Feasible diversity antenna design for dual band mobile handsets

Capacity improvements can be achieved in a CDMA cellular system through the use of handsets equipped with dual antennas/receivers. Signals received by each antenna are manipulated using various combining algorithms in the data processing in order to improve the overall received signal-to-interference-plus-noise ratio (RX SINR). The intent of this study is to demonstrate the feasibility of the diversity antenna design for existing commercial handsets and to evaluate the potential capacity improvements using field test data measured in a real cellular network. A feasible diversity antenna design is demonstrated on a dual band commercial handset. The selected platform, Qualcomm QCP-2700 handset, has an existing whip antenna. This antenna was considered as the primary antenna operating for transmit and receive. As secondary (receive only) antenna, a meander line inverted F antenna has been designed, implemented, and tested. A good rule of thumb derived from these results is to limit the average gain of the secondary (internal) antenna to be no less than 6 dB lower than that of the primary (external) antenna when the phone is in the talk position next to the user´s head. This was used as a performance goal for the design of diversity antennas.