Abstract: The invention relates to a system for identifying targets as a friend or foe, which is operated in the millimeter-wavelength range by means of an interrogator and a transponder, with the interrogator and the transponder having essentially the same electronic assemblies and operating in essentially the same middle transmitting and receiving frequency, and with a large frequency difference between the two being tolerable. The interrogator operates with a directional transmitting/receiving antenna, whereas the transponder possesses an omnidirectional transmitting/receiving antenna.

Abstract: A phased-array antenna, particularly for the radar frequency range, comprising at least a predetermined number of transmit/receive radiator elements arranged linearly and/or matrix-shaped, a power distribution as well as a phase shifter network and a transmit/receive change-over arrangement. The transmit/receive change-over arrangement includes a serial feed comprising a waveguide with coupling in/coupling out locations disposed along its length and to which the phase shifter network, and possibly a further power distribution network, is coupled and also the transmitting/receiving arrangements are coupled. With this arrangement, an otherwise needed transmit/receive switch, for example, a circulator, is not necessary.

Abstract: Monitoring an area with the aid of a frequency-modulated continuous-wave radar includes emitting a frequency-modulated continuous-wave transmitting signal with at least one transmitting antenna having a directional pattern whose main azimuthal direction depends on the frequency of the transmitting signal. Related to a predeterminable direction, an azimuthal region is selected, and in the selected region, an azimuthal swivelling of the directional pattern of the transmitting antenna is carried out by changing the frequency of the transmitting signal. Also in the selected region, each azimuthal value is assigned a frequency value of the transmitting signal. The selected region is divided into a predeterminable number of azimuthal increments adjoining one another, and in each of the increments, a monotonous change of the frequency of the transmitting signal occurs.