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BELL SYSTEM TECHNICAL JOURNAL 



posed of an array of 16 quarter wave dipoles spaced 0.1 wave-length 

 in front of a flat metal refletlor. All feed system lines and impedance 

 matchinj,' (Icxiccs arc made uj) of coaxial transmission line sections. The 

 array is divided into four quarters, each being fed from the lobe switching 

 mechanism. This division is required to i)ermit lobe switching in both 

 horizontal and vertical planes. The function of the lobe switching mecha- 



3C'M Anti-.\irciaft Radar Antenna. 



nism is to introduce a particular phase shift in the excitation of the elements 

 of one half of the antenna with respect to the other half. The theory of 

 this tyjjc of lobe switching is discussed in section 11.1. The antenna beam 

 spends a])j)roximately one quarter of a lobing cycle in each one of the four 

 lobe positions. Each of the four lobe positions has the same radiated field 

 intensity along the antemia axis and therefore when a target is on axis 

 equal signals will be received from all four lobe positions. 



