•
The metal element may absorb the antenna radiated power and produce a certain
amount of secondary radiation, and coupling frequency is associated with the size
of metal parts. Therefore, this kind of component should have a good grounding to
eliminate or reduce secondary radiation.
6.9. Diversity and MIMO Antenna Design
•
Diversity receiving technology is a main anti fading technology, which can greatly
improve the transmission reliability in multipath fading channels. Its essence is to
use two or more different methods to receive the same signal to overcome the
fading and improve the receiving performance of the system.
•
Diversity antenna can also multiplex different transmission paths in space using
division multiplexing technology and receive data from the multiple different paths
in parallel to improve the receiving throughput.
•
The function of MIMO antenna is similar to that of diversity antenna, and they both
can resist against fading and improve throughput.
•
The customer is recommended to design the corresponding antenna according to
the antenna requirements of each module antenna port.
•
The design method of diversity antenna and MIMO antenna is consistent with that
of main antenna. It is recommended to control the difference of the efficiency of
diversity antenna and MIMO antenna from that of main antenna by no more than
3dB.
•
The isolation of each antenna shall be greater than 25dB, and the antenna
correlation coefficient shall be less than 0.5. High isolation does not mean good
correlation coefficient. Customers need to evaluate two indexes separately. The
isolation and correlation coefficient of antenna generally depend on:
◦
Antenna isolation
◦
Antenna type
◦
Antenna directivity
6. Radio Frequency
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