A Broad Band Patch Antenna Used as Auxiliary Load for Measuring Multi-port Device with 2-port VNA at W-band

This paper presents a simple technique for characterizing multi-port devices. It gives a fast and efficient measurement of the scattering S-parameters of the multi-port device under test (DDT) by measuring 2 of the N ports while other N -2 ports being terminated by broad band antennas as substitution to 50
$\Omega$
loads to minimize reflection. This method is applied to the characterization of a 4-port branch-line quadrature hybrid coupler centered at 100 G Hz, where direct 4-port measurement are not equipped. Widely available post processing algorithms are then applied which reconstruct the
$\mathrm{C}_{2}^{\mathrm{N}}$
sets of 2-port measured S-parameters into a N port S-parameter for testing purpose. The reconstructed S-parameters match the 4-port simulation well especially in terms of amplitude and phase of the transmissions at both output ports.