China
Africa
Explore chapters and articles related to this topic
Latest Trends in the Field of Printed Antennas
Published in Binod Kumar Kanaujia, Surendra Kumar Gupta, Jugul Kishor, Deepak Gangwar, Printed Antennas, 2020
Radar cross section (RCS) is one of the important parameters in stealth technology which is widely used in military applications. That is why a low value of RCS is necessary in the case of antenna designing. In early days, the reduction in RCS was obtained by conventional methods such the use of ferrite substrate [47], radar-absorbing materials [48] and resistive loads [49]. In the case of RCS reduction in antennas, researchers have to face two major challenges: (i) the reduction in RCS in the complete frequency band and (ii) maintaining the radiation property and reflection coefficient properties of the radiator after making the modifications to the reference antenna. RCS highly depends on the incident angle of EM wave, so maintaining the RCS reduction approximately constant over a wide range of incident angles is another challenge in this field. The use of frequency-selective surface (FSS) is a very effective tool for reducing the RCS value along with maintaining the radiation property and reflection coefficient properties. Boundary conditions on a FSS structure are given as follows [50]: E→inc+E→scat=ZsI^s
Radar and Radar Networks
Published in Hai Deng, Zhe Geng, Radar Networks, 2020
where Pt is the transmit signal power, G is the transmit/receive antenna gain in the direction of the scatterer, λ is the wavelength, R is the range from radar to the scatterer, and σ is the radar cross section (RCS) of the target. The RCS is defined as the ratio of the power reflected back to radar to the power density incident on the target (Mahafza, 2013). When the system losses incurred in various radar components, Ls, and the atmospheric losses, La(R), are taken into account, the radar range equation could be modified as Pr=PtG2λ2σ(4π)3R4LsLa(R)
Targets and Interference
Published in Habibur Rahman, Fundamental Principles of Radar, 2019
The RCS of a target is a measure of its ability to reflect electromagnetic energy in the direction of the radar receiver, and its value is expressed as an area. This reflected energy is dependent on a multitude of parameters such as transmitted wavelength, target geometry, orientation, and reflectivity. The RCS, denoted by the symbol σ, is the area intercepting that amount of power which, when scattered equally in all directions, produces an echo signal at the radar equal to that from the target. Simply stated, the RCS is proportional to the far-field ratio of reflected to incident power density, that is σ=power reflected back to receiver per unit solid angle(incident power density intercepted by the target)/4π.
Wideband Vivaldi Antenna for Reduced Radar Cross Section in Stealth Applications
Published in IETE Journal of Research, 2022
A stealth antenna design should achieve RCS reduction over the entire operating range of frequencies. As the radar signals are directed toward the antenna surface, based on the amount of backscattered energy, the RCS measurements are carried out. The backscattered energy can be suitably reduced by decreasing the perpendicular reflections from the surface of the antenna thus reducing the total RCS of the target. The low observability of DSESAVA is validated by ensuring that the MRCS values are lesser at all the incident angles. Figure 10 shows the MRCS plot at and . The peak MRCS values obtained are −61.317 dBsm for , −74.634 dBsm for , and −76.137 dBsm at , respectively. By the introduction of the two semi-elliptical slots in the reference antenna, the RCS reduction is obtained without any degradation to the antenna's radiation performance.
SAR target recognition using behaviour library of different shapes in different incidence angles and polarisations
Published in International Journal of Electronics, 2018
Mojtaba Behzad Fallahpour, Hamid Dehghani, Ali Jabbar Rashidi, Abbas Sheikhi
Raw data acquisition intends to acquire the RCS in each azimuth position. The RCS is a feature that determines the amount of power returned from a target and is of great importance in the SAR radars. When this amount is high, it means that more power has been returned from the said target to the radar and the target can be seen more brightly in the SAR image (Lin et al., 2017; Shan et al., 2013).