ZTE Corporation ZM8300G Manuale Utente
ZTE ZM8300G Module Hardware User Manual
<All rights reserved. No distribution without prior permission of ZTE.>
42
clearance area is an area without metal. A large clearance area indicates high antenna
efficiency. If an RF output port is connected to the input port of an antenna using a cable, the
loss caused by the cable needs to be considered. Generally, the loss caused by a cable is
proportional to the cable length and frequency. Therefore, use short cables if possible. To
enable a ZM8300G module to obtain better RF radiation performance, it is recommended that
the antenna efficiency be greater than 45% (within all frequency bands).
4.4.3
VSWR
When a feeder does not match an antenna, an incident wave and a reflected wave co-exist in
the feeder. For the in-phase position of the two waves, the amplitude has maximum value,
and an antinode is formed. For the reverse-phase position of the two waves, the amplitude
has minimum value, and a wave node is formed. The amplitudes at other points are between
the antinode and the wave node. Such a combined wave is called a standing wave. The ratio
of the voltage at an antinode of a standing wave to the voltage at a node of the standing wave
is called the voltage standing wave ratio (VSWR). A small VSWR indicates better antenna
performance. The VSWR of an antenna can be measured using a vector network analyzer.
For the ZM8300G module, it is recommended that the VSWR be less than 3.0.
4.4.4
S11
The S11 indicates the transmit efficiency of an antenna. A large S11 indicates more returned
power and poor antenna efficiency. The S11 can be measured using a vector network
analyzer. For the ZM8300G module, it is recommended that the S11 be less than -8 dB.
4.4.5
Polarization
The antenna polarization is a parameter used to describe the spatial orientation of the
antenna-radiated electromagnetic field vector. As the electric field has a constant relationship
with the magnetic field, the spatial orientation of the electric field vector is generally used as
the polarization direction of antenna-radiated electromagnetic waves. Generally, linear
polarization, circular polarization, and elliptical polarization are available. For the ZM8300G
module, linear polarization is recommended for its antennas.
4.4.6
Radiation Pattern
The radiation pattern describes the distribution of antenna radiation in space, especially the
distribution in the far field region, and indicates the characteristics of a field, for example, the
product of the size/field strength and the distance, radiant intensity, directivity, absolute gain,
and relative gain of a specified component of the electromagnetic field.
Since the incident wave of a base station is horizontal, a wireless terminal has optimal
reception performance when the radiation pattern of its receive antenna is omni-directional in
the horizontal plane. For the ZM8300G module, omni-directional radiation pattern is
recommended for its antennas.