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Audio Tips
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| Antenna Overview for Wireless Mics Part 2 |
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| December 11, 2007 |
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Previously, I described some types of antennas and simple physical mounting techniques for wireless microphone applications. In this article we will discuss more antenna mounting techniques and tips for general equipment placement.
When mounting multiple receive antennas, they should be separated by at least a quarter-wavelength in distance. For most VHF systems that would be about 16 inches, and for UHF the distance would only be about four inches. For diversity systems, performance is enhanced somewhat if these distances are increased towards one full wavelength.
With regard to antenna orientation, the receiving antenna should match the transmitting antenna. If the transmit antenna is vertically orientated, then the receive antenna should be as well. In cases where handheld mics can vary in orientation, a 45 degree mounted receive antenna is a workable solution.
Finally, as with most RF components, the closer the transmitter is to the receiver, the better. However, if metal racks or components are between the receiver and the transmitter, the system may benefit from a little increase in that distance to allow decreased interference in the path.
The path must also be kept clear of any obstructions that may absorb RF energy, including your audience. Mounting the receive antenna at least six feet above the floor helps eliminate RF absorption by the audience.
Most wireless microphone systems are delivered with proper instructions. However, often the instructions are not read completely, or do not cover the subject adequately. There are many resources available on the Web that can provide an in-depth explanation of the examples above.
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