antenna's, but for the gigs I do, they would be overkill (and overbudget).

Thanks in advance!
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Luke Geis

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Re: 1/2 wave antenna question (Shure)
« Reply #1 on: February 12, 2019, 02:05:01 am »

If the frequency bandwidth of the antenna is larger the needed bandwidth for your radio's, then you will be fine.
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Keith Broughton

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Re: 1/2 wave antenna question (Shure)
« Reply #2 on: February 12, 2019, 06:33:49 am »

As Luke indicated, the 518-598 antennas will work fine.
As for helicals, or paddles, if the application doesn't require those tools, buying them is just an added expense.
Remember to keep "line of sight" as a rule. With 1/2 wave, you can extend the coax and raise them up on a stand, if needed.
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Scott Helmke

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Re: 1/2 wave antenna question (Shure)
« Reply #3 on: February 12, 2019, 08:38:14 am »

The frequency range for those antennas isn't hard limited to those frequencies, too.  There's a fairly gentle slope down beyond the listed range.
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Matt Greiner

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Re: 1/2 wave antenna question (Shure)
« Reply #4 on: February 12, 2019, 11:13:31 pm »

As Luke indicated, the 518-598 antennas will work fine.
As for helicals, or paddles, if the application doesn't require those tools, buying them is just an added expense.
Remember to keep "line of sight" as a rule. With 1/2 wave, you can extend the coax and raise them up on a stand, if needed.

Thank you Keith and Luke.  You confirmed my initial thoughts.

The frequency range for those antennas isn't hard limited to those frequencies, too.  There's a fairly gentle slope down beyond the listed range.

Also very good information to know.  Thanks everyone!
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Loren Miller

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Re: 1/2 wave antenna question (Shure)
« Reply #5 on: February 15, 2019, 04:59:21 pm »

As Luke indicated, the 518-598 antennas will work fine.
As for helicals, or paddles, if the application doesn't require those tools, buying them is just an added expense.
Remember to keep "line of sight" as a rule. With 1/2 wave, you can extend the coax and raise them up on a stand, if needed.

Antennas on a stand, the best and most effective $30 I have spent!!!
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Dave Garoutte

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Re: 1/2 wave antenna question (Shure)
« Reply #6 on: February 15, 2019, 07:48:31 pm »

So real newbie antenna question:
What is the advantage / disadvantage of 1/2 wave over 1/4 wave?
What does mounting either of those on a stand look like?
Do they need to be mounted on a plate?
So many questions . . .
I have a set of paddles, but may need more options in the future.
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Russell Ault

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Re: 1/2 wave antenna question (Shure)
« Reply #7 on: February 15, 2019, 08:22:03 pm »

So real newbie antenna question:
What is the advantage / disadvantage of 1/2 wave over 1/4 wave?
What does mounting either of those on a stand look like?
Do they need to be mounted on a plate?

When we talk about a half-wave antenna, we are typically talking about a "dipole" antenna. If you were to remove the plastic jacket on most half-wave antennas, you'd find two separate equal-length elements inside, each half the length of the antenna. Electrically, connection to these elements is made at the centre of the antenna (even if the BNC connector is on the bottom). These two opposing elements make a dipole a complete antenna design that can do its job all on its own.

For all sorts of physics reasons, a dipole can often be thought of as the default antenna design (so much so that other antenna designs are sometimes described in relation to how a dipole would perform; this even has its own decibel unit of dBd). Most paddle antennas (but not helicals) are variations on the basic dipole (the D in LPDA stands for Dipole).

A quarter-wave antenna is, arguably, a bit of a hack. If you remove half of a half-wave dipole, what you're left with is a quarter-wave antenna. You have a single element that is end-connected. This is really only half an antenna—and if you suspend it in mid air at the end of a cable it will likely perform very poorly—but we can simulate the other half of the antenna by providing a ground plane. A piece of metal connected to RF ground near the quarter-wave antenna's connect point emulates (with some efficiency loss) the missing half of the dipole, and creates a complete antenna. In a pinch, if you need to get a quarter-wave antenna up in the air, you can supply the other half of the antenna in the form of a counterpoise, which can be as simple as a piece of wire hanging down from the antenna and tied electrically to RF ground at its base.

-Russ;

(Edited to fix a ridiculous number of typos.)
« Last Edit: February 17, 2019, 03:04:09 am by Russell Ault »
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brian maddox

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Re: 1/2 wave antenna question (Shure)
« Reply #8 on: February 15, 2019, 08:25:33 pm »

When we talk about half-wave antennas, we are typically talking about a "dipole" antenna. If you were to remove the plastic jacket on most half-wave antennas, you'd find two separate equal-length elements inside, each half the length of the antenna. Electrically, connection to these elements are made at the centre of the antenna (even if the BNC connector is on the bottom). These two opposing elements make dipoles complete antennas that can do their job all on their own.

For all sorts of physics reasons, a dipole can often be thought of as the default antenna designs  (so much so that other antenna designs are sometimes described in relation to how a dipole would perform; this even has it's own decibel unit of dBd). Most paddle antennas (but not helicals) are variations on the basic dipole (the D in LPDA stands for Dipole).

A quarter-wave antenna is, arguably, a bit of a hack. If you remove half of a half-wave dipole, what you're left with is a quarter-wave antenna. You have a single element that is end-fed. This is really only half an antenna, and if you suspend it in mid air at the end of a cable it will likely perform very poorly, but we can simulate the other half of the antenna by providing a ground plane. A piece of metal connected to RF ground near the quarter-wave antenna emulates (with some efficiency loss) the missing half of the dipole, and creates a complete antenna. In a pinch, if you need to get a quarter-wave antenna up in the air, you can supply the other half of the antenna in the form of a counterpoise, which can be as simple as a piece of wire hanging down from the antenna and ties electrically to RF ground at its base.

-Russ

Such great info.  Helped to fill in some gaps in my knowledge base, which i always appreciate.
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Keith Broughton

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Re: 1/2 wave antenna question (Shure)
« Reply #9 on: February 15, 2019, 09:52:59 pm »

So real newbie antenna question:
What is the advantage / disadvantage of 1/2 wave over 1/4 wave?
What does mounting either of those on a stand look like?
Do they need to be mounted on a plate?
So many questions . . .
I have a set of paddles, but may need more options in the future.
The quick and easy answer is 1/2 wave needs no "plate" or ground plane when mounted in the air. Easier to deal with.
1/4 wave antennas need a ground plane.

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