An improved antenna configuration is disclosed for a fully duplex portable radiotelephone that is normally operated in the nearly horizontal position next to the user's ear and mouth. A notch antenna is provided in the bottom portion of the portable radio transceiver parallel to the major longitudinal axis of the housing. The notch aperture is cut in the conductive radio housing at a transverse angle to the major face plane of the radiotelephone to form a notch antenna which radiates predominately vertically polarized E-field waves when the transceiver is positioned such that the major longitudinal axis of the radio is approximately 30 degrees to the horizontal. The notch is an effective quarter-wavelength long and is dual-fed from a pair of coaxial cable transmission lines near the shorted end of the notch.