Design And Research Of 2.45 GHz Focused Array Antenna For Microwave Hyperthermia

Focusing antenna is a kind of antenna which is used to reduce the energy spread when the electromagnetic wave transmission takes place in space.It can gather the electromagnetic wave or focus the energy on a certain target.For an ideal rectangular planar caliber focusing antenna,the optimal continuous aperture distribution is the amplitude satisfying the ellipsoid function distribution and the phase distribution satisfies the spherical wave distribution.In practice,the continuous aperture distribution of the ideal focusing antenna is impossible to achieve.One approach is to use the irregular conformal antennas or discrete planar antenna array to approximate the continuous distribution.But an optional method has not been found.In addition to the discrete planar array of focusing antennas,there are many other types of focusing antennas,including the one placing a lens in front of a microstrip array,and the one arranging the antennas in a spherical array.These two main design methods,not only will increase the size of the array,but also increase the difficulty of implementation.The use of microstrip technology to design a planar focusing antenna can not only avoid these two problems,but also can simplify the structures,and have light weight,relatively low cost features.The main research and results of this thesis are summarized as follows:1.Based on the analysis of planar array focusing theory,the design and fabrication of the near field focusing antenna array are completed.The array element is an embedded rectangular microstrip patch antenna.The array arrangement is made in the form of planar configuration.The number of array element is 16 arranged in4 ? 4 formation.Parallel feed is used.The design of the T-type power divider and the quarter wavelength impedance converter have also been completed.In order to measure the near-field focusing effect of the antenna array,a near field measurement system is established.Both simulation and measurement results agree well.The electric field energy at 300 mm away from the array aperture is the largest.The crose-section of focal spot produced by the focusing antenna array in space is circular and the spot has an approximate diameter of 110 mm and a focusing depth of 62 cm.2.This thesis also introduces the basic principle of microwave hyperthermia and the basic types of microwave heat treatment antenna.The designed focusing antennaarray is then applied to the medical field for microwave heat treatment.A human body tissue model is set up,and then the focusing array antenna is applied to the tissue model.The tissue model is placed at 260 mm away from the array aperture and simulated in the electromagnetic simulation software.The simulation results show that most of the electromagnetic wave energy is absorbed by the tissue,and the specific absorption rate is the largest at 285 mm away from the aperture,which shows that the temperature rise is the fastest at the same time.This antenna array can thus be used as a microwave hyperthermia antenna array.