Microwave Pulse Compression Experiments in a Waveguide Cavity with Breakdown Triggered Switch*
S. P. Savaidis, S. A. Mitilineos, Z. C. Ioannidis, N. A. Stathopoulos,
Department of Electronics Engineering, Technological Education Institute of Piraeus, GR 12244, Athens, Greece
SAVELEC (SAfe control of non cooperative Vehicles through ELECtromagnetic means) is a European research project that aims at stopping a vehicle by interfering with its Electronic Units (EUs), yet without any consequences on the passengers or any irreversible damage on the vehicle. Microwave pulse compression (MPC) systems are considered as a key element towards this goal, since they provide high-levels of generated power and a relatively wide spectrum that could efficiently affect vehicle’s EUs.
In the above mentioned context, a waveguide MPC system 1-3 that is formed by an inductive iris and an H-plane T-junction is experimentally studied. The design of the MPC waveguide cavity is based on the predictions of an equivalent circuit simulation model2-3 aiming to achieve a cavity extraction gain of 19 dB at 1.3 GHz. The switching trigger that implements the transition from the cavity storage to the cavity extraction state is implemented with a low pressure gas discharge tube (GTD) that is placed at the side arm of the T-junction. In this sense, the switching physical mechanism is based on RF breakdown phenomena, which inherently demonstrate stochastic behavior. Experimental results show that by carefully selecting the GTD gas type and pressure level, premature discharging is suppressed significantly and pulse compression statistics are optimized. Under optimal conditions the MPC system demonstrates an average cavity extraction gain close to the theoretically predicted and achieves a maximum pulse repetition frequency up to 150 Hz.
1. E. G. Farr, L. H. Bowen, W. D. Prather, and C. E. Baum, “Microwave pulse compression experiments at a low and high power,” Circuit and Electromagnetic System Design Notes - Note 63, Jan. 2010.
2. S. P. Savaidis; Z. C. Ioannidis, S. A. Mitilineos, N. A. Stathopoulos, "Design of Waveguide Microwave Pulse Compressors Using Equivalent Circuits," IEEE Trans. Microw. Theory Techn, Vol. 63, No. 1, pp. 125-134, Jan. 2015.
3. S. P. Savaidis, S. A. Mitilineos, N. A. Stathopoulos, Z. C. Ioannidis, "Modeling of a Waveguide Microwave Pulse Compression System using Transmission Line Theory and Equivalent Circuits", 2015 ICOPS, Belek, Turkey, May 2015.