Design and Fabrication of Microstrip Patch Antennas for Brain and Breast Cancer Detection

Abstract

In this thesis, primary antenna used is microstrip patch antenna. Two antenna designs are fabricated in this work. First one describes a hexagonal shaped wearable antenna with circular slots and reduced ground plane for the detection of brain cancer which operates at ISM (Industrial, Scientific, and Medical) band at 2.4-2.4835 GHz. The antenna is fabricated on a FR-4 substrate having thickness 0.8 mm and relative permittivity 4.35 F/m. The actual size of the antenna is 30 mm × 20 mm. The designed antenna has an advantage that its dimensions are small which makes it practically wearable on human head. This antenna is placed on the human head phantom model which consists of skin layer only and is simulated using CST Microwave Studio. S-parameter analysis is used to identify whether or not tumor is present in the brain. The S-parameter results of a Human Head Phantom Model with cancerous tissue that contains a 5 mm tumor inside the Human Brain (-38.788 dB) are different from the S11 results of normal head (-31.955 dB) at the resonance frequency of 2.46 GHz. Various other performance parameters are also analyzed for the proposed antenna such as Voltage Standing Wave Ratio (VSWR), SAR and radiation pattern. SAR value of the antenna with the input power of 2mW is found to be 0.3747 W/Kg at the resonance frequency of 2.46 GHz as given by ICNIRP and FCC guidelines that SAR should not exceed 1.6W/kg. Finally, a comparison between simulated and measured results without cancerous tumor is illustrated which verifies the prototype of proposed antenna. Second paper describes the detection of tumor in human breast tissue using a microstrip patch antenna operating at MICS(Medical Implant Communication Services) band which is in between 402-405 Mhz. This antenna is designed and fabricated on the FR-4 substrate with thickness 1.6mm. The actual size of the antenna is 15mmX15mm. To analyze the characterstics of the antenna, it is embedded in the gel type tissue material whose electrical properties is the same as that of the human skin in case of conductivity and permittivity. MICS band is preferable because of its docility towards higher bandwidth. There is a difference in the simulated and measured return loss of the antenna which indicated the presence of tumor inside the breast. Various parameters are also measured for the designed antenna such as return loss, VSWR (Voltage Standing Wave ratio), Radiation pattern, Directivity and Gain at the resonance frequency of 402-405 Mhz. A comparison technique is used to identify whether or not tumor (benign or malignant) is present in the breast.