“…Dual-mode filter was firstly proposed using a dual-mode ring resonator by Wolff [1]. The dual-mode property has been particularly investigated and developed for single [2,3] or dualband [4,5] bandpass filters to obtain high frequency selectivity near passbands by using one or more transmission zeros on the low or high side of passbands. In [6], a cross-slotted patch resonator is successfully developed to demonstrate the simultaneous size and loss reduction, and further to build a novel dual-mode bandpass patch filter by suitably selecting the unequal cross-slot lengths along the two orthogonally diagonal planes.…”