Compact tuneable single and dual mode ferrite left-handed coplanar waveguide coupled line couplers

For the first time, single and dual mode novel left-handed coupled line couplers implemented on ferrite substrates are reported. Both of the proposed couplers demonstrate novel characteristics of coupler operation with properties of tunability and non-reciprocity, which have not been demonstrated before. The proposed couplers are realised in a left-handed coplanar waveguide configuration, constructed using interdigital capacitors and various types of planar shunt inductors. The performance of the couplers has been studied theoretically and verified numerically. The single mode tuneable coupler demonstrates a coupling level as high as 4 dB with a maximum isolation level better than 25 dB. The dual mode tuneable coupler exhibits non-reciprocal operations with a near-zero dB coupling level and a maximum non-reciprocal isolation level of more than 30 dB. Moreover, both the couplers have very compact sizes: 10.32 mm times 19.8 mm for the single mode coupler and 10.2 mm times 19.8 mm for the dual mode tuneable coupler, respectively.