The haronics at the output is terminated especially to the second harmonic , in order to improve the output power and efficiency . we present a new method for harmonic tuning by using photonic bandgap ( pbg structure at the output of the power combiner in this thesis 我们在功率合成器的输出端使用二维微带pbg结构进行谐波调谐,用来提高合成器的输出功率。最后,讨论了功率合成中幅度、相位对合成效率的影响及系统的“适度恶化”现象。