A 3D unidirectional antenna for microwave application

Abstract

A three dimensional unidirectional antenna for applications in lower microwave frequency is presented in this paper. Directivity and lower band operation are main design consideration of the proposed antenna. The proposed antenna provides 70 MHz of operating bandwidth operating at 1.70–1.77 GHz. The peak gain of the antenna is found to be 3.42 dBi. The dimension of the 3D structure is 40 × 20 × 10 mm3. Two 0.2 mm thick and 45 mm long walls are used as reflectors. They are used to provide enhanced directivity and gain on the two sides of the folded three dimensional radiating element. Existence of dense current on the upper radiating element along with the two reflectors are responsible for directive radiation pattern. The design of the 3D radiating element is simple enough to be fabricated using stamping metal sheet method. 3D over 2D structure is used because 3D structures can use the whole volume for impedance matching and can provide good radiation characteristics, which validates the radiation pattern of the proposed antenna. The simulation work of the proposed design is performed under Computer Simulation Technology (CST) Microwave Studio software. 0.2 mm thick copper metal is used as the antenna material for simulation purpose, as Copper material is low in cost and durable. Operating band within lower microwave frequency, compact structure, satisfactory gain, unidirectional radiation characteristics make the proposed antenna a potential candidate to be used for microwave imaging in various fields of medical diagnosis like human head imaging, microwave imaging for breast cancer detection, microwave imaging for heart failure detection etc.