1. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation1 Mixing Behavior of a Dual-Patch Active Antenna Oscillator at 1.2 GHz Isaac Waldron* & Sergey Makarov Worcester Polytechnic Institute ECE Department Worcester, MA 01609

2. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation2 Outline Motivation Oscillating Antenna Design Mixer Behavior of Active Oscillator Experimental Results Mixing Model of Antenna Amplifier Conclusion

3. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation3 Motivation Follows work by Prof. Makarov and myself on the design of an amplifier-based active antenna oscillator. Investigates the mixing behavior exhibited by the antennas of that work.

4. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation4 Oscillating Antenna Design

5. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation5 Oscillator Linear Model Oscillation prediction follows from Berkhausen criteria: 1 - A(s)H(s) = 0 or |A(s)H(s)| = 1,  A(s)H(s) = 0 

6. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation6 Oscillator Open-Loop Response The antenna will start to oscillate at approximately the frequency marked by the diamond; at this frequency, a signal traveling around the loop returns in phase.

7. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation7 Typical Antenna Setup

8. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation8 Spectrum

9. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation9 Locking Bandwidth Locking bandwidth of about 100 kHz on each side of the center frequency was observed. Holding bandwidth of about 200 kHz on each side of the center frequency was observed.

10. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation10 Phase Noise

11. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation11 Bias Tuning

12. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation12 Co-polar Radiation Pattern

13. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation13 Antenna Tuning The oscillation frequency of the antenna linearly depends on the leading patch dimension. It also depends on the ratio between the width and length of the patches. Below a certain patch length, oscillations in the desired mode cease as the coupling between the antenna ports drops below a critical value.

14. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation14 Antenna Tuning

15. July 3-8, 2005, Washington DC 2005 AP-S International Symposium on Antennas and Propagation15 Conclusion Oscillator designed from open-loop transmission. Prototypes match predicted oscillation frequency. Bias and geometric tuning were demonstrated. Regions of operation were determined.