1. Development and Operation of a Noise- Correlation Based Antenna Measurement System A Thesis by David A. Dieter Under the Supervision of Eric K. Walton and Advisement of Walter D. Burnside

2. February 23, 1978Born: East Cleveland, Ohio. 1996Diploma: Solon High School, Solon Ohio Graduation with Honors 1996Begin Undergraduate Work: The Ohio State University 1998 - 99Co-op: Ericsson, Research Triangle Park, North Carolina 1999Begin Research at the Electroscience Lab 2001Bachelor Degree: The Ohio State University with Honors and Distinction 2002Masters Degree: The Ohio State University [expected] VITA

3. Defense Presentation Overview Introduction System Theory Performance Issues Implementation Experimentation Measurement Setup and Results Conclusion QUESTIONS??

4. Introduction Noise Correlation Antenna Measurement System (NCAMS) Project Goal Key Step = Derivation of the Impulse Response Measure Success = Network Analyzer Data Comparisons Final Experimental Goal

5. Theoretical Approach * Use Noise Correlation, Find the System Impulse Response * Transform Time-Domain Response into Frequency-Domain Response Normalize System Response with AUT to System Response with Standard-Gain Antenna

6. Noise Correlation Device (NCD) NOISE TX N(t) R(t) N(t-  ) y(  ) N(t)RX h RX (t) LPF Entire System Impulse Response = h(t)

7. Impulse Response Explanation A cos(  1 *t) A 1 cos(  1 *t+  1 ) A 2 cos(  2 *t+  2 ) A 3 cos(  3 *t+  3 ) A 4 cos(   *t+   ) A cos(  2 *t) A cos(  3 *t) A cos(   *t) SystemSystem

8. NCD Derivation of Impulse Response N(t)h(t) Cross Correlation Delay =  N(t)  h(t) N(t -  ) h(  )  R NN (  ) …where R NN (t) is the autocorrelation of the noise

9. Frequency Domain Translation Fourier Transform = F { h(t)  R NN (t) } = H(f)  PSD(f) = H'(f) = Bandlimited Frequency Response

10. Normalizing Data Recall that h(t) is really a combination of many impulse responses h(t) = h rx (t)  h tx (t)  h cable (t)  h system (t) H'(f) = H' rx (f)  H' tx (f)  H' cable (f)  H' system (f)

11. Normalizing Data (cont'd) So if we perform the same measurement twice with different receive antennas... H1'(f) H' AUT (f)  H' tx (f)  H' cable (f)  H' system (f) H2'(f) H' stan (f)  H' tx (f)  H' cable (f)  H' system (f) H' AUT_relative (f) = H' AUT (f) / H' stan (f) H' AUT_absolute (f) = H' AUT_relative (f)  H' stan (f) = H' AUT (f) =

12. Theory Conclusions Noise correlation can determine the frequency response of an AUT normalized to a standard antenna The final normalized term is independent of the system response SO... we can use another measurement system to verify the NCAMS results

13. Performance Issues SNRo is same for any such device UWB noise systems are not susceptible to common interference problems Interfering energy is divided by Processing Gain G max = B / f c

14. Implementation Hardware = Ex-Noise Radar Performs Correlation as Explained Uses External and Variable Delay Operates 1.0 - 2.0GHz w/ fc = 10Hz Processing Gain = 80dB A/D Converter for Data Acquisition and Variable Delay Control RS-232 Serial Communication Port

15. Serially Controlled Variable Delay Can be adjusted in 12ps to any arbitrary delay value from: 0.0 to 31.75ns in 0.25ns steps 1 / 0.25ns = 4.0GHz = 2  2.0GHz Nyquist Theory Satisfied

16. Comments on Delay NCD can record an impulse response as long as all transients die within the 32ns variable delay window. Fixed delay coils are added in series with variable, to move impulse response into that window. Due to variable delay step, response must be bandlimited to 2.0GHz

17. Sample Impulse Waveform from NCD 0.0ns31.75ns nT (n *.025) V

18. Software Main Design Portion of Thesis Requirements All Signal Processing Done in One Package Provide Immediate Frequency-Domain Results Save, Plot, Recall, Print Options Intuitive / User Friendly Portable Labview (National Instruments)

20. Data Acquisition Process

21. Notable Program Items Simultaneous Display of up to three data scans to show repeatability Option of AUT, CAL, or AUT/CAL data display with one click "Save" option produces spreadsheet of data readable by Excel or Lotus Can be compiled to PC executable

22. Experimentation Three experiments performed to verify NCAMS data against Network Analyzer data Preliminary: Four antennas tested before software was developed Secondary: Approximation to Final Measurement Final: Azimuth Pattern of Auto-Antenna

23. Spectral Characteristics of NCD

24. Preliminary Experiment Setup

25. Preliminary Results

26. Preliminary Results (cont'd)

27. Secondary Experiment Build a model of antenna to be used on car in final experiment Test it under same conditions as final measurement without the rotating car Measure phase and magnitude and compare, again, to Network Analyzer

28. Car-Antenna Design Scheme Use tuning stub to set resonance

29. Secondary Experiment Setup

30. Secondary Experimental Results

31. Final Experiment Build loop antenna on car Rotate car and record data in 10 degree increments Plot gain pattern at antenna operating frequency Compare NCAMS and Network Analyzer data

32. Final Experimental Setup

33. Final Normalized Results

34. Final Absolute Results

35. Conclusion Noise Correlation can be used to measure complex frequency response of an AUT within decibels of the same network analyzer results It's suitable for outdoor measurements The usability of results may decrease as bandwidth of AUT decreases Dispersive Antennas?