Theoretical and Experimental Study of Low-Loss, High- Efficiency Monolithic Antenna Structures at 94 GHz

Work was studied on power combining applications using coplanar waveguide (cpw)-fed slot antenna oscillators. In this work, a large amount of oscillators are combined together to result in a high power source. The problems encountered with such systems is the non-linear interaction in the coupled-oscillators. As a single oscillator, we use a slot-antenna with a single microwave transistor designed to oscillate at 20 0Hz. We have successfully combined a 2x2 array of these slot-antenna oscillators at 20 GHz to generate a total radiated power of 70 mW with a dc-RF efficiency of 15%. The power combining efficiency was 100%. Since the antennas are placed on a dielectric lens and therefore result in a high-gain pattern, the effective radiated power is around 4.5w. This configuration does not suffer from substrate mode problems and therefore can be easily extended to 94 GHz power combining systems. (MM)