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QUICK TIPS
The following tips are workarounds that can be used in situations where the proper accessories may not be readily
available. In most wireless microphone applications, there is rarely a single element that causes the whole system to fail,
but rather an aggregation of bad practices that leads to poor performance. With that in mind, employing one or two of
these "in a pinch" solutions is perfectly acceptable.
• For a remote antenna application when a 1/2-wave antenna is not available, a 1/4-wave antenna may be used,
as long as it is connected to an amplifier. Performance should be equal in effectiveness to a 1/2-wave antenna
remote-mounted with an amplifier.
• A 1/4-wave antenna can still be used in remote situations without an amplifier, but ONLY if a ground plane is
provided. The ground plane should be a metal surface that is at least 1/4-wavelength in diameter and grounded
to the BNC connector.
• Using 75-ohm cable is acceptable in remote antenna applications, and is more than likely less expensive than
50-ohm cable. Cable loss must still be taken into account.
• Antennas are designed to be sensitive to particular frequencies. Be sure to use the proper antenna for the
frequency of your wireless system. Antenna efficiency degrades somewhat outside of the designated frequency
range, but the slope is often gentle enough that the "wrong" antenna, if it is relatively close to the desired frequency
range, can be used with only minor attenuation of the RF signal. Note that VHF antennas should not be used for
UHF systems, and vice versa. Additionally, active antennas are strictly band-limited, and will not pass radio
frequencies outside of their specified frequency range.
• Dipole antennas designed for transmission of radio frequencies (as in wireless personal monitor systems), can
be used as receiver antennas (and vice versa), IF they are in the right frequency
passive directional transmitting antennas.
SUGGESTED READING
To learn more about antennas and wireless microphone applications, the following publications are highly
recommended:
The ARRL Antenna Book - 19th Edition
The National Association for Amateur Radio,
Newington, CT, 2000. ISBN: 0-87259-804-7
Selection and Operation of Wireless Microphone Systems
Tim Vear, Shure Incorporated, Niles, IL, 2003.
Wireless Systems Guide for
ANTENNA SETUP
The same holds true for
range.
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