User's Manual

ANTENNAS
TYPES OF FIXED ANTENNAS
ENVOY™ TRANSCEIVER REFERENCE MANUAL 395
Types of fixed antennas
Vertical whip antenna
Description
The vertical whip antenna is omnidirectional in performance, therefore it provides
radiation efficiency equally in all directions depending on its mounting position.
When receiving, this omnidirectional performance may mean more unwanted signals
are picked up, which contributes to high levels of background noise or interference.
Where used
The vertical whip antenna is designed for installation on buildings or open ground.
The antenna is suitable for most transceivers operating with an antenna tuner.
Installation
The vertical whip antenna is designed for permanent or temporary installation. The
antenna is easy to install.
For efficient operation of the vertical whip antenna, a good earth system is necessary.
When the antenna is erected on open ground, especially in dry ground conditions, an
earth mat consisting of at least four wire radials extending as far as possible from the
base is desirable.
For roof-mounted installations, metal roofing or a radial earth plane is recommended.
Advantages and limitations
Table 42: Advantages and limitations of the vertical whip antenna
Advantages Limitations
Suitable for long-distance
communication.
Omnidirectional antenna, therefore it
can pick up signals equally in all
directions.
Suitable where space is limited.
Unsuitable for communication
distances under 100 km (60 mi).
This antenna is more susceptible to
noise pickup such as that produced by
welders, electric motors, power lines
etc. If installed in a noisy environment,
the received signal is degraded.
Due to its relatively small size, it may
require an antenna tuner for optimum
performance.