ProSoft Technology ILX34-AENWG - Manual (Page 72)

PSW-PWD ♦ ProSoft Software Antenna Selection Considerations
ProSoft Wireless Designer User Manual
Page 72 of 91
ProSoft Technology, Inc.
July 8, 2009
The antenna pattern is toroidal; its azimuth beam width is 360° (omnidirectional);
its vertical beam width depends on its length (the number of stacked elements),
such that more elements produce a narrower beam width.
The antenna gain, typically 5 to 10 dBi, also depends on the length (number of
stacked elements), such that more elements produce a higher gain.
The antenna polarity is linear, parallel to the length of the antenna.
8.2.2 Yagi Array Antenna
A Yagi antenna is composed of an array of linear elements, parallel to one
another and attached perpendicular to and along the length of a metal boom. The
feed is attached to only one of the elements. Elements on one side of the feed
element are longer and act as reflectors. Elements on the other side are shorter
and act as directors. This causes the antenna to radiate in a beam out the end
with the shorter elements. The actual pattern depends on the overall geometry,
including the number of elements, element spacing, element length, and so on.
In some cases, the antenna is enclosed in a protective tube that hides the actual
antenna geometry.
8.2.3 1/2 Straight Whip or 1/2 Articulating Whip
This is the most commonly used antenna type and does not require a ground
plane. These antennas are about 5 inches long and is typically connected to a
remote radio (directly to the enclosure).
The antenna pattern is a beam pointed along the boom toward the end with the
shorter elements. The beam width varies with antenna geometry but generally is
proportional to the length (where longer length produces a narrower beam).
The antenna gain, typically 6 to 15 dBi, also varies with antenna geometry, but is
generally proportional to the length (where longer length produces higher gain).
The antenna polarity is linear (parallel to the elements, perpendicular to the
boom).
An articulating antenna bends at the connection and functions the same as a
non-articulating antenna.
8.2.4 1/4 Whip Antenna
This antenna is about 2.5 inches long and does require a ground plane mounting
below the antenna and over the top surface of the radio. The 1/4 whip works well
with belt mounted radios but does not radiate well out the top of the antenna.
Because of this, it must remain vertical.