Multilayer antennas with harmonic filtering for differentially fed power amplifier integration

In this study, a push-pull Class B configuration is used to demonstrate the fruitful use of a new proposed power combiner adopted from the previous aperture-coupled differential antenna structure. This structure differs from the previous aperture-coupled technique in that it comprises identical harmonic traps on either side of the aperture, using resonant stubs to form bandstop filters (BSF) whose residual susceptance at fundamental frequency is absorbed into the antenna matching network. The proposed design suppresses harmonic voltages at 2f_o and 3f_o, whilst also optimising the load line impedance seen by the two amplifiers at the fundamental frequency in odd mode at f_o (2.062 GHz). This technique offers advantages of tight integration of a Class B push-pull transmitting amplifier with an aperture fed antenna. It can produce well-shaped output waveform, enhance immunity from common mode interference and reduce the total loss as well as improve the overall efficiency for a wide range of system configurations.