Abstract: A pseudo-coaxial vertical transition (10) includes a substrate (16). A bump array is disposed in a substantially concentric bump pattern upon the substrate (16) for simulating a pseudo-coaxial vertical electromagnetic wave propagation. The bump array is formed from a centrally disposed bump (32) having a predetermined bump diameter, and a plurality of at least five ground bumps (36) substantially equi-distant and circularly disposed about the centrally disposed bump (32). The predetermined bump diameter and a bump spacing of the centrally disposed bump are determined in relation to the plurality of ground bumps and a dielectric constant of air for providing a characteristic impedance.