SUMMARYThis paper reports the development of oscillators for low-power microwave transmission and also research on an oscillator array based on the newly developed oscillators. The oscillators have a simple configuration with an antenna directly connected to the output. For synchronization in an array, a new method is developed in which the oscillators are connected by band elimination filters (BEF) with specific phase characteristics. This structure is experimentally verified. The BEF used here has the characteristic of reflecting most of the generated signal while only a slight amount is leaked to other oscillators in an out-of-phase fashion. A locking experiment was performed with an oscillator array in which five oscillators are connected through BEF circuits, and the locking effect of the oscillators was observed. In addition, it was shown that the robustness to external disturbances and power supply voltage variations was improved.