Cylindrical Phased Array
Figure 1: L-IESA NR-IFF made by Intersoft Electronics Ltd.
Cylindrical Phased Array
A cylindrical phased array (CPA) consists of a flat phased array wrapped around a vertical cylinder. It can be used for radar applications and typically has an element-to-element spacing of nearly half the wavelength, like planar phased array antennas.
For a two-dimensional scanning radar, all the lying upon each other antenna elements are combined into a group with mutually constant phase relationships. This can also be a constellation, for example, as used in a Large Vertical Aperture, to generate an approximate cosecant squared pattern vertically.
To rotate the antenna radiation pattern in the horizontal plane, only those vertical antenna groups that are within a sector of 90° are excited. The circular curvature of the active antenna array is electronically compensated by phase shifters so that the radiation is the same as with a flat-distributed phased array antenna. A swivel to the right is achieved by switching off the vertical group on the far left and switching on an additional group on the far right. This sector is thus electronically shifted in a circle so that the radiation is the same as with a mechanically rotating antenna.