Whispering gallery modes supported by open circular dielectric cavities are embedded into a non-parametric 2-D frequency domain hybrid coupled mode theory framework. Regular aggregates of these cavities, including straight access channels, are investigated. The model enables convenient studies of the guided-wave scattering process, the response of the circuit to guided wave excitation. Transmission resonances can be characterized directly in terms of resonance frequency and linewidth by computing supermodes of the entire composite circuits, comprising both cavities and bus waveguides. Examples of single ring-and disk-filters, a coupledresonator optical waveguide, and a three-cavity photonic molecule in a reflector configuration allow the approach to be assessed.