Quad Band Compact Size Trapezoidal Pifa Antenna

New shapes of slot loaded trapezoidal PIFA antenna are investigated in this paper. Double and triple slots are inserted to reach tri and Quad band operations, respectively. The antennas resonance frequencies are selected in the s-band and c-band to be compatible with commercial wireless communication applications. The antennas are designed, analyzed and fabricated using cheap substrates as foam with εr = 1.07 and FR4 with εr = 4.5.Compact size operation is achieved by using trapezoidal shorted capacitive plate between the antenna radiator and the Ground plane. This reduces the antenna size by 67.5% from conventional λo/4 PIFA. The antenna characteristics are acceptable in all cases with gain about 6 dBi in average. The 10 dB impedance bandwidth is about 5% in average for all operating frequency bands. The radiation pattern is acceptable in both E-plane and H-plane, respectively with back to front ratio of less than −15 dB and 3 dB beamwidth ≥100°. The substrate thickness h = 3 mm (≤.012λo 1, where λo 1 is the lowest resonating mode wave length for final designed antenna). The four different designs are fabricated with photolithographic technique and measured with HP8719ES vector network analyzer. The results show good agreement between the simulation and measurements except some minor accepted deviations due to fabrication tolerated errors.