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

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

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

TCT testbed 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

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

TCT testbed E-field in TCT Testbed Power in Very nearly TE 103 Aluminum walls & DI water not lossy, waves resonate I(t) ~ H(t). acoustic window E-field on central plane inside Surface current add output port E ~ 0.9 TE TE 103 I(t) ~  (t)

TCT testbed TCT Testbed - hardware Translators - Sherry Yan, George Hanson, UWM-EE. Port design - & duck - courtesy Dan Fallon, ERI, Inc. S 21 power from port 1 out port 2 S 21 = dB or P out = 0.88 P in S 11 = dB or P refl = P in T = Maine springtime room temp

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

TCT testbed Pulse profiles - time & freq Remove carrier frequency (108 MHz)  MHz transducers do badly with 500ns pulse - 5 MHz transducers do well with 500ns pulse

TCT testbed S-parameters Measure - incident & reflected power at each port: P inc, P ref, P trans, P load - for carrier freqs 70:130 MHz, w/4 microsec pulses (Eckhart) Compute (in dB scale) - S 11, power reflected, ideal -  dB - S 21, power transmitted, ideal 0 dB

TCT testbed S-parameters S 11 S 21 MHz

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

TCT testbed Can see a balloon qualitative

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

TCT testbed 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