Design development and validation of VHF pilot active phased array radar for Atmospheric studies

Abstract

Atmospheric Radar is an important tool to investigate the planetary atmosphere newlinecharacteristics using the remote sensing method. National Atmospheric Research Laboratory newline(NARL), Gadanki (13.45_ N, 79.18_ E) is equipped with Mesosphere Stratosphere newlineTroposphere (MST) radar. MST radar can provide back scattering from the troposphere, newlinelower stratosphere and mesosphere. The MST radar is using Doppler beam newlineswinging (DBS) for getting back scatter signal. In this method a uniform background newlineis considered. Hence, this method could not provide accurate information during the newlinedisturbed atmosphere (convection/precipitation etc.). Therefore, a new method is developed newlineto overcome these limitations, Active Phased Array Radar. In Active Phased newlineArray Radar, the conventional tube-based transmitters are replaced with new solid state newlinetransmitters. This increased the computational power and the introduction of optical newlinecommunication provided the high speed data links. newlineThe pilot active phased array radar is operating at 53 MHz with peak power of 133 newlinekW antenna sizes of about 50 m. The beam width is 6.9_ and the side lobe level of the newlinearray is 16 dB. The master oscillator in the Exciter generate reference clock, to which newlinethe subsystems are locked. RF signal distribution and switching network are used to newlinefeed the pulsed RF signal via 1:19 power divider/combiner unit, which is routed to the newlineTR modules. These signals are combined in the field at 1:19 RF power divider/combiner newlineunit. newlineIn the initial stage pilot active phased array radar is established with solid state 1 kW newlinetransmit-receive (TR) modules, electronic beam steering, interfacing of optical signal newlineand controlling (FPGA Based) of other all subsystems, phase calibration method using newlinefiber optic signal etc. The Active phased antenna constructed with seven segments and newlineeach segment is constructed with 19 elements in hexagonal shape sub-array. 19 TR newlinemodules are connected to 19 ports of each 24 port optical Ethernet switch. newlineA 16 MHz reference clock and reference inter pulse period (IPP) m