Feedback optimization of grid oscillators

We present a method for optimizing the feedback level in a transistor-grid oscillator. Based on the approximate large-signal S-parameters of the transistor, an equivalent circuit model for the grid is synthesized for maximum oscillator power. The resulting circuit serves as a convenient benchmark for determining the level of feedback for a given grid. Experimental results demonstrate how the substrate thickness and metallization pattern affect power performance. A grid with an asymmetric unit cell is shown to deliver almost 60% more effective radiated power than a grid with a symmetric unit cell.