Design And Application Of Ultra-wideband Patch Antenna

UWB patch antenna is an important participant in breast cancer detection system,and its performance will affect the work of the whole equipment.Therefore,the design and improvement of UWB patch antenna with practical value has become a hot topic for scholars nowadays.In the first part of this paper,an UWB patch antenna with the size of20.6mm×23mm×1.54 mm and operating frequency band of 3.6 ～ 12 GHz is designed.The antenna is designed on FR4 plate,and rectangular and semicircular grooves are added on the ground surface to improve the antenna bandwidth.The maximum gain of the antenna reaches6.47 d Bi at 8.4GHz,which has the advantages of wide band,small size and high gain.By establishing a simple breast model and using electromagnetic simulation to simulate the r E value of the breast model at 8.4GHz,the results show that the maximum difference of r E value between the tumor and the tumor is 1.6V,so it can be seen that the antenna is suitable for breast cancer detection.However,due to the non-bendable properties of the rigid substrate,there are some limitations in many fields.Therefore,in the latter part of this paper,a patch antenna is redesigned with flexible substrate.Polyimide is selected as the medium,and a new type of radiant copper is engraved on both sides.In practice,certain frequency bands need to be shielded.In order to shield WLAN band,a symmetrical C-shaped slot is designed on the radiation patch.By optimizing the opening size of the C-shaped slot,the notch function of 5.1to 5.9GHz is realized,covering WLAN band.The antenna is designed on a flexible polyimide substrate.The simulation software is used to test the variation curve of the antenna’s echo loss parameters under different bending degrees.It is found that the antenna has a small performance loss and good robustness.For the flexible antenna designed in the project,the SAR value of the tissue model will also change when the distance of the antenna above the different breast simulation model changes.This project studies the SAR value of two different standards(FCC and ICNIRP).When the SAR value reaches the safety limit,the distance of the flexible antenna model is 6mm.The height of the antenna distance model will be an important reference value for establishing the coordinate system.Finally,in order to verify the effectiveness of the designed flexible antenna in breast detection,a simulation test was carried out on the antenna and biological tissue under the established coordinate system.When the tumor radius was 2mm,3mm,and 4mm,the maximum average SAR value was 13.025W/kg,12.426W/kg,and 6.4613W/kg,respectively.This consequence revealed that with the enhancement of tumor radius,the maximum average SAR value of the tumor gradually decreased.This result has an effective reference value in the diagnosis and treatment of breast cancer,especially in the safety of normal tissues and cancerous tissues.In addition,in the process of the radius change of the spherical tumor model,the SAR value of the tumor part is far greater than that of other biological tissues,which indirectly proves the feasibility of the designed antenna for tumor detection and helps to carry out microwave imaging in the later stage.