Size-reduction balanced UWB BPF design using meander slotline and its mirror structure with the microstrip feed

The contribution of this work is to propose a size-reduction design of a balanced UWB BPF using a meander slotline together with its mirror structure. The size reduction is accomplished by meandering the slotline. The proposed circuit is excited by a vertically oriented feeding microstrip. The meander slotline combined its mirror one exhibits a wideband response as well as the one of an ordinary slotline. However, the former together with the microstrip feed, which perfectly preserves the structural symmetry, has a much smaller circuit size. This structural symmetry of the circuit renders itself suitable in the balanced circuit design. Thus, a smallest balanced UWB BPF in the slotline-alike structure category is realized.