A Microstrip Yagi Antenna With an Enlarged Beam Tilt Angle via a Slot-Loaded Patch Reflector and Pin-Loaded Patch Directors

In this letter, a microstrip Yagi antenna with a resonating patch driver, one slot-loaded patch reflector, and two pin-loaded patch directors is proposed. Different from all the reported counterpart antennas, the lengths and widths of all the patch elements involved herein are set to be the same, and a parasitic patch reflector and patch directors are realized by loading the slot and shorting pins on the patches, respectively. For a square patch, its resonance frequency can be reduced by etching out a slot, acquiring a reflective function. However, its resonance frequency can be increased by adding a pair of shorting pins underneath the patch, thus acquiring a directive function. By placing these two types of parasitic patches in the two sides of the driving patch radiator, an alternative microstrip Yagi antenna can be constructed to achieve a quasi-endfire radiation pattern with an enlarged beam tilt angle. A prototype operating at 5 GHz is finally fabricated and tested. The measured results achieve an impedance bandwidth of 8%. In addition, the maximum deviation angle reaches approximately 56° from the broad side, and its 3 dB beamwidth in the xoy plane exceeds 62°.