Transistor oscillator and amplifier grids

In this paper, we review recent developments in quasi-optical power combining. In particular, we examine planar periodic grids and their use as quasi-optical active components. A variety ofgrids used for the generation and amplification of electromagnetic radiation have been investigated. Although quasi-optical techniques are applicable to a large variety of solid-state devices, special attention is given to transistors. Transistors are attractive because they can be used as either amplifiers or oscillators. Experimental results for MESFET bar-grid and planar grid oscillators are presented. In addition, we discuss a MESFET grid amplifier that receives only vertically polarized waves at the input and radiates horizontally polarized waves at the output. An advantage of these planar grids is they can be scaled for operation at millimeter- and submillimeter-wave frequencies. By using modern Ie fabrication technology, planar grid oscillators and amplifiers containing thousands of devices can be built, thereby realizing an efficient means for large-scale power combining.