%0 Journal Article
%T A Compact and Wideband Coupled-Line Coupler with High Coupling Level Using Shunt Periodic Stubs
%A R. Keshavarz
%A M. Movahhedi
%J Radioengineering
%D 2013
%I Spolecnost pro radioelektronicke inzenyrstvi
%X A wideband microstrip forward-wave coupled-line coupler with high coupling value is presented. Compared with the conventional edge-coupled microstrip forward-wave coupler, this symmetrical structure, consisting periodic shunt stubs between the two coupled-lines, achieves wider operating bandwidth and larger coupling level. To characterize this structure, the equivalent circuit model is established and verified by measurement and full-wave results. The designed and fabricated prototype is a 0-dB forward-wave coupler with 0.6 mm stub length. This coupler exhibits a coupled amplitude balance of +/-2 dB, good matching (15dB) and at least 15dB isolation between adjacent ports over a wide bandwidth of 66% from 2 GHz to 4 GHz centered at 3 GHz. The coupled-line length and width of the proposed structure are approximately lambda_g/2 and lambda_g/13, respectively, which makes it more compact than the conventional forward coupled-line couplers.
%K Coupled-line couplers
%K periodic structures
%K forward-wave couplers
%K shunt stubs
%K wideband microwave devices
%U www.radioeng.cz/fulltexts/2013/13_01_0323_0327.pdf