An electrical connector including a lead frame assembly of a first dielectric material that includes a pocket filled with a second dielectric material. A first ground reference, which may be either a ground contact or conductor or a virtual ground defined between signal contacts of a differential signal pair, extends in the first dielectric material and has a first physical length. A second ground reference having a different physical length than the first length extends in the first dielectric material and also through the pocket. The combination of the length of the second ground reference through the pocket along with the difference in the dielectric constants associated with the first and second dielectric materials, provides for equalizing or matching the electrical lengths of these two references having different physical lengths. This may aid in reducing slot-line mode of a co-planar waveguide. The cross-sectional size of the second reference within the pocket may be altered to provide uniform impedance along the length of the second reference as well as an impedance matched to the first conductor.