A dual-mode resonator comprises a dielectric substrate having a region
divided into four quadrants, and a ring resonator forming quadrangularly
symmetrical configurations within the four quadrants of the region. The
symmetrical configurations may be formed from folded sections of the
resonator, so that parallel lines with opposite currents that cancel to
minimize the far-field radiation of the filter structures. The
symmetrical configuration can also be meandered, so that opposite
currents in parallel line segments within each meander and the line
segments that interconnect the meanders cancel to minimize the far-field
radiation of the filter structures. One resonator can be used in a
two-pole dual-mode filter structures, or multiple resonators can be used
in more complex dual-mode filter structures. The filter structures also
include input and output couplings with capacitors and transmission lines
that directly connected to the resonator to provide a point of contact,
which more accurately represent ideal lumped element capacitor
connections from computer modeling.