A compact multiband planar antenna using modified L-shape resonator slots.

A multiband planar antenna designed and proposed with resonator slots is presented. The proposed antenna consists of a planar hexagonal patch composed of two pairs of resonator slots. The antenna is designed using Isola FR408 substrate (ε = 3.68 and tanδ = 0.0092) with a compact dimension of 21 × 28 × 1.6 mm. The designed antenna has good impedance matching and radiation characteristics for the desired multiband frequencies. Multibands are obtained by etching two pairs of modified mirror-imaged L-shaped resonator slots on the hexagonal planar patch. Simulated and measured results of the antennas' reflection coefficient are provided and there is good agreement between the simulation and measurement results. The antennas' measured peak gains are between 2 dB and 5 dB and measured efficiencies are between 40% and 80%. The proposed antenna, when compared to other antennas, exhibits multiband characteristic by using a single-feed structure and generates different combinations of isolated lower frequency bands in miniature size. The antenna has stable directional radiation patterns and has the potential to meet the requirements of wireless communications applications.