Shure WL83 Spezifikationen PDF herunterladen (Seite 14)

ANTENNAS

TRANSMITTER

The transmitter antenna is a permanently attached,

flexible wire, 1/4-wave antenna. It has an omnidirectional

transmission pattern (equally effective in all directions)

and is designed to operate in a vertically polarized mode.

This means that the antenna should hang downward dur-

ing operation; coiling or wadding it to minimize visibility

will reduce the system’s operating distance.

RECEIVER

The receiver antennas are three-section, 5/8-wave

whip antennas approximately 762 mm (30 in.) for 176 to

216 MHz operating frequencies, or 991 mm (39 in.) for 150

to 176 MHz. Like the transmitter antenna, the receiver

antennas have an omnidirectional pickup pattern and

are vertically polarized. Vertical mounting of both anten-

nas is a requirement for optimum pickup.

The receiver antenna’s three sections must be joined

for optimum reception. One or two antenna sections will

result in reduced distance capability.

The receiver antennas are supplied with one right-

angle UHF adapter for connecting one antenna to the

receiver, a 7.6m (25 ft) coaxial cable (WA280) with UHF

connectors for attaching the remotely located antenna

to the receiver, and a wall-mount bracket (WA260) with

hardware for mounting the remote antenna to a wall,

cabinet, etc.

Receiver Antenna Distance

For optimum performance of the DIVERSIPHASE™

system, proper antenna spacing is extremely important.

NEVER mount both antennas directly to the receiver

connectors. A minimum of 1.8m (6 ft) between antennas

is required for effective diversity reception (see Figure 7).

The 7.6m (25 ft) coaxial cable supplied with the anten-

nas will provide “optimum” spacing between antennas

of 6.1-7.6m (20-25 ft) under ideal conditions. This, of

course, means little or no interference or reflections and

constant line-of-sight transmission.

•

Unfortunately, the real world is not free of these prob-

lems, and some applications may require greater anten-

na spacing for good diversity reception. An additional

7.6m (25 ft) coaxial cable (WA280) will provide 15.2m (50

ft) spacing and decreased problems. If greater lengths

are needed, the use of heavy-duty coaxial cable (Belden

8214 or equivalent) can be used for a maximum of 30m

(100 ft).

RECEIVER-TRANSMITTER DISTANCE

Observing the following rules regarding transmitter to

receiver antenna distance will yield the best results

possible.

ANTENNA SPACING

FIGURE 7

Keep the transmitter to receiver antenna distance as

short as possible. As the distance increases, the

transmitted signal is weaker (see Figure 8).

Make certain the signal path between the transmitter

and the receiver antennas is unobstructed. The

transmitter wearer should be able to visually locate

at least one receiver antenna at any time (see Figure

9).

Try to avoid operating the system through or around

walls, ceilings, metal objects, etc. The usual result is

reduced range and performance, and the signal

reflections off metal obstructions will not only cause

reduced signal, but will introduce the problem of

multipath distortion (see Figure 10).

Receiver Antenna Mounting

The remotely located receiver antenna can be

mounted in a variety of locations and using a variety of

mounting methods. The supplied wall mount bracket

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