Abstract: A target classification method for radar systems wherein, in particular, jet aircraft, are classified in that the blade repetition rate and, in a further step, the number of blades, of an engine rotor wheel are determined and thus the type of engine is identified. Helicopters are classified by determining the blade repetition period of the primary or tail rotor.

Abstract: In an aircraft on-board radar system employing a sharply focused directional pattern which is able to sweep over a given space range, the range in the MPRF mode is limited primarily by the ground clutter picked up via the side lobes of the antenna pattern. To increase the range, an antenna is employed which, due to asymmetrical distribution of the antenna aperture (signal field) in the elevational direction with respect to the center of the aperture, has a significantly higher side lobe spacing below the principal lobe than above the principal lobe. Because of the side lobe spacing being greater below the principal lobe, less ground clutter components are picked up while the smaller side lobe spacing above the principal lobe results in hardly any increase of clutter components in the echo signal.

Abstract: With a frequency-agile pulsed doppler radar with high pulse repetition frequency (HPRF) in the unambiguous velocity region, in order to measure the range of a target the complex time signal derived from the echo signals of a coherent processing interval (CPI) is transformed into the frequency domain, the transformed spectrum is multiplied by a bandpass function with a mean frequency coinciding with the doppler frequency of the target, and the product is transformed back into a time signal. The real envelope of this re-transformed time signal displays a definite leading edge and a steady state region, from which the echo travel time can be estimated. Particular advantages may be derived for the pulsed doppler radar set from a plurality of frequency agile transmitter/receivers operated at the same time at different frequencies, and whose frequency switching times are time-staggered.

Abstract: In an aircraft on-board radar arrangement including a search radar and a radar warning receiving system, an additional receiving branch is provided to which are fed foreign radar signals received by the sharply focused transmit/receive antenna of the search radar, with the output of the additional receiving branch being connected to the radar warning receiver. This results in a greater angular resolution and a considerable increase in range, which again leads to a more detailed and early detected of threatening situations. By using already available components and because of the simple configuration of the additional receiving branch, additional costs remain low.

Abstract: A radar arrangement which is particularly useful for the terrain following radar of an aircraft avoids disturbances from rain echoes by utilizing an antenna arrangement with a transmitting/receving directional antenna which is circularly polarized. A supplementary receiving antenna of orthogonally-circularly polarized type is used in conjunction with the directional antenna. From a comparison of the signal level distinctions is made between a target and a rain echo. The rain echo can thus be suppressed to give a truer target signal.

Abstract: In a radar system comprising equipment for transmitting frequency modulated pulses and compressing the received signals in a filter for frequency-dependent weighting, the weighting is asymmetrical in a manner such that the leading sidelobes of the pulse compression signal are reduced and the lagging sidelobes are raised. The reduced leading sidelobes can easily be reduced below an amplitude threshold so that the main echo lobe within the pulse compression signal is reliably acquired for determining the closest target distance. The invention may advantageously be applied to ground tracking radars.

Abstract: For an aircraft radar arrangement, particularly helicopters, a first frequency is provided at a maximum of atmospheric attenuation and a second frequency near the first frequency in a region of less atmospheric attenuation, preferably at 60 GHz and 50 GHz. The first frequency serves to provide obstacle warnings, the second to provide for moving target detection and navigation. The mm wave components of the arrangement can substantially be used for both frequencies so that significant savings in weight, space and costs result.

Abstract: In a remote-control system for guiding a missile from an aircraft which is equipped with jamming transmitters, a radar, and a predictor, radio communication to the missile is established to transmit trajectory instructions through the jamming transmitter equipment. For this purpose, after launching the missile, the jamming transmitter is tuned in a narrow band to the frequency of the radio communication, while interrupting the jamming transmission if necessary, and modulated with the instructions to be transmitted.