Introduction
Antenna has a significant role in communication systems, RADAR,
biomedical instruments and many other modern applications such as
automated cars. Microstrip patch antenna first introduced in 1970s. This
type of antenna due to ease of fabrication, low profile and miniaturized
size and volume is in demanding state. Microstrip patch antenna can be
built in any shape, for instance: rectangular, circular, triangular and
square [1]. Phased array antenna is designed to steer beam in a
particular direction and suppress ones from undesired directions. A
phased array antenna is consist of three main blocks: radiating
elements, feeding network and phased shifters. Feeding networks are
classified in below categories: constrained feed, space feed and semi
constrained feed. Constrained types are employed in parallel or series
consist of power dividers. [2] Radiating elements can be fed by
microstrip line feed, coaxial feed, aperture coupled feed, and proximity
coupled feed. [3] Phase shifters are used to obtain desired shift by
employing delay lines. Phase shifters usually have two main types: phase
controller phase shifters and switched line phase shifters [4]. In
this paper a rectangular 1x4 array patch antenna designed on ADS
software at a center frequency of 2.4 GHz. The patch antennas were fed
by microstrip line feeds while the feeding network was a parallel
constrained network consist of a 1x4 Wilkinson power splitter. Phase
shifters were designed based on switched line phase shifter to steer for
40o .