PA calibration in TDMA antenna arrays

The behavior of a 5.2-GHz transmit antenna array in time division multiple acess operation is investigated, where the power amplifiers are only switched on during the data bursts. Using monolithically integrated power amplifiers, two thermal time-constants are found, associated with gain and phase changes that alter the antenna pattern. In this letter, the correlation of these changes between multiple channels is experimentally studied to derive guidelines for the calibration of such an array. It is found that changes within the typical burst duration are well correlated and no time-dependent calibration is needed. Thermal changes linked to a second time-constant lead to a calibration error.