Abstract: The pass band filter has planar ring resonators arranged in pairs partly side-by-side and partly one above the other and a housing cover for each resonator. Each resonator includes a respective substrate provided with upper and lower conductive layers of high temperature superconductor material on respective opposite sides of the corresponding substrate, so that each planar ring resonator is operable in an edge-current-free TM010-oscillator mode. A respective coupling hole of radius r.sub.i is provided in the lower conductive layer (3) of each resonator and the lower conductive layers of both resonators in each pair face each other so that both resonators are coupled. Each housing cover has a respective truncated cone-shaped step ring (20) having a corresponding inner housing cover radius (r.sub.G). The radius ratio r.sub.i /r.sub.a (r.sub.

Abstract: A radar antenna arrangement (1) for a determination of the effective radar backscatter cross section .sigma..sub.eff of radar targets (2) as a function of the geometrical position of the target with reference to the radar antenna arrangement to be able to determine the effective radar backscatter cross section in a simple manner, even for a case where the radar beam no longer fully illuminates the radar target (2) to be examined and the position of the phase center (15) of the antenna (11) changes relative to the target (2), the radar antenna (11) is arranged on a rotatable antenna platform (10) outside of the rotation axis (12) of the antenna platform (10). In order to be able to scan the entire radar target (2) successively in time, the antenna platform (10) is pivotal about two axes (13, 14) that are perpendicular to the rotation axis (12). The radar target (2) to be examined is disposed on a revolving platform (3) which likewise rotates during the measuring process.