Radar Bands

The following are radar-band types, frequencies, and typical applications (1) L-band (1400 megahertz) used for early-warning systems ... 

Radar band Radar wavelength fcml Incidence angle f°l Bragg wave-number Trad m1 1 Maximum damping dB]... 

First, to avoid potential interference to communications and radar bands, the entire microwave spectrum is not readily available for chemistry. By international convention the frequencies 915 + 25 MHz, 2450 + 13 MHz, 5800 + 75 MHz, and 22125 + 125 MHz have been assigned for industrial and scientific microwave heating and drying applications. For synthetic chemistry, equipment operating at 2450 MHz, corresponding to a wavelength of 12.2 cm, is used almost exclusively. 

Only for particular molecules, e.g. ammonia because of its strong lines in the 20-40 GHz region, or water at 22 GHz because there is no other line until 183 GHz, would spectral considerations force the worker to lower frequencies. The 20-40 GHz band is also attractive, however, because of the cheap sources and low-noise semiconductor detectors, manufactured for movement sensors and short-path wireless links. The projected automobile collision-avoidance radar systems will make cheaper sources and detectors available for the 60-70 GHz region within the next few years. The 60 GHz across-office circuits for wireless data links could provide useful narrow-band sources for oxygen determination. The 35 GHz and 94 GHz close-range radar bands provide a useful reservoir of components and sources for the potential manufacturer of MMW spectrometers. 

It is not always easy to determine the best radar frequency band to use, unless a parametric study is performed to determine performance as a function of frequency. The typical radar bands (L-, S-, C-, X-,... 

TABLE 17.2 Double Sideband Noise Figure for Various Radar Bands, Achievable with Low-Noise RF Amplifiers... 

Radar band L-band S-band C-band X-band Ku-band Ka-band W-band... 

Oscillator phase noise is one of the major contributors to this effect. Figure 17.17 shows the phase noise that can be expected from oscillators at a variety of common radar bands. The spectral spreading shown, modified by sampling effects and range ambiguity effects, is a measure of the subclutter visibility that can be achieved. 

The producer of these maps is the Ice Center AARI. They are compiled on the basis of satellite information (in the visible, infrared and radar bands) and reports from the Arctic and coastal stations same like ships. The data are collected during the period of 2-5 days and after averaging are issued every Thursday which is the reference date. An example name of file is aari bar YYYYMMDD pl a.ZIP (which contains SHP, DBF, SHX, PRJ files) elaborated for the Barents Sea. Maps of concentration, age and forms of the Arctic Ocean in vector SlGRlD-3 format with a sample name aari arc YYYYMMDD pl a.ZIP (which contains SHP, DBF, SHX, PRJ files) are taken into account as equivalent maps. Examined files downloaded from the website http //www.aari.ru/projects/-ecimo/index.php im=100. Scale of the map is 1 ... 

For security reasons in the Second World War, radar bands were designated by letters the custom was retained even after the need for security had disappeared. At present, this letter system is not uniform among manufacturers, but Table V gives the most widely used distribution. The frequencies universally employed are shown. 

Frequency Allocations. Under ideal conditions, an optimum frequency or frequency band should be selected for each appHcation of microwave power. Historically, however, development of the radio spectmm has been predominantly for communications and information processing purposes, eg, radar or radio location. Thus within each country and to some degree through international agreements, a complex Hst of frequency allocations and regulations on permitted radiated or conducted signals has been generated. Frequency allocations developed later on a much smaller scale for industrial, scientific, and medical (ISM) appHcations. 

Laser sources that emit in the mid-ir region of the spectmm (2—5 -lm) are useful for detection of trace gases because many molecules have strong absorption bands in that region. Other appHcations include remote sensing and laser radar. Semiconductor lead—salt (IV—VI) lasers that operate CW at a temperature of 200 K and emission wavelength of 4 p.m are commercially available however, they have relatively low output powers (<1 mW) (120). 

The electron paramagnetic resonance effect was discovered in 1944 by E. K. Zavoisky in Kazan, in the Tartar republic of the then-USSR, as an outcome of what we would nowadays call a purely curiosity-driven research program apparently not directly related to WW-II associated technological developments (Kochelaev and Yablokov 1995). However, a surplus of radar components following the end of the war did boost the development of EPR spectroscopy, in particular, after the X-band ( X meaning to be kept a secret from the enemy) was entered in Oxford, U.K., in 1947 (Bagguley and Griffith 1947). 

But, it is substantially better than the tens of kilohertz that classic amorphous silicon or OFETs can achieve. It is also in frequency ranges of interest for many mobile communication systems and radar detection bands and, therefore, would provide sufficient capability for a range of RF opportunities. 

Mark E. Davis and Braham Himed, L Band Wide Area Surveillance Radar Design Alternatives, Internationa], Radar 2003 — Australia, September 2003. 

Peter Zulch, Mark Davis, Larry Adzima, Robert Hancock, Sid Theis, The Earth Rotation Effect on a LEO L-Band GMTI SBR and Mitigation Strategies, IEEE Radar Conference, Philadelphia, PA, April 2004. 

An example of required radar peak power for different pulse/illumi-nation times, for X band radar equipped with a 30 dB antenna, is presented in Figure 1. For X band radar, emitting a 1 /is pulse, the peak... 

Figure 1. Transmitted power versus transmitted pulse length for X-band radar (30 dB antenna gain) — detection of ldBsm (1 square meter) target at distance 50 km.

R. M. Narayanan and M. Dawood, Doppler estimation using a coherent ultra wide-band random noise radar , IEEE Trans. Antennas Propagat., vol. 48, pp. 868-878, June 2000. 

D. Garmatyuk and R. M. Narayanan, Ultrawide-band noise synthetic radar Theory and experiment , in IEEE Antennas Propagat. Soc. Int. Symp. 1999, vol. 3, Orlando, FL, July 1999, pp. 1764-1767. 

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