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Amplifier-Based Active Antenna Oscillator Design at 0.9-1.8 GHz

Amplifier-Based Active Antenna Oscillator Design at 0.9-1.8 GHz. Isaac Waldron, Ayoob Ahmed, & Sergey Makarov Worcester Polytechnic Institute ECE Department Worcester, MA 01609. Outline. Motivation Oscillator Design Performance Conclusion. Motivation.

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Amplifier-Based Active Antenna Oscillator Design at 0.9-1.8 GHz

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  1. Amplifier-Based Active Antenna Oscillator Design at 0.9-1.8 GHz Isaac Waldron, Ayoob Ahmed, & Sergey Makarov Worcester Polytechnic Institute ECE Department Worcester, MA 01609 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  2. Outline • Motivation • Oscillator Design • Performance • Conclusion 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  3. Motivation Self-directed project to design an active antenna using a commercial off-the-shelf RF amplifier IC. 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  4. Antenna Geometry 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  5. 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 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  6. 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. 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  7. Typical Antenna Setup 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  8. Spectrum 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  9. 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. 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  10. Phase Noise 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  11. Bias Tuning 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  12. Co-polar Radiation Pattern 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  13. 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. 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  14. Antenna Tuning 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

  15. Conclusion • Oscillator designed from open-loop transmission. • Prototypes match predicted oscillation frequency. • Bias and geometric tuning were demonstrated. • Regions of operation were determined. 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics

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