Effects on scan blindness of full and partial crosswalls between notch antenna array unit cells

Endfire slotline notch antennas are attractive candidates for use as printed antenna array elements due to their broad bandwidth capabilities. These elements can be difficult to array because scan blindnesses may occur unexpectedly. One class of these blindnesses, an E-plane scan blindness, was explored by Schaubert and Aas (see IEEE Antennas Propagat. Soc. Symp. Dig., p.1612-1615, 1993). The referenced article gives graphs for the predicted blindness angle. A trough is formed by the metallized dielectrics and the ground plane. One possible explanation of this phenomenon is that the interelement phasing required to steer the beam to the blind angle excites a surface wave, which propagates down the trough. All of the power, instead of radiating into space, is guided across the array face, causing the blindness. This paper presents simulated results of the effects of blockading the trough with an electrically conducting cross wall (a wall perpendicular to both the metallized dielectric and the array face, as shown) or using portions thereof. The full cross wall is shown to eliminate the blindness. Interesting results which arise when partial walls are placed between unit cells are also presented. One set of results suggests a new modification to the notch array one in which the active element pattern provides far out sidelobe suppression.