In this chapter and in the frame of long-wavelength Heisenberg model, simple magnonic mono-mode circuits are designed to obtain transmission stop (pass) bands where the propagation of spin waves is forbidden (allowed). These simple devices are composed of infinite one-dimensional mono-mode waveguides (the backbone) along which symmetric or asymmetric loops are grafted. These circuits are usually mono-mode when the lateral dimensions of the conducting wires are small as compared to the magnon wavelength. Their production utilizes the most advanced surface technologies and represents one of the most important future challenges. In all these circuits, the interfaces between the different wires out of which the circuits are made of play a fundamental role. These structures can be arranged from very simple structures (two resonators) mimicking the classical analog of Fano resonances and electromagnetic-induced transparency (see Chapter 2), to periodic structures showing the possibility of existence of large gaps in their band structure. All such circuits exhibit a variety of interference effects in their transport properties. Analytical results for the transmission and reflection properties of such circuits are discussed, as a function of the frequency of the excitations and the physical or geometrical properties of the circuits. Emphasis in this chapter is placed on the network creations within the Green’s function method. These magnonic circuits may be used for the design of integrated devices such as narrow-frequency optical or microwave filters, high-speed switches, multiplexers, storage devices, and so on.