Diversity Antenna

[gkuma]

Anyone know where I can find requirements for a diversity antenna for a cell phone? Like how many dB should the LB and HB differ from the primary antenna? Is there a set of rules for this?

 

[Higgler]

usually diversity antennas are nearly identical (more than one identical per band) and separated by distance or orientation.

Separations of as much as possible (on your platform) is preferred to enable each antenna to be designed independently and avoid mutual coupling.

 

[Comcokid]

In North America, cell phone performance standards and test specifications are organized by PTCRB.org for GSM cellular and CDG.org for CDMA cellular. Each of the cellular carriers may add a few additional requirements for a phone specifically qualified for their network.

Within these organizational standards are peformance requirements of the cellular antennas over the bands and the ratio of horzontal and vertical polarization.

I'm not well familiar with the requirements, but I'm not aware of provisions for diversity antennas on the cell phone or other mobil device.

 

[gkuma]

What about a LTE-MIMO application?

I understand the diversity antenna is similar to the primary maybe not having as much bandwidth in the bands or efficiency. But looking at a gain standpoint(S21), should the diversity antenna be within 2dB of the primary antenna at least at some point in the bands?

I have read that "Diversity Gain should be close to 10dB" but I realize that takes into account the correlation and SNR ratio? So I believe those are two different things. Am i right?

Have there been standards set for this or is it in the process or carrier by carrier specific?

Thanks for your help.

 

[Higgler]

I searched on "diversity gain should be close to 10 dB" and found

It is shown that the statistical distributions follow the Rayleigh curve and hence a diversity gain close to 10 dB can be obtained for an availability of 99%.

This gain mentioned has nothing to do with an antenna gain being within 10 dB of the primary antenna. It's a net effective gain based on system bandwidth.

Hence your answer is, make all the antennas good, not one good and one degraded.