Filtering Antenna With Two-Octave Harmonic Suppression

A novel second-order antenna with filtering performance and two-octave harmonic suppression is proposed. In order to reduce the effects of the harmonics of the antenna, two types of antennas [planar inverted-F antenna (PIFA) and patch] with different resonant characteristics are integrated into the design. Compared to the traditional patch antennas, this integrated work can not only eliminate the high-order harmonics of the antenna but also improve the in-band bandwidth and frequency selectivity. The second- and fourth-order harmonics of the patch are suppressed because of the detuned harmonic performance of the PIFA and patch. The third-order harmonic is eliminated by integrating notch resonators in the PIFA. A prototype that works at 2.4 GHz is developed to demonstrate the PIFA-patch integration scheme. Measured and simulated results of antennas agree well with each other, demonstrating good performance of bandwidth, second-order filtering, radiation, and wideband harmonic suppression (up to 11 GHz).