The development of integrated antennas for LINC transmitters

Five integrated antennas recently developed for LINC (linear amplification using nonlinear components) radio transmitters are presented. In addition to its original function as a radiator, the integrated antenna can also fulfil the function of a power combiner, thus ensuring maximum power efficiency. This would be useful for current LINC, where the circuit-level power combiner losses degrade overall efficiency. The concept is explained and the results of several integrated antennas are illustrated and discussed. It is shown that the integrated antenna can achieve good impedance matching under both even- and odd-mode excitation. Effective suppression of radiation patterns under the unwanted even-mode (or odd-mode) excitation is also achieved.