User Manual

MM-018965-001
26
5.6.1 Antenna Requirements
There are several basic “types” of antennas. Each type has certain advantages and disadvantages for
particular applications in microwave and broadband wireless networks. Antennas and any associated
cabling which connects the antenna to the Broadband equipment comprise an “Antenna System.” In this
Antenna System all cable loss is subtracted from the antenna gain, the result being the Effective Antenna
System gain. Generally, the antenna system used with a VIDA Broadband device must meet the
following requirements:
Omnidirectional Antenna: Vertical or Horizontal Polarization
9 dBi Effective Maximum System Gain
Directional Antenna System: Linear Vertical or Horizontal
26 dBi Effective Maximum System Gain
(Reduction of Transmitter Power is required if the Effective Maximum
Antenna System Gain is greater than 26 dBi for 5 MHz operation or
29 dBi for 10 MHz operation.)
System antenna gain is defined as the antenna gain minus any cable or other losses between the base
station antenna port and the antenna.
NOTE
VIDA Broadband equipment is designed to use directional antennas with an antenna
system gain up to 26 dBi in a point-to-point or point-to-multipoint configuration.
In 5 MHz applications, the Transmitter Output Power must be reduced if the Effective
Antenna System Gain is greater than 26 dBi. The power reduction needs to be at least
equal to or greater than the amount the antenna system gain exceeds 26 dBi.
In 10 MHz applications, customers may use an Effective Maximum Antenna System Gain
up to 29 dBi before a power reduction is required. This is because of the Broadband
equipment’s self imposed 27 dBm maximum power; verses a permitted power of 30 dBm.
5.6.2 Antenna Types
The following paragraphs describe the different types of antennas that can be used with VIDA Broadband
devices. Table 5-2 contains a list of approved antennas. Detailed antenna descriptions can be found in
the VIDA Broadband Installation Manual, MM-014720-001.
Omnidirectional Antennas
An omnidirectional antenna is a vertical antenna. A vertical antenna’s radiation pattern or signal radiates
in all directions, losing power as the distance increases. Their radiation patterns are weaker directly
above or below the vertical plane. An omnidirectional antenna also picks up signals from all directions.
Grid Parabolic Antennas
The Grid parabolic antenna is a directional antenna that greatly reduces wind loading on a tower or other
mounting structures. Grid antennas have a lower front-to-back ratio than solid parabolic antennas. They
are also limited to a single polarization. They are ideal in applications where the best performance is not
required and tower and wind loading are the main concern.