Small dual‐band inverted F antenna using series resonator

Design procedure of a small dual‐band Inverted F Antenna (IFA) using a series resonator is proposed. A series resonator was loaded to the right end of the IFA to make different loading effects according to the resonant frequency of the antenna. When the resonant frequency of the series resonator is between the first and second resonance frequency of the designed antenna, the first resonance has capacitor loading effect while the second resonance has inductor loading effect. These loading effects lead small antenna size at the dual‐band. Both frequency tuning and impedance matching techniques are also proposed. The proposed antenna was simulated and fabricated to be able to resonate at 2.4 GHz and 5.8 GHz and the antenna proved to have had the bandwidth 200 MHz at 2.4 GHz and 400 MHz at 5.8 GHz with the size of 0.12 λ × 0.05 λ. As a result of measuring radiation pattern, maximum efficiency was 88% at 2.4 GHz and 90% at 5.8 GHz.