In order to satisfy the requirement of broadband microwave medical diagnosis ( in the condition of low microwave band) ,a novel compact composite single direction planar antenna is proposed. The main part of the antenna is combined with a ring and a dipole staggered structure in order to obtain a wide bandwidth. First,in order to reduce the first resonance of the antenna and enhance the directivity of the antenna,two slots are added to the vertical arm of the loop antenna. Then,a pair of rectangular slots and a trapezoidal groove are respectively opened on the transverse arms of the annular antenna and the dipole antenna,so as to reduce the influence of the added slot on the input impedance. The antenna is mainly to a direction of radiation,and compared to other similar design,its size is small 50%,0.23 m×0.23 m. Under the condition of 0.65 GHz~1.15 GHz,the measured relative bandwidth is 55%,and the peak gain and the front and back ratio are 3.7 dB and 10.6 dB. In order to verify the practicability of the antenna,it is used in the configuration of the array,and the pulmonary edema test is carried out in the experi-mental environment. The experimental results show the effectiveness of the antenna design.%为了满足宽带微波医疗诊断(在低微波波段条件下运行)的要求,提出了一种新的小型复合单方向平面天线.该天线的主要部分结合了环形以及偶极交错式结构,以便获得较宽的带宽.首先,为了降低天线的第一共振并增强天线的指向性,在环形天线的立臂上添加两个开槽.然后,分别在环形天线和偶极天线的横臂上开辟一对长方形槽和梯形槽,以便减少添加的开槽对输入阻抗的影响.该天线主要是向一个方向进行辐射,且相较于其他相似设计,其尺寸要小50%,为0.23 m×0.23 m.在0.65 GHz~1.15 GHz的条件下,实测相对带宽为55%,并且峰值增益和前后比分别为3.7 dBi和10.6 dB.为了验证天线的实用性,将其用于阵列配置中,并在实验环境中对其进行了肺水肿测试,实验结果显示了该天线设计的有效性.
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