April 3-7, 2005, Honolulu, HI 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied...
15
April 3-7, 200 5, Honolulu, H I 2005 IEEE/ACES Int'l Conference on Wireless Commu nications and Applied Computational Electromagnet ics 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
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Transcript of April 3-7, 2005, Honolulu, HI 2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied...
April 3-7, 2005, Honolulu, HI
2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics
1
Amplifier-Based Active Antenna Oscillator Design
at 0.9-1.8 GHzIsaac Waldron, Ayoob Ahmed, & Sergey
MakarovWorcester Polytechnic Institute
ECE DepartmentWorcester, MA 01609
April 3-7, 2005, Honolulu, HI
2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics
2
Outline
• Motivation• Oscillator Design• Performance• Conclusion
April 3-7, 2005, Honolulu, HI
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.
April 3-7, 2005, Honolulu, HI
2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics
4
Antenna Geometry
April 3-7, 2005, Honolulu, HI
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) = 0or
|A(s)H(s)| = 1, A(s)H(s) = 0
April 3-7, 2005, Honolulu, HI
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.
April 3-7, 2005, Honolulu, HI
2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics
7
Typical Antenna Setup
April 3-7, 2005, Honolulu, HI
2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics
8
Spectrum
April 3-7, 2005, Honolulu, HI
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.
April 3-7, 2005, Honolulu, HI
2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics
10
Phase Noise
April 3-7, 2005, Honolulu, HI
2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics
11
Bias Tuning
April 3-7, 2005, Honolulu, HI
2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics
12
Co-polar Radiation Pattern
April 3-7, 2005, Honolulu, HI
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.
April 3-7, 2005, Honolulu, HI
2005 IEEE/ACES Int'l Conference on Wireless Communications and Applied Computational Electromagnetics
14
Antenna Tuning
April 3-7, 2005, Honolulu, HI
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.
