A Differentially Fed Hybrid Dipole, Slot, and Patch Antenna With Unidirectional Radiation Patterns

A differentially fed hybrid dipole, slot, and patch antenna with unidirectional radiation patterns is designed in this article. The antenna consists of a metal strip, a patch loaded with a slot, and a simple wideband 180 degrees out-of-phase power splitter (OPS). The OPS can generate two signals with the same amplitude but accurate phase difference of 180 degrees to achieve one-port differential feeding. The hybrid modes of different types of antennas, i.e., dipole, patch, and slot, are excited to obtain five bands. Additionally, the TM01, TM21, and TM03 modes of the patch antenna are excited. By loading the slot and the metal strip, the radiation pattern of TM21 mode is converted from conical to broadside, and the ground walls further concentrate the radiation pattern. The ground walls also enhance the antenna gain, with the increments of 1 dB at 3.5 GHz, 3.4 dB at 4.65 GHz, 4.1 dB at 5.5 GHz, and 1.4 dB at 6.3 GHz. Finally, the antenna is fabricated and measured. The measured results show that the antenna covers five impedance bandwidths (IMBWs) of 1.85-1.91 GHz (3.2%), 3.13-3.66 GHz (15.6%), 4.62-4.98 GHz (7.5%), 5.10-5.82 GHz (13.2%), and 6.10-6.57 GHz (7.4%) for s11 < -10 dB. The radiation patterns at each band are toward the broadside, with peak gains of 5.1 dBi at 1.85 GHz, 8.8 dBi at 3.45 GHz, 8.8 dBi at 4.7 GHz, 12.2 dBi at 5.5 GHz, and 9.7 dBi at 6.3 GHz.