A K-/Ka-band planar shared-aperture beam-scanning array with a high-isolation for the emerging mm-Wave shared-aperture terminals

A planar K-/Ka-band shared-aperture array with the steerable beam is proposed in this paper. The substrate-integrated coaxial line (SICL)-excited short-circuited-stub-loaded longitudinal slot and substrate-integrated double line (SIDL)-excited slot-loaded patches are employed to radiate K-/Ka-band waves, respectively. Then, to constitute the 1-D K-/Ka-band arrays, the center-fed SICL feed network and SIDL-based full differential feed network are introduced to widen the bandwidth. Finally, the GCPW-to-SICL and GCPW-to-SIW transitions are adopted to excite the proposed array, respectively. Both SICL and SIDL feed networks are located below the radiating aperture. Those arrays are interleaved and shared the same radiation aperture, as well as the shielding metallic-via-array for achieving a compact footprint. To excite the above radiating elements, the SICL center feed network and fully differential feed network are introduced to widen the bandwidth. The channel isolation is improved by utilizing the fully differential feed network and the filtering response of the SIW. Equivalent circuits are proposed for designing the proposed antenna. Thanks to the miniaturized geometries of K-/Ka-band arrays, the proposed antenna is able to scan up to 60 degrees and 35 degrees at K-/Ka-band, respectively. As an example, a shared-aperture array with a steerable beam is developed and fabricated by using a multilayer printed circuited board with the designed frequencies of 19 GHz (17.7-20.2 GHz) and 29 GHz (27.5-30 GHz). The aperture dimension of the array antenna is 49.6 mmx40.75 mm. A good consistency between the simulation and measurement is acquired. The measured peak gains in K-/Ka-band are 16.6 and 17.6 dBi. When the radiation beam points to 0 degrees, the 3-dB gain bandwidth at K-band is 14.9% (17.4-20.2 GHz), while the 3 dB gain bandwidth at Ka-band covers from 27.6 to 30.4 GHz, i.e., a bandwidth of 9.7%. When the radiation beams are deflected to 60 degrees and 35 degrees, the measured gains of the proposed antenna fluctuate by 3 and 1.3 dB at the designed frequency, respectively. The radiation efficiencies at the scan angle of 0 degrees at K-/Ka-band are 64% and 41.1%, respectively. The measured channel isolations in the K-/Ka-band are greater than 35 and 37 dB in the scanning range, respectively. The measured results verify that the merits of the proposed array in bandwidth, isolations, beam-scanning coverage, and profile height can be applied to the emerging millimeter-wave shared-aperture terminals.