Where reflection coefficient k of the surface of the sea is in a relatively wide range and as the ratio of the antenna height to the wavelength is larger, a radar system can eliminate ambiguities in measuring a target height of a low elevation angle on the sea surface. An antenna receives two beams, one beam having slightly different elevation angle from the other. An antenna direction adjusting mechanism adjusts, on the basis of tan.sup.-1 (ha/R), a direction in which receiving sensitivity of o...

A radar reflector (4, 5) comprises a hollow, generally spherical or conical radar transmitting housing (6) containing a radar reflecting assembly (10) having a number of trihedral cube corner reflecting elements arranged in strings one above the other and with a number of the strings arranged side-by-side around the inside of the housing (6). The radar reflecting assembly (10) may comprise strings of reflecting elements with the origins of all of the reflecting elements lying on and being arrang...

A circuit for generating an output signal L indicative of the mean clutter level at a selected location in the field of view of a radar apparatus, particularly the sea surface which exhibits a swell pattern. The circuit includes processing circuits which generate weighting coefficients (a.sub.1, a.sub.2, . . . a.sub.N) used to weight the amplitudes of returns derived respectively from a group of N discrete locations which precede in range and or succeed in range the selected location. The circui...

Improved radar apparatus includes a rotatable antenna structure which includes an antenna disposed within a housing which is rotatably driven. Also disposed within the rotatable housing are a unitary magnetron, microwave circulator and microwave limiter device which rotates when the housing is rotatably driven. Additionally, a transmitter, such as a modulator coupled to the unitary device and a receiver also coupled to the unitary device are disposed within the rotatable housing. Preferably, the...

A radar system comprises an antenna including a reflector having two vertically mounted receiving elements and two receiving channels connected to the elements. The receiving elements form, in cooperation with the reflector, almost coinciding cosecant-square beamed patterns. A measuring circuit connected to the two receiving channels measures the phase difference between the signals received by the receiving elements. A transformation unit connected to the phase measuring circuit converts the ph...

A continuous wave pseudonoise radar system which employs a large word rate to avoid spillover and other noise. Spillover is the electromagnetic energy that is transmitted from the transmitting antenna directly to the receiving antenna. In other words, the spillover is not reflected from the target. The word frequency is thus made higher than the highest expected doppler. The high word rate would normally cause an ambiguous range indication because the word wavelength would be less than twice the...

In order to provide coverage of a full 360 degrees of azimuth even when heeled a radar reflector consists of ten trihedral reflectors directed outwardly of a major axis the inner eight of which are formed in vertically displaced pairs of dihedral reflectors sub-divided by a divider portion which reflectors are positioned such that the apexes of the two central dihedral reflectors are relatively displaced about the major axis by an angle a and the apexes of the dihedral reflectors on each side of...

An interrogator/transponder for identification of co-operating pulse radar-fitted marine vessels comprises a detector responsive to signals in the radar frequency band and a C-band transmitter/receiver connected such that on receiving a C-band interrogating signal together with a radar signal an identity signal produced by a signal generator is transmitted. When used for interrogation an interrogating signal is produced by a second signal generator for transmission with the radar signal and the ...

A target tracking airborne active radar system in which a reduction in transmitter power is achieved by using individual amplifiers in the aerial quadrant channels. The amplifiers provide gain on transmission and negligible loss on reception and are realized by Impatt diode/hybrid junction modules.

A radar system for continuously displaying target returns on a conventional television receiver. The radar includes a console connected to a rotating scanner unit through conventional slip rings. The scanner unit contains a radar antenna coupled to a receiver and transmitter, and a power supply generating a multitude of high-voltage and circuit supply voltages from AC power. A position transducer measures the rotary position of the scanner unit and triggers the transmitter as the scanner unit ro...