Disconnectable microstrip to stripline transition

Claim 1

In combination: (A) a mechanically rigid chassis, (B) a first electronic circuit attached to said chassis employing a microstrip transmission line of a given characteristic impedance (Z), comprising a first dielectric layer having a first ground plane, and a first portion of a first conductor having a first width, (c) a second electronic circuit attached to said chassis employing a stripline transmission line of said given characteristic impedance (Z), comprising a second dielectric layer having a second ground plane, a third dielectric layer having a third ground plane, said third dielectric layer being disposed in parallel proximity to said second dielectric layer, and having a rectangular extension with ground plane projecting beyond said second dielectric layer; a second conductor of finite width supported between said second dielectric layer and said third dielectric layer and supported upon said rectangular extension, a first portion of said second conductor having a first width selected to achieve said characteristic impedance (Z); said electronic circuits, when attached to said chassis, being positioned to provide a short air gap between the dielectric layer and ground plane of said microstrip transmission line and the rectangular extension of the third dielectric layer and third ground plane of said stripline transmission line for convenient interconnection, and (d) demountable transitioning means comprising (1) a second portion of said first conductor adjacent said pair gap having a second width greater than said first width, to create a first equivalent low impedance shunt capacitance localized along said second portion, (2) a flexible flying lead bonded to the second portion of said first conductor, extending across said gap and overlapping said second conductor, said flying lead having a width across said air gap selected to exhibit an equivalent high impedance, series inductance localized along said air gap, (3) a second portion of said second conductor adjacent said air gap, having a second width, greater than said first width, to create a second equivalent low impedance shunt capacitance localized along said second portion, the combination of said first and second equivalent shut capacitances and said series inductance providing a desired pass band, and (4) means to facilitate demounting said transition and to suppress the undesired waveguide mode in the transition comprising (a) a fourth removable rectangular dielectric layer which forms an electrically continuous extension of the second dielectric layer coextensive with the rectangular extension of said third dielectric layer and (b) conductive means comprising (i) a first removable conductive member which forms an electrically continuous extension of said second ground plane to said air gap, and (ii) a pair of vertical conductive members interconnecting said first removable conductive member and said third ground plane to form a short rectangular waveguide section containing said fourth dielectric layer and the rectangular extension of said third dielectric layer and ending at said gap, said vertical conductive members defining side walls of a waveguide section, the dimensions of which suppress the waveguide mode by being below cut-off through said desired passband, said fourth removable dielectric layer, when in position, pressing said flexible flying lead into electrical contact with said second conductor to connect said first and second electronic circuits together.