Circular Patch Antenna Array with Defected Ground Structure for Ka-band Radar Applications

The paper proposes a four-circular elements microstrip patch array antenna with Defected Ground Structure (DGS). The antenna array designed and simulated by three steps, started by a single element design using inset feeding technique, the array antenna was combined using a T-junction power divider, and a Microstrip Curved Bend power divider was constructed. Simulations predict a good matching impedance at 30 GHz with a return loss of -40 dB. Two dumbbells shaped defected ground structure have been integrated below the transmission line, which will allow to adjust transmission line inductance and capacitance in order to increase bandwidth up to 3.1 GHz, without significant effects on radiation pattern. A prototype of the antenna was designed on an FR-4 substrate with a dielectric constant (ε _r ) of 4.3 and loss tangent (tanδ) of 0.025 with thickness of 0.465 mm. The array antenna is designed and simulation using two electromagnetic solvers.