Radar cross section antennas

I. P. Theron, E. K. Walton, and S. Gunawan, Compact range radar cross-section measurements using a noise radar , IEEE Trans. Antennas Propagat., vol. 46, pp. 1285-1288, Sept. 1998. 

Radar is the acronym for radio detection and ranging1. This means that electromagnetic waves are used to measure the distance between a radar antenna and an obstacle. The simple form of the radar equation expresses the maximum radar range Rmax in terms of the key radar parameters and the radar cross section of the target. 

The radar cross section of the antenna mode component is now defined as an area da t so large that the power density <4>ant associated with the fictitious plate is the same as the power density associated with the antenna mode component that is, we set... 

Substituting (2.5) and (2.7) into (2.6) yields the radar cross section of the antenna mode ... 

Expression (2.8) will in general not constitute the entire RCS of an antenna. In fact, it is only a component of the total radar cross section, which implies that there may be something else. This is usually called the residual (or structural) component a res- It was defined earlier as whatever must be added to the field associated with a am as given by (2.8) in order to obtain the field associated with the total antenna RCS, that is. 

This definition has been known at least since World War II [55] and has been widely quoted eversince [37, 38, 56-58]. What is more, it has often been implied that this class of antenna represents the ultimate as far as low radar cross section is concerned and, consequently, should be treated with great respect ... 

It was pointed out in Chapter 2 that arrays possess unique features from a radar cross section point of view. To reduce the RCS outside the operating band of an antenna in general, a bandpass radome is often placed in front of it (see Chapter 2, Fig. 2.1). In the case of an array we recall from Chapter 2 that a low RCS is obtained when the terminal reflection coefficient is low in other words, the bandwidth of the array should ideally exceed that of the radome. Furthermore, due to the high price tag of arrays in general, it is desirable to pass on as much information through them as possible. Thus, we shall in this chapter consider the principles for broadband arrays, which is of interest to the communication community. 

In this book, Ben treats a number of subjects related to antennas and both their intended usage as transmission or reception devices, as well as the important (these days) radar cross section (RCS) that they can contribute. A constant theme behind the presented results is how often investigators approach the problem with no apparent understanding of the real-world factors that bear heavily on the practicality and/or quality of the result. He takes issue with those who have become so enchanted with high-powered computers that they simply feed the machine some wonderful equations and sit back while it massages these and optimizes a result. Sad to say, Ben has been able to document all too many examples to prove his point. 

Mr. W. Bahret was with the United States Air Force but is now retired. From the early 1950s he sponsored numerous projects concerning radar cross section of airborne platforms—in particular, antennas and absorbers. Under his leadership grew many of the concepts used extensively today—for example, the metallic radome. In fact he is considered by many to be the father of stealth technology. 

J. Appel-Hansen, Accurate Determination of Gain and Radiation Patterns by Radar Cross-Section Measurements, IEEE Trans. Antennas Propag., Vol. AP-27, No. 5, September 1979, pp. 640-646. 

Figure 7. Cross sectional view of transmitted electromagnetic signal generated from ground penetrating radar antenna transceiver.

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