Improved method of reactive loading for miniaturisation of transmission lines with minimal degradation in performance

This study presents an improved method of constant reactive loading for the miniaturisation of quarterwavelength transmission lines. The method provides an optimum location for loading, which maintains the electrical characteristics before and after miniaturisation. Therefore circuits based on transmission lines can be miniaturised with negligible deterioration in performance. This simple yet highly effective method is especially attractive for popular multi-section circuits, in which a number of sections are cascaded for wider bandwidths. Experimental results of various Chebyshev multi-section impedance transformers not only verifies the effectiveness of this method in bandwidths as large as 99% with a size reduction of more than 55%, but also demonstrates the method's flexibility of design.