A Method of Obtaining a Smooth Pattern on Circular Arrays of Large Diameters with cosn Φ Elements

There are many applications on which one would want to obtain an omnidirectional pattern by mounting many directional antennas around a large structure. If the structure is many wave-lengths in size and if the directional antennas are mounted pointing radially out, then the resulting pattern will usually present very rapid excursions in amplitude with very deep nulls. If one assumes that the directional antennas are of the type cosn ϕ(-π/2⩽ϕ⩽π/2 and zero elsewhere), which are closely approximated by many practical anteunas, then it is possible to smooth out considerably the resulting pattern by pointing the directional antennas tangentially to a circle circumscribing the structure and by properly choosing the radius of the circle. The number of antennas to be uesd determines the value of n.