Principles of Modern Radar - Volume 2 1891121537

12.2 Electronic Attack 535TABLE 12-1Radar and EW Frequency Band DesignationsRadar Frequency Band DesignationsEW Frequency Band DesignationsBand Frequencies (MHz) Band Frequencies (MHz)HF 3–30 A 0–250VHF 30–300 B 250–500UHF 300–1,000 C 500–1,000L 1,000–2,000 D 1,000–2,000S 2,000–4,000 E 2,000–3,000C 4,000–8,000 F 3,000–4,000X 8,000–12,000 G 4,000–6,000Ku 12,000–18,000 H 6,000–8,000K 18,000–27,000 I 8,000–10,000Ka 27,000–40,000 J 10,000–20,000V 40,000–75,000 K 20,000–40,000W 75,000–110,000 L 40,000–60,000M 60,000–100,000(Notes: HF, high frequency. VHF, very high frequency. UHF, ultra high frequency.)using ES and mission profiles to maintain situation awareness. The aircraft might attemptto avoid detection through low-altitude flight and terrain masking. When the EW systemdetermines that the radar is likely to detect the target, it might apply noise to preventdetection or false targets to delay or deny acquisition. Finally, it may employ noise or deceptivetrack gate pull-off techniques when it perceives that the radar has establishedtrack.The EW community uses a different nomenclature for denoting frequency bands thanthe radar community. Table 12-1 summarizes the radar and EW band designations [5,8].The words technique and waveform are used to describe specific EA approaches andimplementations. There is ambiguity among practitioners regarding the precise definitionsof these terms. For purposes of this chapter, a technique refers to a distinct EA concept orapproach, whereas a waveform refers to a description of the specific temporal, spectral,or spatial characteristics of the EA signal being generated.Another method of countering radar that is sometimes rolled into the EW categoryis the antiradiation missile (ARM). The ARM has a passive radio frequency (RF) seekerthat provides guidance to the missile based on its track of the radar emission. The missilehomes on the radar and disables or destroys it.12.2.2 Jammer TypesThere are two broad categories of jammer designs: noncoherent and coherent. Coherencein this context refers to the ability of a jammer to preserve or reproduce the phase characteristicsof radar waveforms such as the intrapulse modulation of a pulse compressionwaveform or the interpulse phase relationship of a pulse-Doppler waveform. Within thesecategories are an innumerable variety of possible jammer designs. This chapter considerstwo simple, conceptual designs, represented in Figures 12-2 and 12-3. The key differencebetween the two categories is that the noncoherent jammer generates the EA signal throughan independent waveform generator whereas the coherent jammer generates the EA signal