Phase-Array Radar and Synthetic-Aperture Radar (SAR) - Research Paper Example

Phase-Array Radar and Synthetic-Aperture Radar Phase-Array Radar: Phased array radar represents a directive antenna that is either formed of individual radiation antennas, or formed by constituents that generate such form of radiation, the nature and route of which are obtained by the relative stages and amplitudes of the currents reflected at the particular components. The relative phases are capable of variations, hence allowing steering of the radar beams. Applications in radars are most common particularly in which the beams need to be shifted from one place to another within the space.

It also helps in obtaining data that require flexibility in the collection of the data (Skolnik, 2007, p.278). The use of phased array can be made in radar applications for airborne fighter or attack radar applications. This is particularly possible through phased array radar that can be electronically steered (Skolnik, 2003, p.649). The concept behind phased array radar is that it makes use of the signal phases through its electronic controls. The phases are obtained at specific components of the array leading to generation of constructive interference in a path that is preferred for the positioning of the beams.

Mechanical activities are not required in the process. Depending on each individual pulse, the radar beam can be steered, the time interval of such steering generally being 0.001s. The steering can be obtained in any desirable direction and in different angles. The flexibility of the beam steering is unlike other mechanical radars thus making the phased array radars unique and different from others. The stress generated on the pedestals, motors, and other parts of the radar can be reduced through methodical scanning of the radars following an uninterrupted model (Committee on the Evaluation of the Multifunction Phased Array Radar Planning Process, 2008, p.19). Synthetic-Aperture Radar: Synthetic aperture radar is a particular form of implementing the system of imaging radar.

This system makes use of the platform of the radar and the processing of signals is made specific leading to generation of images that are of high resolution. In this system the resolution along the tracks of the radar beams are enhanced with the use of Doppler frequency analysis of signals that are obtained from radar coherently travelling along the track. The primary concept of the synthetic aperture radar is that with the use of this radar system, the signals get integrated from the area of the scatter of the signals till the moment the scatterer stays along the beam antenna (Zyl, 2011).

The working of the synthetic aperture radar can be represented through the following figure (ASAR Image Orthorectification, 2013): The angular measurement of azimuth is involved in this system. Depending on the measurement of the traces along the azimuth angle, the clarity of the resolution would be obtained. The narrower the width, the finer would be the resolution. The width of the footprint can be determined by the following equation (Noorizadeh, 2010): ?ra ? R?B = R?/D Where, ra represents the resolution obtained from the real aperture of the antenna, D.

R represents the series between the midpoint of the trail and the antenna, and ? is the wavelength of the frequency of the signal that has been transmitted (Noorizadeh, 2010). Synthetic aperture radar systems make use of advanced processes of digital signaling in order to take advantage of the movements that are ahead of the platform. This allows synthesizing a large aperture for the antenna thereby increasing the resolution of the range. However the antenna apertures do not increase in sizes that can be considered as unrealistic, thus benefitting the process of imagery through the use of synthetic aperture radars (Noorizadeh, 2010).

Synthetic aperture radars can be used on oceans for tracking illegal or accidental spills that are done by men, for wave forecasting, and monitoring of the levels of ice. On the land, the system can be used for passing through cloud covers and determining the uses of the lands for agriculture and forestry, for detection of the geological and geomorphological features of a land to understand its suitability for use, for reference of other imageries on satellites to make them highly precise, as well as for realizing the aftermaths of floods in order to determine the measures necessary to be considered for recovery of the regions (The Applications of SAR Data – An Overview, 2013).

References ASAR Image Orthorectification (2013). EOSNAP. [Online]. Retrieved on 27 June 2013 from: http://www.eosnap.com/earth-observation/asar-image-orthorectification/ Committee on the Evaluation of the Multifunction Phased Array Radar Planning Process (2008). Evaluation of the Multifunction Phased Array Radar Planning Process (Google eBook). Washington, D.C.: National Academies Press. Noorizadeh, S. (2010). An Introduction to Synthetic Aperture Radar Resolution. 123seminarsonly. [Online]. Retrieved on 28 June 2013 from: http://www.

123seminarsonly.com/Seminar-Reports/014/30937362-An-Introduction-to-Synthetic-Aperture-Radar-Resolution.pdf Skolnik, M.I. (2003). Intro to Radar Systems 3/E. New York: Tata McGraw-Hill Education. Skolnik, M.I. (2007). Intro to Radar Systems 2E (Sie). New York: Tata McGraw-Hill Education. The Applications of SAR Data – An Overview (2013). ESA. [Online]. Retrieved on 28 June 2013 from: http://earth.esa.int/applications/data_util/SARDOCS/ Zyl, J.J. (2011). Synthetic Aperture Radar Polarimetry. New Jersey: John Wiley & Sons.