Design of Semi Circular Floral Shape Directive UWB Antenna for Radar based Microwave Imaging

Radar based microwave imaging are very popular now a days for applications in medical field such as the detection of breast cancer at early stage. A highly directive Ultra Wide Band antenna is the key component for these applications as it is used to radiate and receive UWB pulses. An antenna with semi-circular-floral shape (SCFS) patch is designed in which ground plane is modified by inserting stepped slots and is developed for radar-based microwave imaging applications in the present paper. This antenna is designed through insertion an elliptical slot having fractional/partial rectangular ground structure. Three symmetrical rectangle stepped slots are inserted in ground plane under 50-ohm micro-strip feed line having integration with stepped-quarter-wave transformer. It is used to achieve an ultrawide impedance bandwidth, high directivity and least half-power-beam-width (HPBW) of antenna. Proposed antenna achieve an ultra-wideband of 4-18GHz which covers a fractional bandwidth of 127% (S
₁₁
<;- 10dB). The maximum radiated direction is moves from 45° -130° and HPBW decreases from 52° 30° in attained frequency band. Furthermore, directivity varies among 3-10dBi in 4-18GHz. The optimized dimensions of proposed antenna are 30 x 30 mm
²
, which is designed and fabricated on FR-4 substrate taking thickness of 1.6mm and dielectric constant of 4.3. Proposed antenna structure is designed via Electro-magnetic CST, ADS simulator. Finally, the simulated or computer-generated results are validated through measured results.