Practical Active Phased Array Antenna in the Assembly of Sub-arrays with Partial Drive Technique

A conventional active phased array antenna (APAA) for a military purpose is composed of modules each of which includes a radiator, a high power amplifier (HPA), a low noise amplifier (LNA), a phase shifter and combiners on a printed circuit board (PCB). Therefore, such a APAA is thicker than the longitudinal size of the PCB. Several attempts of planar APAAs were proposed to overcome the disadvantages [1][2]. A thinning technique or a sparse array were to reduce the element number [3]. Another attempt is to use the identical elements and electronics in realizing a desired field distribution on an array aperture [4]. Our project aims to drastically reduce the cost and improve handling capability of an APAA for practical applications [5] [6] [7]]. The key technologies are as follows: (1) Partial drive technique of radiators [8]. (2) Switch of Micro ElectroMechanical System at radio frequency (RF-MEMS). (3) Amplifiers of Monolithic Microwave Integrated Circuit (MMIC). (4) Integration of an antenna in flat layers. By partial drive technique, the number of driven elements can be lessened to a half of the whole, as is quite effective to feeding simplification and eventually cost reduction. Also in integrating a large array antenna, it is effective to divide the antenna into sub-arrays of the same configuration from the viewpoint of manufacturing, test and inspection. On the other hand, the grating lobes in the partial drive case would be larger than those in the full drive case. In order to prevent the grating lobe growth, a randomizing technique was proposed [9]. But a randomized array antenna tends to be difficult to divide into sub-arrays with identical shape and configuration. This paper presents a new design concept of sub-arrays which can prevent the increase of grating lobes due to partial drive technique. The availability is confirmed by theoretical analysis and simulation.