A compact broadside/conical circularly polarized antenna for pattern diversity design

In this paper, we proposed a compact circularly polarized (CP) antenna with broadside and conical radiation patterns for pattern diversity. The broadside CP pattern is generated by a corner-truncated patch antenna. The conical CP pattern is generated by a rotationally symmetric folded metallic strip, which is fed at centre. A prototype of the diversity antenna operated at 2.4 GHz has been built. Simulations show that the overlapping frequency bandwidth with reflection coefficient less than -10 dB and axial ratio (AR) less than 3 dB for both broadside and conical patterns is about 1 % (2.411 ~ 2.433 GHz). High isolation (below -30 dB) is also achieved in the overlapping band.