Those antennas have a low pass filter built into them, that's the small S shaped traces on the board at the end of the main elements. That makes the antenna appear as a DC short to what ever it is connected to, depending on the equipment it is connected to that may or may not be an issue.
The biggest possible issue could be if the receiver or transmitter supplies DC power at the antenna jack for powering an inline RF amp.
I had some back-and-forth with Kent about his PCB antenna - a relevant reply to my question. Nice guy and answered my emails within 1/2 hour.
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Hi Frank
While they originally designed for EMI and Field Strength measurements, they have become quite popular in the Audio world. Also used in several Superbowls hunting for interference.
(Not everyone made sure their favorite frequency was open or even authorized)
Yes, they work well for transmit as well.
Diversity reception has been around since the 1930's. Basically you want the antennas to be at least a wavelength apart, or at different polarizations. For most wireless mics, this is about 2 feet.
Farther is nice if practical, especially if there are objects in the way. Or from a central area point one at the left of the stage and one to the right.
The only issue has been replacing active antennas with these. Some systems send a DC voltage up to the antenna to power a preamp. Most of our antennas are designed as a DC short. Someone walks across a thick carpet, touches the antenna, and ZAP there goes a few transistors. Making the antenna a DC short helps protect your equipment. Take a volt meter and put it at the end of your coax. Nothing? You're fine.
Got several DC volts? We have a little pigtail at the back of the antenna. Just cut it.
They can be painted black, or any other color. Just use enough paint to get the color you want and
avoid extra coats of paint.
Good luck with your project, Kent
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Also Kent noted that painting the antenna changes its tuning. I can't find it now, but it does not affect the performance in the wireless UHF range.