Netted radar

In this chapter the role of active and passive techniques as a support to homeland security is explored. The essentials of bistatic and netted radar are introduced which enables the relative strengths and weaknesses of these approaches to be outlined. In this way a foundation is provided against which a variety of potential applications may be explored. 

Keywords radar bistatic radar multistatic radar ambiguity function parasitic radar forward scatter Babinet s principle passive coherent location netted radar. 

Multi-static radar is usually combined with the net-centric approach to data exchange. All sensor sites have to be connected by high-throughput, self-configuring data links. The data links should also provide a very stable clock to make all processing coherent, and very accurate time data to synchronize all events in the distributed system. 

In what follows, the above elements will successively be discussed. In section 2, the VIERS-1 equilibrium spectrum will be briefly described, followed by a discussion of the extensions that have been implemented in order to be able to better use it for the present purpose of slick modelling. In section 3, an attempt is made to derive relaxation rates from this spectrum, and the form of the net restoring source term when out of equilibrium is established. In section 4, the radar image modelling will be discussed. Section 5, finally, discusses and summarises the results. 

Mention should also be made of signature adaptation that makes use of negative interference to reduce the probability of detection. In this case, the signature protective layer is adjusted so that negative interference occurs between the radar radiation that is reflected respectively from the outer surface and from the underlying metal, thus causing a black-out of the net reflection from the surface. The reflections in this case need to be adjusted so that 50% is reflected at the outer layer and 50% at the metal surface and so that the phase shift between these reflected radiations becomes half a wavelength at the outer surface. 

Certain deficiencies in the field of security management were proved in the unit using the Checklist Analysis method. Although the prohihition of stay on high spots during radar operation ordered hy directives is observed, the headquarters building is not shielded sufficiently except metallic nets in windows of the central radar attendant s place. The absence of specific protective aids, even if prescribed in internal directives, can be considered to be a major deficiency. 

One principal component of the net-centric BMD system is the Radar-Sensor Service, which publishes radar data that authorized users may subscribe to through a web interface. (These services are analogous to NCDS Sensor Services.) This radar data is consumed by subsequent analytical components, which ultimately present the data as an executive summary to an end user who acts as a decision-maker. Without the data feed from the radar-sensor service, situational awareness for the entire BMD mission is lost. 

There are many applications where the physical properties of a textile substrate are combined with the electrical and shielding properties of polypyrrole. Thus polypyrrole-coated fabrics show excellent dissipation properties. In this way industrial uniforms where explosion-proof conditions or shielding fi om micro-waves are necessary can be fabricated, as well as the use of polypyrrole-coated filters where static charges could cause the explosion of flammable solvents. Other important applications are related to military equipment, as radar-absorbing sheets. The microwave response of those fabrics seems to be ideal for camouflage nets that avoid visual, near-infrared and radar detection. Textile fabrics have also applications in fiber-reinforced composite structures of different resins. 

Fig. 35.13 Camouflage netting system made from Milliken Company s Intrigue ultralight, multispecial (visual, infrared, and radar) camouflage materials.

In the ICO Petri net dialect, time is directly related to transition, which invokes services from the weather radar system (this is the case for transition off Tl on Fig. 9 which switches off the equipment). The duration of each invocation is presented on Fig 13 (each value is coarse grain and depends on the type of weather radar). The 2000-4000ms value corresponds to the time required by the weather radar to scan the airspace in front of the aircraft (two or three scans are needed to get a reliable image). 

Milliken also tried to market ultralight camouflage netting based on Contex to help conceal military equipment and personnel from near-infrared and radar detection, but the company lost a U.S. Army contract for conductive camouflage material in 1997. Despite a recent modest contract with NASA to produce conductive-polymer electromagnetic shielding for the space shuttle, Milliken s research program was in financial jeopardy by early 1998. 

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