“…Conventional single band BLCs are implemented using quarter wavelength long branches resulting in spurious responses only at the odd harmonics of the fundamental frequency [1]. In contrast, multi-band designs are implemented by adding additional stubs [4] and half-wavelength sections [5] to the conventional structure, modifying the coupled-lines structures [6] or some other unique BLC structures [7,8], by port-extension techniques [9][10][11], etc. Over the years, numerous works have been reported on different aspects of dual-band coupler performance, for example, bandwidth control [12] and enhancement [13], miniaturization [14], wider band-ratio support [15], arbitrary port impedance [11], and arbitrary power division [9-11, 16, 17].…”