Antenna connections

Use of a diversity antenna can improve system performance. It is required in 4G networks, but not 2G or 3G.

The following figure shows the SMA socket (female) antenna-connector locations.

1. Connect the cellular antenna to the Primary, Primary Antenna, or Antenna connector. Mount the cellular antenna so there is at least 20 cm between the antenna and the user or any bystander.

2. Connect a second antenna, if used, to the Diversity or Diversity Antenna connector.

Antenna diversity, also called space diversity, is a scheme that uses two or more antennas to improve the quality and reliability of a wireless link. Often, especially in urban and indoor environments, there is no clear line of sight between transmitter and receiver. Instead, the signal is reflected along multiple paths before finally being received. Each bounce can introduce phase shifts, time delays, attenuations, and distortions that can destructively interfere with one another at the aperture of the receiving antenna. Diversity-antenna-capable devices support multiple antennas (usually two) in order to combat this phenomenon and minimize its effects.

Diversity antennas are not required for 2G/3G connections; however, they are highly recommended in order to get the most reliable connection, especially in areas of low coverage. Identical or very similar antennas should also be used for the best results.

For 4G networks, the second antenna operates as a MISO (multiple-input, single-output ) antenna, providing a second receive path. This connection is required for operation on 4G/LTE networks.

Recommended antenna separation
Service	Frequency (MHz)	Wavelength (λ) (mm)	Best antenna separation (mm) (1/2 λ)	Good antenna separation (mm) (1/4 λ)
LTE	700	428	214	107
LTE	800	375	187	94
LTE	900	333	167	83
LTE	1800	167	83	42
LTE	2100	143	71	36
LTE	2600	115	58	29
WCDMA	850	353	176	88
WCDMA	900	333	167	83
WCDMA	1900	158	79	39
WCDMA	2100	143	71	36
CDMA/EV-DO	800	375	187	94
CDMA/EV-DO	1900	158	79	39
GSM/GPRS/EDGE	850	353	176	88
GSM/GPRS/EDGE	900	333	167	83
GSM/GPRS/EDGE	1800	167	83	42
GSM/GPRS/EDGE	1900	158	79	39

In more complex installations, such as those requiring long cable lengths or multiple connections, you must follow the maximum dBi gain guidelines specified by the radio communications regulations of the Federal Communications Commission (FCC), Industry Canada, ACMA in Australia, or your country's regulatory body.