radar minimum range equation

radar range equation represents the physical dependences of the transmit power, which is the wave propagation up to the receiving of the echo signals.

Specifically, if the ground plane deviates from a flat surface then the reinforcement and i.e. if the power radiated is redistributed to provide more radiation in one direction, The standard form of Radar range equation is also called as simple form of Radar range equation.

This effect is called

without dispersion.Figure 1: Nondirectional power density diminishes as geometric spreading of the beam.Since a spherical segment emits equal radiation in all direction (at constant transmit power)

Minimum detectable signal (Pmin) depends on receiver bandwidth (B), noise figure (F), temperature (T), and required signal-to-noise ratio (S/N).

Formula: R Max = ((P t *G* S * A e) / ((4 * PI) 2 * P Min)) It is expressed as “J/S” and, in this sec tion, is always in dB. A typical value of 1 µs pulse width of a short range radar corresponds The distance between Radar and target is called Range of the target or simply range, R. We know that Radar transmits a signal to the target and accordingly the target sends an echo signal to the Radar with the speed of light, C.

then this results in an increase of the power density in direction of the radiation.

electromagnetic waves propagate under ideal conditions without disturbing influences. A fine-grained lobing structure is often filled in by irregularities in the ground plane. destruction pattern resulting from the ground reflections breaks down. Since Another equation, which will not be derived here, describes the antenna gain All quantities that influence the wave propagation of radar signals were taken into account at this equation. We know that power density is nothing but the ratio of power and area.

First, the radar equation is extended by including the An extended but less frequently used form of the radar equation considers additional terms, Furt… Therefore, the power density, Pdddue to directional Antenn… In practice, a some further considerations are necessary.The smallest received power that can be detected by the radar is called An application of this radar equation is to easily visualize how the performance of the radar sets influences the achieved range.All considerations, when calculating the radar equation, were made assuming that the

When factoring EA into the radar equation, the qua ntities of greatest interest are “J-to-S” and Burn- Through Range.

with longer waveforms suffer a relatively large minimum range, notably Before we attempt to use the radar equation in the practice for example to determine the efficiency of radar sets, Assume that the minimum detectable SNR at the receiver of a monostatic radar operating at 1 GHz is 13 dB. Figure 1: Nondirectional power density diminishes as the geometric spreading of the beam.Figure 1: Nondirectional power density diminishes as the geometric spreading of the beam.First, we assume, that electromagnetic waves propagate under ideal conditions,

In general, Radars use directional Antennas.

Use the radar equation to determine the maximum detectable range for a target with a nonfluctuating RCS of if the radar has a peak transmit power of 1 MW. and the height of the antenna. The target detection isn't only dependent on the power density at the target position, Range. Avoidance of lobe effects is one of the prime considerations when selecting radar location Maximum Unambiguous Range; Minimum Range; Now, let us discuss about these basic terms one by one.

The power PE returning to the receiving antenna is given by the radar equation, depending on the transmitted power PS, the slant range R, and the reflecting characteristics of the aim (described as the radar cross-section σ). During the transmitting time the radar cannot receive: (e.g. Time Delay Ranging • Target range is the fundamental quantity measured by most radars.

like the Earth's surface but does not classify receiver sensitivity and atmospheric absorption.The trigonometric representation shows the influence of the Earth's surface. However, radars An Airbus offers more radar cross-section than a sporting aircraft at the same flight situation. Targets at a range equivalent to the pulse width from the radar are not detected. It is obtained by recording the round trip travel time of a pulse, TR, and computing range from: where c= 3x108m/s is the velocity of light in free space. The accuracy of the radar range equation is only as good as the input data. In this case, the reflected power Since the echoes encounter the same conditions as the transmitted power, Of course, in reality, radar antennas aren't “partially radiating” isotropic radiators. Figure 4: A vertical pattern diagram with influences of ground reflectionsFigure 4: A vertical pattern diagram with influences of ground reflectionsFigure 4: A vertical pattern diagram with influences of ground reflectionsIncreasing the height of the antenna has the effect of making finer the lobing pattern. However, radars with longer waveforms suffer a relatively large minimum range, notably pulse compression radars, which can use pulse lengths of the order of tens or even hundreds of microseconds. the power density yielded at the receiver The effective antenna aperture arises from the fact that an antenna suffers from losses,

Beyond this the reflecting area depends on the design, surface composition and materials used.Simplified a target can be regarded as a radiator in turn due to the reflected power. A narrow bandwidth receiver will be more sensitive than a wider bandwidth receiver. but also on how much power is reflected in the direction of the radar.

Monostatic pulse radar sets use the same antenna for transmitting and receiving. “J-to-S” is the ratio of the signal strength of the ja mmer signal (J) to the signal strength of the target return signal (S).

At the known sensibility of the radar receiver, the radar equation determines the achieved by a given radar theoretically maximum range. • Rmax– the maximum range of the radar • Pt– average power of the transmitter • G – gain of the transmit/receive antenna • λ – wavelength of the operating frequency • s – radar cross-section of the target • Smin– minimum detectable signal power 5 1.2 Units of the equation 4 min 3 2 2