Microstrip-Slot Coupler Design-Part I: S-Parameters of Uncompensated and Compensated Couplers

Using the even-odd mode analysis of four-port networks with double symmetry, the scattering parameters of the microstrip-slot coupler are derived from the even- and odd-mode parameters of the coupler cross section. The uncompensated coupler and the coupler compensated by extending the slot fines are treated and design specifications are given covering the compensation slot lines. A comparison with experimental data will be given in Part II.