Wireless Question regarding Log-Periodic Dipole Array/ Sharkfin
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BNBSound
Active Member
Unless you're right at the fringe of reception or in an incredibly dense RF environment like a football stadium in a large city you don't need two. The receivers these days are diversity which means there are two in each box and a circuit votes on which one to use. If one antenna is a paddle and the other is a 1/4 or 1/8 wave rubber duck then the paddle wins all the time. If your receivers are only a hundred feet from the stage you shouldn't ever have a problem running a system like that and you can save $250 or so to buy something else.
The only time I'd ever use one LPDA and one whip would be if the second LPDA got broken or fell out of the truck.
Diversity was designed to work best when the signal levels are similar.
In many ways, it would be like having 2 microphones on a speaker - one a condenser mic (the LPDA) and one a SingStar Karaoke mic (the whip) and trying to mix the two - all the while while the presenter is moving about and dropping in and out of the lobes of the condenser's coverage pattern.
There is a company (and right now I can't remember their name) who are making a combination LPDA and dipole in the same assembly. This gives you polarisation diversity which in many cases is as good and in some cases better than the spatial diversity normally used with LPDAs. It comes with 2 connectors on the bottom for 2 coaxes to connect.
One however MUST remember that LPDAs are a tool, and one that can be used wrong just as easily as they can be used right.
There are some situations where they are absolutely the wrong tool to use and stock whips will give much better performance.
Oh and you would only use at most ONE LPDA per system if it's the transmit antenna for an IEM rig... (Noting that multiple antennas, appropriately spaced, can easily outperform using combiners to sum multiple IEMs together. Again an area where you need to understand ach tool's characteristics and how to use it properly...
Diversity was designed to work best when the signal levels are similar.
In many ways, it would be like having 2 microphones on a speaker - one a condenser mic (the LPDA) and one a SingStar Karaoke mic (the whip) and trying to mix the two - all the while while the presenter is moving about and dropping in and out of the lobes of the condenser's coverage pattern.
There is a company (and right now I can't remember their name) who are making a combination LPDA and dipole in the same assembly. This gives you polarisation diversity which in many cases is as good and in some cases better than the spatial diversity normally used with LPDAs. It comes with 2 connectors on the bottom for 2 coaxes to connect.
One however MUST remember that LPDAs are a tool, and one that can be used wrong just as easily as they can be used right.
There are some situations where they are absolutely the wrong tool to use and stock whips will give much better performance.
Oh and you would only use at most ONE LPDA per system if it's the transmit antenna for an IEM rig... (Noting that multiple antennas, appropriately spaced, can easily outperform using combiners to sum multiple IEMs together. Again an area where you need to understand ach tool's characteristics and how to use it properly...
That's the one I was thinking of...
Short answer: yes, it will work with a single antenna. How well? Hard to say!
Longer answer: Just like sound waves, radio waves reflect off of surfaces in a venue, creating a pattern of peaks and nulls. This pattern is constantly in flux as actors walk around a stage. As a result, your single antenna could end up in one of those nulls, leading to a dropout.
The common solution to the problem is to use a pair of similar antennas, spaced apart, to reduce the odds of ending up in a null. There are other ways to do it (e.g., the Diversity Fin antenna), but they all work about the same.
Longer answer: Just like sound waves, radio waves reflect off of surfaces in a venue, creating a pattern of peaks and nulls. This pattern is constantly in flux as actors walk around a stage. As a result, your single antenna could end up in one of those nulls, leading to a dropout.
The common solution to the problem is to use a pair of similar antennas, spaced apart, to reduce the odds of ending up in a null. There are other ways to do it (e.g., the Diversity Fin antenna), but they all work about the same.
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