On the Possible Use of Microwave-Active Imaging for Remote Thermal Sensing

Abstract

Fig. 2. Isolation versus frequency for passband VSWR = 1.05, fCO= 3.3 GHz, the resistances of the diodes when forward biased (or at high power) for case I and case II, are 2.47 and 1.0 Q respectively. each and one series inductance of 1.9 nH, realized by a short coaxial high-impedance line length. At forward bias or at high power level, the capacitances Cl and C3 will be replaced by the resistances of the diodes. Let us assume that the resistance of each diode is 2.470. The isolation of the switch/limiter is crdculated using~BCD matrices [4] and is given by al = 10log [451 .26+ 2902~2 ] dB (1) where~is the frequency in GHz. al is plotted against frequency as shown in Fig. z Case II: Inductance as the First Element (Fig. 2) For the same specifications as in case I, the low-pass filter elements values are gl = 0.6181, gz =1.2026, g~=1.4130, g4 = 1.2026, and g~= 0.6181. Therefore, L1=L5=~=l.49nH gz-=1.16pF C2 = C4 = znfco~o L = g3zo 3-=3.4nH. 2 ?rfco Therefore, the required switch/limiter with passband VSWR of 1.05 will consist of two diodes with capacitances of 1.16 pF each and three series inductances (1.49 nH at the input, 3.4 nH in between the diodes, and 1.49 nH at the output) realized by short coaxial high-impedance line lengths. At forward bias or high power level, the capacitances C2 and Cl are replaced by diode resistances. In order to compare the merits of the circuits in cases I and II, we have to take p-in diodes of the same cutoff frequency jC. Assuming the same value for reverse-and forward-biased series resistances, we have~C= l/2 TClRl =1/29rC2R2. Therefore, R2 = (C1/C2)Rl =1.0~. Where RI (= 2.47 Q) and R z are the forward-biased series resistances of each diode in case I and case II, respectively. The isolation a2 is calculated using A BCD matrices and is given by [1]

Optimal Constrained Field Focusing for Hyperthermia Cancer Therapy: A Feasibility Assessment on Realistic Phantoms

“…In this respect, it is also worth mentioning the possibility of monitoring via inverse scattering the permittivity variation with temperature which was devised in some pioneering papers by Bolomey and co-workers [34,35].…”

Initial Clinical Experience with Microwave Breast Imaging in Women with Normal Mammography

“…With respect to radar technology, the most advanced concepts appear to be ultra-wideband microwave imaging via space-time beamforming [Xu et al 2005;Davis et al 2005], confocal microwave imaging [Fear et al 2002;Yun et al 2005] and near field synthetic focusing [Benjamin et al 2001]. Studies of microwave tomography also exist and include reports by Bolomey et al [1982Bolomey et al [ , 1983Bolomey et al [ , 1985, Liewei et al [2002], Souvorov et al [2000], Bulyshev et al [2001], Meaney et al [2000Meaney et al [ , 2003, Ciocan et al [2004], among others. Most of these efforts (either radar or tomography) are occurring at the prototyping stage where the goal has been to identify and optimize the important design considerations rather than report on the electrical characteristics of breast tissue per se.…”

Dielectric properties of human urine at microwave frequencies

“…Microwave medical tomography is emerging as a novel nonhazardous method of imaging for the detection of fracture, swelling, and diagnosis of tumors. For active and passive microwave imaging for disease detection and treatment, monitoring requires proper knowledge of the dielectric properties of body tissue at the lower microwave frequencies [12][13][14]. Studies on the variation of dielectric properties of body fluids and calcifications at microwave frequencies have revealed that diagnosis is possible through this method [15][16].…”