Principles of Modern Radar - Volume 2 1891121537

12.4 EP Overview 553100FIGURE 12-8Jammer receivedpower example.Jammer Received Power (dBm)−10−20−30−40−50−60−70−80−90EW ReceiverSensitivity(detectionthreshold)ReceivedPower fromRadar MainlobeReceivedPower fromRadar Sidelobe−100110010Range (km)12.3.8 Jammer Received Power ExampleTo illustrate the application of the jammer received power computation, continue theexample from Table 12-2. We will consider only the ESJ (not the SOJ), and we willcompare the power the ESJ receives in the radar main lobe with the power it receives inthe radar sidelobe. Suppose the EW receiver has a sensitivity of –60 dBm, correspondingto the minimum detectable signal power present at the receive antenna port. Figure 12-8plots the received power from the radar main lobe and sidelobe as a function of range andalso marks the –60 dBm detection threshold in the EW receiver. The EW receiver is ableto detect the radar beyond 200 km in the main lobe but not until approximately 7 km in thesidelobe. This corresponds to the 35-dB difference between the main lobe gain, 30 dBi,and sidelobe gain, assumed to be –5 dBi, as per Table 12-2. Thus, it would not be practicalfor this EW system to be employed in the radar sidelobes, unless very short-range SIJroles are envisioned.12.4 EP OVERVIEWElectronic protection is intended to reduce the effectiveness of an opponent’s EA or EScapability. Many radar design features that are motivated by the need to improve performanceunder stressing target, clutter, and electromagnetic interference (EMI) conditionsalso provide inherent resistance to EA. Examples include low radar sidelobes, auxiliaryantenna blanking and cancellation channels, monopulse angle measurements, pulse compression,wide dynamic range, Doppler processing, and frequency diversity. These designfeatures are always in effect, and they provide optimum performance under both naturaland EW environments. Such design features can be described as providing intrinsic EP.In contrast, some EP features are only enabled under suspected EW conditions. Thesefeatures can be described as responsive EP. Responsive EP does not in general provide