Evaluation of the influence of frequency on effectiveness of microstrip device miniaturization by means of artificial transmission lines

摘要

The influence of central frequency on effectiveness of branch-line coupler miniaturization was investigated. Miniaturization consists in substituting the microstrip transmission line with an equivalent artificial transmission line. Several couplers with different central frequency were designed, modeled and manufactured. The frequency characteristics of the designed devices and couplers with traditional topology were measured and analyzed. The comparison of the area occupied by the directional coupler with the traditional topology and compact one with artificial lines is carried out as well. It is shown that the benefit in reducing the coupler size is much greater than the loss caused by the reduction the operating frequency band if the same substrate is used.