Considering the conditionality of the Polarization Sensitive Array (PSA) in realization, an original Alternate Polarization Array (APA) is proposed. The ultimate filtering performance is presented theoretically and numerically, which is contrasted with that of PSA comprehensively. Compared with the PSA, the filtering performance of APS approaches that of PSA, but the equipments and the degree of freedom is cut by half. The APA overcomes the disadvantages in implementation of PSA. Therefore, APA has great potential to be used in arrayed radar and other fields. 