Abstract
A novel electromagnetically short antenna with parasitic microstrip cap shape is shown in this paper. The antenna is composed of a U-shaped parasitic microstrip line (cap) excited by coupling with the feed line at patch. The antenna is fabricated in FR4 substrate with dielectric constant, epsilon r=4.55 and thickness of 1.6 mm. Optimization of the proposed antenna is done using modified Particle Swarm Optimization (PSO) algorithm in ZELAND IE3D software environment. That gives resonance at selected frequencies and increased gain than the initial design. By using circular slot at the ground plane with miniaturized structure, dual-band covering 5.29 GHz to 5.89 GHz (C-band) and 7.93 GHz to 8.86 GHz (X-band) is achieved. A fractional bandwidth of 10.74% at C-band and 11.08% at X-band is achieved. A measured gain of 5.65 dBi and 6.61 dBi is achieved at C-band and X-band respectively, with a circular polarization. Gain improvement is achieved compared to the initial design by more than 2 dBi (average) in the selected frequency for the given resonance using modified PSO optimization.