T-junction and other microstrip discontinuities, up to radiation frequencies, as joining of open-circuits

The beam-forming network (BFN) of an antenna array, say of patches, is composed of T-junctions and other discontinuities linking sections of, say, microstrip lines. For easy design of the BFN, therefore, it is good to have a set of accurate, simple and insightful, and flexible equivalent circuits for these junctions and discontinuities. Heuristic equivalent circuits with curve-fitting formula from numerical solutions, are accurate but frequently requires 10 or even more arbitrary coefficients for each discontinuity. Arbitrary coefficients reduce the insights useful for the design trade-offs. This work overcomes the problem by reducing the discontinuities into the joining of just one equivalent circuit type - the simple open-circuit half-line, even at high RF frequencies.