الفهرس | Only 14 pages are availabe for public view |
Abstract In this thesis two microstrip patch, linear antennas arrays are designed and analyzed using CST and HFSS simulators. The goal of this thesis is to detect cancer tumors, especially in the brain and kidneys. Brain tumor detection was by simulating the reflection coefficient of the antenna which was put on the top of a head model with and without tumor. The difference in S11 was enough to detect small tumors even their radii were 2.5mm. The first patch antenna array used an EBG in the ground plane. Two types of EBG are proposed. The first type is a rectangular lattice of holes which produced an increase in S11 by 19% at the same resonance frequency which is 3.9 GHz with and without tumor. The second one is a squared lattice of holes that presented an increase of 27 % in S11. It also provides a 2.9% shift in the resonant frequency at -10 dB on a head phantom with a brain tumor compared to without a tumor. The electric field, magnetic field, and current density are calculated in each type of EBG. A remarkable difference has been observed between with and without tumors especially on the squared lattice. One-, two and four- elements linear antenna arrays are designed to be put at a 10-mm distance from the head phantom. The purpose of antenna arrays is to provide sufficient energy to penetrate human tissues. The directivity was 6.65 dB, 8.5 dB, and 12 dB in one element, two elements, and four elements respectively. The S11 is calculated for each antenna on a head phantom with and without a tumor. The S11 values are increased by 1.05dB, 2.73dB, and 4dB for the three cases respectively. Also, the E and H fields, current density, and specific absorption rate SAR are calculated. In addition, the second antenna array was also used for brain tumor detection. The antenna used was a reconfigurable four-element linear array of squared microstrip patches. Two arrays were designed one circularly polarized, the other linearly polarized. The antenna operates at Industrial Scientific and Medical (ISM) frequency 2.4 GHz. It was designed on FR-4 (lossy) substrate of relative permittivity 4.3 and thickness of 1.6 mm. To feed the array, a corporate feeding network was designed. The reconfigurability of the array was achieved using three single pole double throw (SPDT) switches. Two models of the human head were used; a specific anthropomorphic mannequin (SAM) model, and a 3-D head model consisting of four different head layers: skin, fat,III skull and brain. The simulation calculates the reflection coefficient (S11) with and without tumor for circularly polarized (CP) and linearly polarized (LP) linear array. Calculations were taken for four sizes of the array. The best results were obtained with the four-element circularly polarized array. An increase in S11 of 1188% was obtained. Tumors as small as 5 millimeters (four-layer model) and 2.5 mm (SAM model) can be detected. Specific absorption rate (SAR) was calculated and found to be within the safe limit. A circularly polarized four-element linear antenna array was fabricated. The measured S11 and radiation pattern are in excellent agreement with simulated ones. Moreover, kidney cancer detection was also one of our goals in this thesis. The previous CP and LP linear antenna arrays were also used to detect kidney tumor stages. Renal cancer tumors are divided into four phases where the increase in reflection coefficient and the shift in resonance frequency are calculated for each stage. At 2.4 GHz, the S11 for the four stages of cancer are 5, 6.9, 14.1, and 16.6 dB, respectively. For the four stages, there is also a shift in resonance frequency of 2, 3, 18, and 28 MHz, respectively. In its advanced stages 3 and 4, the tumor is simple to detect. LP antenna was simulated and calculated ∆S11, and the shift in frequency at 2.3 GHz. The increase in S11 of CP than LP was 455.6%, 155.6 %, 261.5 %, and 186.2 % form stage 1 to stage 4 respectively. The shift in resonance frequency for the early stages is too small. Therefore, detection depends mainly on the increase in S11. The shift in resonance frequency and increase in S11 are large for advanced stages of the tumor, which makes detection easier. Computed specific absorption rate (SAR) is found to be less than the safety levels. |