ANALSIS OF CROSS SECTION IN RADAR DETECTION

Radarski sistemi so namenjeni odkrivanju ciljev v zraku, na morju ali na kopnem. Najpomembnejši parameter, ki vpliva na radarsko zaznavanje posameznih ciljev, je povprečna odmevna radarska površina. Nastopa v radarski enačbi, ki na splošen in enostaven način opisuje princip radarskega zaznavanja. Z analizo povprečne odmevne radarske površine smo prikazali pomembnost tega parametra pri radarskem zaznavanju. V nalogi je opisan princip radarskega zaznavanja in definicija povprečne odmevne radarske površine v okviru radarskega zaznavanja ciljev s posameznimi radarskimi sistemi. Bistven del naloge zajema analizo in opis posameznih metod za zmanjševanje povprečne odmevne radarske površine, ki so se razvile predvsem za vojaške potrebe. Ena izmed metod je površinsko oblikovanje, kjer lahko s primernimi oblikami posameznih objektov preusmerjamo vpadne elektromagnetne valove stran od radarskih sprejemnikov in s tem dosežemo želeno nevidnost. Podrobno smo analizirali površinsko oblikovanje, ki predstavlja najpomembnejšo metodo za zmanjševanje povprečne odmevne radarske površine. Za preprosta telesa smo z matematičnimi izračuni prikazali vpliv površinskega oblikovanja teles na vrednost njihove povprečne odmevne površine. Na specifičnih modelih osnovnih oblik smo s pomočjo analitičnih izračunov v MatLab-u in simulacij v COMSOL simulatorju analizirali vpliv različnih 2-dimenzionalnih oblik. Pomemben način zmanjševanja povprečne odmevne radarske površine je tudi uporaba posebnih radarskih absorpcijskih materialov. Analizirali smo lastnosti teh materialov, vpliv njihove uporabe in s pomočjo simulacij je bila na posameznih primerih prikazana in potrjena njihova učinkovitost. Rezultate simulacij smo tudi primerjali in potrdili z analitičnimi izračuni. Vse metode zmanjševanja povprečne odmevne radarske površine lahko združimo v skupno tehnologijo, ki se imenuje stealth tehnologija. Razvoj te tehnologije je namenjen vojaški obrambi in temelji na skrivanju pred nasprotnikom oz. pred radarskimi sistemi. Po drugi strani pa so se razvile tudi uspešne metode in tehnologije, ki lahko uspešno kljubujejo stealth tehnologiji.Radar systems are designed to detect targets in the air, at sea or on land. Radar cross section is the most important parameter that affects the radar detection of the individual targets. It is a part of radar equation, which in general and simple manner describes the principle of radar detection. By analyzing the radar cross section it has been demonstrated the importance of this parameter in radar detection. In this thesis, the radar detection principle and radar cross section definition are described in aspect of target detection with individual radar systems. The main part of this paper includes the analysis and description of various methods for reducing the radar cross section. These specific methods have been developed primarily for military needs. One specific method is surface shaping where you can by creating adequate shapes of individual objects redirect incident electromagnetic waves away from radar receivers and thereby achieve the desired invisibility. The surface shaping has been analyzed in details. Surface shaping is the most important method for reducing radar cross section. Mathematical calculations show the effect of surface shaping to radar cross section values for simple objects. The impact of surface shaping has been analyzed on specific models of basic shapes using analytical calculations in MatLab and simulations in COMSOL simulator for different two-dimensional shapes. An important way of reducing radar cross section is also the use of special radar absorbing materials. The characteristics and features of these materials have been analyzed. Their effectiveness have been confirmed with help of simulations. The simulation results were also compared and validated with analytical calculations. All methods of reducing radar cross section can be joined in a common technology called stealth technology. The development of this technology is primary intended for military defense and it is based on hiding against the enemy or from radar systems. On the other hand there have been also developed some successful methods and technologies that can effectively resist the stealth technology