This paper proposes a coplanar waveguide (CPW)-fed semiloop antenna with switchable linear polarization and radiation pattern. This design uses a novel asymmetric coplanar strip line (ACPS) circular ring to produce even or odd modes of the CPW, which can generate vertical or horizontal polarization in the semiloop antenna. The modes of the ACPS circular ring can be switched by controlling the on/off state of the PIN diode, and only a two-bit control signal is required to select the operating mode. The proposed polarization switchable antenna uses only one metal layer of the printed circuit board. The center frequency of the dual-polarization antenna was determined to be 2.45 GHz, and the −10 dB impedance bandwidths were determined to be 12.86% and 4.92% for vertical and horizontal polarization, respectively. The antenna parameters, such as the return loss, gain, and radiation patterns, are also presented for validating the proposed design.