Dual-Band Shared Aperture Reflectarray and Patch Antenna Array for S- and Ka-Bands

In this communication, a dual-band shared aperture antenna is presented. The proposed antenna achieves dual-band operation by
housing both a low-frequency patch antenna array and a high-frequency reflectarray in the same aperture area. The two different antenna types are combined into a single antenna product without any significant performance loss. The antenna has a layered structure that allows the low frequency antenna array to have both a sufficient impedance bandwidth and realized gain. The antenna has a shared aperture since the high frequency reflectarray has unit elements within the area of the low frequency patch antenna array. This allows the antenna to achieve a good realized gain in the high-frequency band. The proposed antenna is fabricated and measured. The prototype is designed for S- and Ka band resulting in a frequency-ratio of 7.37. The shared aperture size is 156 mm × 156 mm × 4.624 mm. Measurements show the impedance bandwidth to be 200 MHz (6%) and 5.1 GHz (20%) and the peak realized gain to be 13.70 dBi and 27.65 dBi at 3.5 GHz and 25.8 GHz, respectively A very good agreement between the simulated and measured results is observed.