DESIGN AND ANALYSIS OF UWB ANTENNAS FOR MICROWAVE IMAGING BASED MEDICAL APPLICATIONS

Abstract

Microwave imaging is renowned as one of the most promising technologies in the medical application of abnormality or lesion diagnosis. The underlying concept ofactive microwave imaging is to diagnose a lesion by evaluating the large dielectric difference between normal tissue and abnormal tissue employing antennas as the key element. A salient feature of microwave imaging antenna is attributed to its ultra-wide impedance bandwidth as found in the previous research works. In this research work, an ultra-wideband (UWB) bow-tie antenna and a monopole antenna are designed and analyzed for simultaneous detection and localization of brain tumor and brain stroke respectively using a microwave imaging technique. The bandwidth enhancement of the proposed bow-tie antenna is accomplished by dint of a self-complementary structure while the bandwidth of the proposed monopole antenna is enhanced with defected ground structure (DGS) and trident-shaped feeding strip. Furthermore, a six-layered human head phantom composed of skin, fat, bone, dura, cerebrospinal fluid (CSF), and brain is modeled in which a malignant tumor, hemorrhagic stroke, and ischemic stroke are inserted individually upholding the safety regulation of specific absorption rate (SAR). In addition, the monostatic radar-based delay-and-sum (DAS) beam-forming or confocal microwave imaging algorithm is developed for visualizing the location of the lesion explicitly via image reconstruction. It is exposed from the simulation results that the proposed bow-tie antenna achieves superior performance to the conventional counterparts, specifically, in respect of bandwidth and radiation efficiency whereas the proposed monopole antenna attains superiority regarding bandwidth and size in particular. Brain tumor detection is assured with a drastic improvement of current density and SAR of the proposed bow-tie antenna compared to the normal healthy tissue. However, the hemorrhagic stroke is detected with an excess of current density and SAR of the proposed monopole antenna in comparison to the healthy brain while the situation reverses in the case of the ischemic stroke. Eventually, the relevant microwave images are reconstructed reliably in two-dimension with a high spatial resolution. Hence, the proposed research work might save human lives by the alleviation of mortality rate due to brain abnormalities through an early and quick diagnosis.