DIRECTIVE DIAGRAMS OE ANTENNA ARRAYS 297 



vertical, or diagonal. A lobe starts as a small bud. it grows in size 

 until it reaches the unit circle, it then becomes dented; the two prongs 

 of the lobe separate more and more until a di\ision into two lobes 

 takes place; then these lobes separate as a new lobe starts to grow 



Fig. 3— Directive amplitude diagram for two antennae (0.6098X, OT) having the 

 minimum area (0.2986) relative to the unit circle 



between them. The additional column of diagrams for a separation 

 of 4X still further illustrates the way in which the lobes multiply 

 and narrow as the separation between the two antennae in increased. 

 The area of the polar directive diagram of an array relative to the 

 area of the unit circle is a measure of the reduction in the energy 

 ratio of random static to signal for that array, assuming that the 

 signal comes from a direction in which the radius vector of the dia- 

 gram is unity while the static is uniformly distributed. All the 

 diagrams for a phase difference of 1/4 period have an area of 1/2. 



