Shure WA490 User manual

MODEL WA490 HALF–WAVE ANTENNA FOR
WIRELESS MICROPHONE APPLICATIONS
The Shure Model WA490 is a half-wave wireless micro-
phone antenna that provides up to 3 dB more gain than the
standard quarter-wave antennas supplied with Shure wire-
less microphone receivers. A low–cost alternative to con-
ventional telescoping half-wave antennas, the WA490 of-
fers the additional advantages of ruggedness and the
capability for unobtrusive wall- or ceiling-mounting in or
around the operating area. When locating the antenna at
a distance from the receiver, a half-wave antenna such as
the WA490 must be always be used instead ofthe standard
quarter-wave antenna.
This WA490 consists of a small molded plastic housing
with two mounting flanges molded into its body (see Figure
1). One end of the housing contains a short length of
RG–174/U coaxial cable terminated in a female UHF coaxial
connector for connection to the wireless receiver antenna in-
put through an extension cable (Shure WA421: 6.1 me-
ters—20 feet, or equivalent). The other end of the housing
contains a length of 300 Ωtwin-lead wire, cut to a length that
matches the wireless frequency range in use.
NOTE: Diversity receivers require two WA490 antennas.
When both antennas are remotely located, each must use
an extension cable.
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76.2 mm (3 in.)See text
21.4 mm (27/32 in.)
50.8 mm
OVERALLDIMENSIONS
FIGURE 1
(2 in.)
300 TWIN LEADΩ
UHF
CONNECTOR
Selecting the Proper Antenna
The WA490 is available in three configurations, which cor-
respond to three frequency bands, as follows:
MODEL FREQUENCY
RANGE APPROXIMATE LENGTH
WA490A 169 to 185 MHz 1.13 m (441/2in.)
WA490B 185 to 200 MHz 1.04 m (41 in.)
WA490C 200 to 216 MHz 0.95 m (3717/32 in.)
For best performance, choose the antenna that corre-
sponds to your system’s operating frequency. If you are us-
ing the WA490 with an antenna distribution system such as
Shure’s Model WA405, select the antennas as follows:
SIf the frequencies are all in the same band, select the an-
tennas for that band.
SIf the frequencies span two adjacent bands, select anten-
nas for the lower frequency band.
SIf the frequencies span all three bands, use one WA490A
antenna and one WA490C antenna.
Installing the WA490
For best results with diversity receivers, the receiver anten-
nas must be separated by at least one wavelength (1.5 me-
ters—60 inches) or more.
Study the area in which the wireless microphone system is
to be used. Locate an optimum wall or ceiling surface that
will provide continuous line-of-sight contact between the
transmitter and the WA490. While the WA490 can be easily
removed for use in other locations, it is most readily used in
permanent or semi-permanent installations. Mount the
WA490 using the two mounting flange holes (3.81
mm—0.150 in. diameter) and the eyelet hole (3.18
mm—0.125 in. diameter). The type of mounting hardware
used depends on the mounting surface. If desired, the
WA490 can be painted or otherwise disguised after mount-
ing (non-metallic covering).
The WA490 can also be fastened to wooden beams, scen-
ery flats, curtains, or to the rear (away from the audience) of
lecterns or altars (Figure 2).
IMPORTANT: Avoid mounting the WA490s along metal
beams or metal-studded walls; the antennas must always be
well away from any metallic object or surface, and always
within the transmitter line of sight.
LECTERN MOUNTING
FIGURE 2
Model WA490 User Guide
27C8407 (Rev. 4)
2001, Shure Incorporated Printed in U.S.A.
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