Collinear antennas based on coplanar waveguide

With the increasing use of coplanar waveguide (CPW) and related planar structures as transmission lines for MICs and MMICs, particularly at millimetric frequencies, there is a need for a complete family of compatible planar printed antennas. A uniplanar printed construction offers many opportunities for inexpensive production and flexible design, especially in roles complementary to those of the microstrip patch. This paper concentrates on the problem of producing omnidirectional radiators. For omnidirectionality, the planar geometry implies that the radiator must be at a board edge and be significantly separated from rest of the MIC layout. It must have polarisation parallel to the symmetry axis of the pattern (E-dipole type). The polarisation and symmetry axis, however can either be (a) parallel to the board edge; or (b) normal to the board edge, which is the case examined