Optimal inter-element spacing in linear array antennas and its application in satellite communications

As power is not abundantly available on satellites, the power consumed by on-board antennas should he kept low. This can he facilitated by using high-gain directive antennas on the satellite as well as at the p n n d station on earth, so that as little power as possible is wasted while sending and the power is picked up as efficiently as possible while receiving. In the framework of the KULSAT projecf a linear receiving array of dipoles was designed and fabricated to demonstrate an implementation of a phase shifter 111. In this paper, an easy design method is introduced for the optimal linear array i.e. the array with the highest gain. The technique is only exact for isotropically radiating elements, hut can easily he used for an array of dipoles or any other element type with a rotation symmetric radiation pattern around the x ais. The array is then used to scan the beam in the x,y plane (as in Figure 1). The quality of this approximation is discussed for an array of dipoles. For an exact solution or for an asymmetrical radiation pattern an iterative optimization search is needed. Though the array designed here is a ground station transmitting antenna, the results are valid for receiving, ground station, or satellite antennas as well.