Multiband Modified Yagi Antenna in a Shared Transverse Aperture

This letter presents a multiband modified Yagi antenna, which can operate at four individual frequency bands (0.87 GHz, 1.53 GHz, 2.32 GHz, and 5.55 GHz). The proposed antenna consists of four groups of Yagi elements cascading in a shared transverse aperture. Each Yagi element has one dipole as the radiator, one or two directors, and one reflector corresponding to one resonant frequency. In order to realize independent control of each frequency band, a high-impedance structure is employed between two adjacent Yagi elements, which can be used to reduce the mutual coupling as well. Therefore, the four groups of Yagi elements can work individually or in combination to achieve single-band, dual-band, tri-band and quad-band Yagi antennas. The measured results show that the proposed antenna can achieve a -10 dB impedance bandwidths of 11.5% [(0.82 to 0.92) GHz], 10.5% [(1.45 to 1.61) GHz], 17.7% [(2.11 to 2.52) GHz], and 16.2% [(5.1 to 6) GHz] for the four operating bands. The maximum realized gains for each band are 5.8 dB, 7.9 dB, 6.7 dB, and 4.8 dB.