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RF Testbed for TCT D Fallon - Electronics Research Inc L Yan, G Hanson, S Patch - UWM

RF Testbed for TCT D Fallon - Electronics Research Inc L Yan, G Hanson, S Patch - UWM. uncontrolled E-field & loss. ~10ns. Feng et al ‘01. Wisc ‘07. Goal - controlled illumination for large FOV imaging. optimized match. ?match?.

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RF Testbed for TCT D Fallon - Electronics Research Inc L Yan, G Hanson, S Patch - UWM

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  1. RF Testbed for TCTD Fallon - Electronics Research IncL Yan, G Hanson, S Patch - UWM

  2. uncontrolled E-field & loss ~10ns Feng et al ‘01 Wisc ‘07 Goal - controlled illumination for large FOV imaging optimized match ?match? • illuminate with high-power, broadband (short) pulse w/108 MHz carrier freq • control polarization of E field • quantify • Pinc, both power and envelope • Ptrans, • Pinc - Ptrans - Pbaseline = power loss in object

  3. thermal TCT Wave Eq Model mechanical electrical + homog ICs for I(t)= (t)

  4. Quantitative Imaging Challenges • partial scan data - iterative recon • transducer aperture size - integrating detectors • acoustic attenuation - corr. for aphysical model • variable soundspeed • E field pattern/optical fluence corr. • broadband data required, including low freqs • unwanted EM coupling to US measurements • transducer response - freq dependent & has limited sensitivity - anisotropic

  5. E-field pattern & Acoustic Source SOP to solve in frequency domain near carrier frequency. Solve Helmholtz in frequency domain • 1) E is wave-like. At 100 MHz, air~300cm, H20 ~33cm, fat~70cm, muscle~40cm • 2)tangential BCs forcecontinuity of E x n

  6. add output port Surface current E-field in TCT Testbed Very nearly TE103 Aluminum walls & DI water not lossy, waves resonate I(t) ~ H(t). acoustic window I(t) ~ (t) E-field on central plane inside Power in E ~ 0.9 TE10 + 0.1 TE103

  7. Port design - & duck - courtesy Dan Fallon, ERI, Inc. S11 =-27.598 dB or Prefl= 0.002 Pin S21 =-0.5593 dB or Pout = 0.88 Pin S21 power from port 1 out port 2 TCT Testbed - hardware Translators - Sherry Yan, George Hanson, UWM-EE. T = Maine springtime room temp

  8. Signal Generator - Rohde&Schwarz (SML01) tunable carrier freq Pulsed Amplifier - QEI Corp pulsed amp-QEI Corp 50kW carrier freq  108MHz System

  9. Pulse profiles - time & freq • Remove carrier frequency (108 MHz)  • 2.25 MHz transducers do badly with 500ns pulse • 5 MHz transducers do well with 500ns pulse

  10. S-parameters Measure - incident & reflected power at each port: Pinc, Pref, Ptrans, Pload - for carrier freqs 70:130 MHz, w/4 microsec pulses (Eckhart) Compute (in dB scale)- S11, power reflected, ideal - dB - S21, power transmitted, ideal 0 dB

  11. S-parameters S11 S21 MHz MHz

  12. E-field measurements Slotted top & monopole antenna fabricated at UWM G. Becker, M Rhodes

  13. qualitative Can see a balloon

  14. Chimney shields effectively Conclusions Testbed performs essentially as a transmission line, preserving short temporal pulse shape. Bandwidth of testbed greater than bandwidth of QEI pulses.

  15. Thanks • WUWM for lending dir coupler line sections • Tom May (WUWM Chief Engineer) for system setup • Andrew Eckhart for collecting S-param data • Mike Schrauth for developing positioners • Mark Rhodes & Jerry Becker for slotted top & antenna

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