A research paper presented by Anirudh Katyal, a UPES student at the International Conference on Recent Trends in Advanced Technology, April 2013

1. A Preliminary Study of Radar: Avionics Prospective
[International Conference on Recent Trends in Advanced Technology April 2013]
Abstract:
Radio Detection and Ranging (RADAR) is a primary microwave system used in Avionics and
Aerospace industry for the detection of various targets for airborne and space borne vehicle
communication and navigation. The basic principle of the system is based on transmission of
electromagnetic signal towards the target and reception of backscattering energy in order to
estimate the range of target and also to estimate the position and speed. The radar antenna
alternately transmits and receives pulses at particular microwave wavelengths (in the range 1 cm
to 1 m, which corresponds to a frequency range of about 300 MHz to 30 GHz) and polarizations
(waves polarized in a single vertical or horizontal plane). This paper focuses on the preliminary
study range equation for the radar system in order to estimate the range of target which is
directly proportional to the radar cross section of target. RADAR System can be classified as (i)
Imaging system, and (ii) non-imaging system. Imaging radar such as Synthetic Aperture Radar
(SAR) system measures the strength and round-trip time of the microwave signals that are
emitted by a radar antenna and reflected off a distant surface or object. For an imaging radar
system, about 1500 high- power pulses per second are transmitted toward the target or imaging
area, with each pulse having a pulse duration (pulse width) of typically 10-50 microseconds (us).
At the Earth's surface, the energy in the radar pulse is scattered in all directions, with some
reflected back toward the antenna. This backscatter returns to the radar as a weaker radar echo
and is received by the antenna in a specific polarization (HH, HV, VV, and VH). These echoes
are converted to digital data and passed to a data recorder for later processing and display as an
image. Given that the radar pulse travels at the speed of light, it is relatively straightforward to
use the measured time for the roundtrip of a particular pulse to calculate the distance or range to
the reflecting object. Higher bandwidth means finer resolution in this dimension. For non-
imaging radar such as Plan Position Indicator (PPI) works on same principle, in this type there is
no conversion of signal information to digital datasets.
In this type, only signal phase and amplitude information are sufficient for the detection of target
from plan view to get the position. The study carried out in this paper is the primary study of
RADAR type and standard range equation for target in aviation industry. The study will be
useful for project related to radar applications in the sector where target detection, identification
of friend and foe, speed estimation is required based by imaging and non-imaging system.
Key Words: RADAR, Imaging and Non-Imaging System, Avionics