Dual-Band Shared-Aperture Two-Dimensional Phased Array Antenna With Wide Bandwidth of 25.0% and 11.4% at Ku- and Ka-Band

A Ku-/Ka-band shared-aperture 2-D phased array antenna is proposed in this article. The antenna consists of an 8 × 8 Ku-band vertical-polarized dipole antenna array fed by a microstrip line to strip line transition and an 8 × 8 Ka-band horizontal-polarized waveguide antenna array fed by a microstrip line to substrate integrated waveguide (SIW) to fin line transition, which can be used to connect with T/R modules. For a dual-band radar system, the main challenge is to realize the shared-aperture array antenna having the wideband wide angle in the lower band and well-performed in the higher band. For example, the relative bandwidths of 25% in the Ku-band and 11.4% in the Ka-band are necessary for this work. The bandwidth of both bands is wider than that of existing works. To satisfy the wideband and wide beam coverage in two dimensions simultaneously, wideband radiating elements for both two bands are used. In this case, due to the wideband Ku-band radiator, the blind area in the Ka-band appears within the scanning process because of the parasitic mode, which should be eliminated by properly adjusting the Ku-band radiator. After that, the scanning angles of ± 60° at 14 GHz, ± 50° at 16 GHz, and ± 35° at 18 GHz, and ± 40° at 33 GHz, ± 40° at 35 GHz, and ± 35° at 37 GHz can be achieved in both E- and H-planes, respectively. Each Ku-band linear array is tightly inserted into its two adjacent Ka-band linear arrays along the wide side of the Ka-band element. Thanks to the extremely thin Ku-band endfire dipole antenna, the radiating aperture size of the Ka-band array keeps unchanged after adding the Ku-band radiators. The proposed antenna concept has been validated well by the experimental results.