A dual-band, dual-polarized antenna and a switchable multi-beam antenna array are introduced in this paper. Composed of two orthogonal annular dipoles, the proposed ±45◦ polarization diversity antenna has two simulated impedance bands: 2.39 GHz ∼ 2.85 GHz and 3.39 GHz ∼ 3.97 GHz, with VSRS < 1.5 and isolation > 28.5 dB. The simulated gain of the antenna is 8.5 dBi at the lower frequency band, and 9.1 dBi at the higher frequency band. In order to compose a 5 ∗ 3 polarization diversity antenna array, two 3-to-15 feed networks are employed and placed together, one for each polarization. The whole feed network is manufactured using microwave substrate AD255C with thickness of 0.762 mm and dielectric constant of εr = 2.55 and its size is limited to 340 mm ∗ 200 mm ∗ 30 mm. The output phase as well as the amplitude of each output port of each network is identical. To realize switchable multi-beam capability in horizontal plane, two microwave switches are used for the array. Connected to 3 out of 6 input ports, one switch has 4 gears and the input phase of the feed network is selected from 4 groups of fixed values. Thus the input phase of the antenna elements can be controlled. In other words, this antenna array can radiate at 4 different angles (within ±30◦ at 2.6 GHz), yet not simultaneously. Simulated results of the antenna and antenna arrays are presented and discussed. Both the return loss, port isolation and the gain are good enough for civil communication applications.