Communications: directive radio wave systems and devices (e.g. – Directive – Utilizing correlation techniques
Patent
1996-12-16
2000-08-08
Issing, Gregory C.
Communications: directive radio wave systems and devices (e.g.,
Directive
Utilizing correlation techniques
342380, G01S 316
Patent
active
061008443
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a radar apparatus having a sidelobe blanking circuit, provided with a main channel comprising a directive antenna, having a main lobe and sidelobes, and a main receiver; an auxiliary channel comprising an auxiliary antenna, having a directivity substantially lower than the directivity of the directive antenna, and an auxiliary receiver; and comparison and switch means connected to the main receiver and the auxiliary receiver for passing signals for further processing when the signals appear stronger in the main channel than in the auxiliary channel.
A radar apparatus of this kind is known from the patent DE 30 28 225 C1. The known radar apparatus is based on the principle that the auxiliary antenna gain is greater than the directive antenna sidelobe gain. Sidelobe suppression is then obtained to a satisfactory extent, except for noise sources entering the directive antenna main lobe flanks. Particularly, if the radar apparatus is provided with a difference channel for determining the error angle between a direction of the main lobe and a direction of a target, a noise source entering this way constitutes a considerable drawback.
SUMMARY OF THE INVENTION
The present invention largely obviates this problem by actively involving the difference channel in the sidelobe blanking (SLB) process. It is thereto characterised in that the radar apparatus is provided with a difference channel comprising a difference antenna, for determining an error angle between a direction of the main lobe and a direction of a target, and a difference receiver; and in that the comparison and switch means are designed for passing signals for further processing when the signals appear stronger in the main channel than in the auxiliary channel and the difference channel in combination.
From U.S. Pat. No. 3,916,408 a radar apparatus provided with a coherent sidelobe canceller is known having an auxiliary antenna with a null in the direction of the main lobe of the directive antenna. This nul prevents clutter returns from entering the auxiliary channel, which clutter returns tend to degrade the coherent sidelobe cancelling.
A favourable embodiment of the invention is characterised in that the comparison and switch means are designed for passing signals for further processing when the signals appear stronger in the main channel than in the auxiliary channel and in the difference channel.
A further favourable embodiment of the invention is characterised in that a combined channel is provided, comprising a summation network for summing output signals of the auxiliary antenna and of the difference antenna, a combined receiver, connected to the output of the summation network; and in that the comparison and switch means are designed for passing signals for further processing when the signals appear stronger in the main channel than in the combined channel.
In this embodiment, the combined channel incorporates, practically unchanged, all characteristics of the difference channel. Thus, the combined channel may be used for the determination of error angles; the only difference being that the sidelobes are raised as it were by combining them with the output signals of the auxiliary antenna. The aim is then to allow the antenna gain of the combined antenna to be greater than that of the directive antenna, except in the central part of the main lobe.
A still further favourable embodiment of the invention is obtained for a radar apparatus equipped with an array of antenna elements from which the directive antenna is derived for the main channel by means of a main summation network. This embodiment is characterised in that for a combined channel, a combined auxiliary antenna and difference antenna is derived from the array by means of a collective summation network, that a combined receiver is provided, connected to the collective summation network, and that the comparison and switch means are designed for passing signals for further processing when the signals appear str
REFERENCES:
patent: 3778829 (1973-12-01), Longuemare, Jr. et al.
patent: 3875569 (1975-04-01), Hill et al.
patent: 3900874 (1975-08-01), Larkin et al.
patent: 3916325 (1975-10-01), Lund
patent: 3916408 (1975-10-01), Evans et al.
patent: 3943511 (1976-03-01), Evans et al.
patent: 4021805 (1977-05-01), Effinger et al.
patent: 4525716 (1985-06-01), Carlin
patent: 4931977 (1990-06-01), Klemes
patent: 5045858 (1991-09-01), Eberhardt et al.
patent: 5302961 (1994-04-01), Murrow et al.
patent: 5361074 (1994-11-01), Hansen
patent: 5539407 (1996-07-01), Scholz
Skolnik, Merrill, "Introduction to Radar Systems", 2nd Edition, pp334-335, 1980.
Wardrop, Brian, "Digital Beamforming and Adaptive Techniques" IEEE Tutorial Meeting on Phased Array Radar, 1989.
Kleijer Hugo
Scholz John Arthur
Whiting Ian Gerald
Hollandse Signaalapparaten B.V.
Issing Gregory C.
LandOfFree
Radar apparatus with sidelobe blanking circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Radar apparatus with sidelobe blanking circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radar apparatus with sidelobe blanking circuit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1154617