# Introduction to Radar Scattering Application in Remote Sensing and Diagnostics: Review
## 2 Introduction: The Radar System
The doppler amplifier amplifies the signal, which is having Doppler frequency \(f_{d}\). Indicator specifies the information related to relative velocity and whether the target is inbound or outbound, as shown in Figure 2. CW Doppler radars give an accurate measurement of relative velocities. We compare here pulse and CW radar. In the pulse radar system, a modulated pulse signal is used for transmission. Its performance is sometimes affected by the stationary targets. It cannot operate down to zero range. It requires comparatively higher transmitting power. CW radar system uses both modulated and unmodulated CW signals for transmission. Two separate antennas are used for transmission and reception. Unmodulated CW radar measures only the speed of the target but not the distance of the target from the radar. Its performance is unaffected by stationary targets. Because the receiver is ON all times, it can operate down to zero range [4]. Antennas are radiating components, transducers, that turn wave propagation into electrical signals (receiving antenna) and vice versa (transmitting antenna). Antennas in general, and radar antennas, in particular, can be defined by a well-known set of parameters such as effective aperture, directive antenna gain, and power gain [5; 6]. Radars employ a variety of antenna designs, such as dipole, leaky-wave, horn, and patch, often configured to obtain specific patterns and achieve a certain mechanical design [7]. Mostly directive antennas tend to be used to detect weak signals. First, we introduce antennas radiation properties, and from which other antenna parameters are derived in Tables 1 and 2. The electromagnetic wave radiated by the antenna carries electromagnetic power. The radiated power varies in magnitude, depending on both the direction of observation and the distance from the antenna. The electromagnetic power's general pattern is maintained in the far-field, regardless of the distance from the antenna. Therefore, we may introduce a normalized electromagnetic power density that will be independent of the distance from the antenna in the far-field. This is known as the radiation intensity. The radiation intensity is a mathematical description of the angular radiated power distribution in the far field (for a given polarization). In simpler terms, it is how much power is radiated by the antenna in a certain direction in the far field (using proper normalization with respect to the distance from the antenna). To describe mathematically, the radiation intensity, we have to define a way for representing directions. We associate steering angle with all directions. In our manuscript, we investigate the normalized intensity pattern of radar antennas. For this purpose, we take the mathematical formulations and arbitrary parametric values given in Tables 1 and 2. During our numerical test, we investigate the radiation pattern, which is comprised of lobes. These lobes are classified as follows: The lobe containing the direction of maximum radiation is referred to as the major lobe or the main beam. All other lobes are referred to as minor lobes. The main beam often represents the angular sector wherein the majority of the radiated power is intended to lay. The minor lobes, therefore, represent radiation in undesired directions and should be kept as low as possible, as shown in Figures 3 and 4. The simple design and fabrication of the circular dish reflectors allow those antennas to be widely used in microwave applications, and in particular in radar systems [8; 9]. Figure 1: Block diagram of Pulse radar [4]. Figure 2: Block diagram of CW Doppler radar [4]. The far-field radiation pattern for the circular agent antenna of Table 1, computed as the modulus of the aperture factor, is displayed in Figure 3.  
Linear array antennas, such as the one described in Table 2, synthesize narrow directive beams that may be steered, either mechanically or electronically, in many different directions. In particular, electronic steering is achieved by controlling the phase of the array elements.