Design of a compact dual-polarised slot antenna with enhanced gain

A compact dual-polarised slot antenna with improved gain is presented in this study. A cross-shaped slot antenna fed by two orthogonal microstrip feed lines is proposed to achieve dual polarisations. A symmetrical feeding structure is employed to realise high isolation between the two ports by utilising a one-to-two divider. The working principles of the slot antenna fed by a fork-like microstrip are investigated in detail for the first time. In addition, a parasitic cross-shaped slot is added to improve the impedance matching and directivity of the proposed antenna. The measured results show that the proposed antenna can cover the whole WiMAX band ranging from 3.27 to 3.68GHz. The cross-polarisation levels are less than -30dB in the boresight direction and lower than -25dB within 3-dB beamwidth in both E- and H-planes. The gain of the antenna is 9.15dBi +/- 0.25dB and the port isolation is greater than 27dB across the operating band.