Stripline crossover

A suspended stripline crossover structure comprising first and second suspended striplines (32, 34) extending in different directions and disposed between first and second ground planes (36, 38), and a cross over region (30) in which the first and second suspended striplines cross over, but are spaced apart, the cross over region including a ground plane structure (40), which defines a third ground plane (42) disposed between the first and second suspended striplines, and which is electrically coupled to the first and second ground planes by capacitive couplings, in the form of leg extension portions (43-46) of the ground plane structure having flat portions (48, 50) engaging dielectric films (56) located on the first and second ground planes, such that at a frequency of operation, the capacitive couplings provide low impedance connections between the third ground plane and the first and second ground planes.