Optimized design of unique miniaturized planar baluns for wireless applications

The high frequency balun network has proven to be an important component in the design of certain RF and microwave system topologies-especially in wireless communications system architectures. This work describes the optimized design of planar balun circuits which operate in the 900 MHz wireless frequency band. The designs are an outgrowth of extensive in-depth computer analysis and fabrication and testing of a multiplicity of circuit realizations. A novel feature of these designs is their compact size which is almost one sixteenth that of conventional quarter wavelength-coupled line designs. Size reduction and excellent coupling are effectively obtained by novel use of discrete capacitors.