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Published byKathryn Bond Modified over 9 years ago
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TCT testbed RF Testbed for TCT D Fallon - Electronics Research Inc L Yan, G Hanson, S Patch - UWM
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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?
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TCT testbed TCT Wave Eq Model + homog ICs for I(t)= (t) thermal mechanical electrical
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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
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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
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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 10 + 0.1 TE 103 I(t) ~ (t)
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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 =-0.5593 dB or P out = 0.88 P in S 11 =-27.598 dB or P refl = 0.002 P in T = Maine springtime room temp
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TCT testbed System Signal Generator - Rohde&Schwarz (SML01) Pulsed Amplifier - QEI Corp 50kW pulsed amp-QEI Corp tunable carrier freq carrier freq 108MHz
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TCT testbed 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
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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
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TCT testbed S-parameters S 11 S 21 MHz
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TCT testbed E-field measurements Slotted top & monopole antenna fabricated at UWM G. Becker, M Rhodes
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TCT testbed Can see a balloon qualitative
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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
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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
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