Radar mounted on helicopter

• US 3,896,446 A
• Filed: 07/13/1972
• Issued: 07/22/1975
• Est. Priority Date: 07/13/1972
• Status: Expired due to Term

• Current Assignee: Koki Nakatsuka, Teruo Kondoh
• Original Assignee: Koki Nakatsuka, Teruo Kondoh
• Inventors: Kondoh, Teruo, Nakatsuka, Koki
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US05/271,526
• Time in Patent Office: 1,104 Days
• Field of Search: 342/705,708,872
• US Class Current: 343/705
• CPC Class Codes: H01Q 1/27 Adaptation for use in or on movable bodies H01Q1/08, H01Q1/12, H01Q1/18 take precedence
• CPC Class Codes: H01Q 1/28 Adaptation for use in or on aircraft, missiles, satellites, or balloons
• CPC Class Codes: H01Q 25/005 providing two patterns of opposite direction; back to back antennas H01Q25/004 takes precedence
• CPC Class Codes: H01Q 3/04 for varying one co-ordinate of the orientation

Abstract

A radar antenna is fixedly disposed within a radar dome secured to a helicopter on the rotor head so as to have a maximum directive gain between selected adjacent two of blades radially extending at predetermined equal angular intervals from the rotor head. The antenna is electrically connected to a transmitter/receiver unit through a transmission line extending through a rotor shaft and a rotary joint disposed at the lower end of the shaft. In order to provide a dual antenna system or to form a combined primary and secondary radar, another antenna may be similarly provided on the helicopter but its maximum directive gain is directed between another selected pair of adjacent blades.

Claims

1. A radar apparatus for use with a helicopter having rotor means including a rotary shaft, a rotor head disposed upon the upper end of said rotary shaft, and a plurality of rotor blades radially extending at predetermined substantially equal angular intervals from said rotor head and defining a plane of rotation, said apparatus comprising an antenna system secured on said rotor head above the level of the rotor blades and disposed to have a direction of maximum gain between a selected pair of said adjacent rotor blades and substantially within the plane of rotation, said antenna system being rotatable with said rotor means, an oblate spheroidal radar dome, means mounting said radar dome with said antenna system disposed therein on said rotor head, a transmitter/receiver unit coupled to said antenna system to supply a transmission power to the latter and receive radar signals picked up by said antenna system, means coaxial with said rotary shaft connecting said antenna and said transmitter/receiver, and a rotary joint disposed at the rotor head to connect said antenna system to the lastmentioned means.

2. A radar apparatus as claimed in claim 1 further comprising a second antenna system disposed within said radar dome so as to have a direction of maximum gain between different pairs of adjacent rotor blades respectively and substantially within the plane of rotation, a pair of transmitter/receiver units comprising the first-mentioned transmitter/receiver coupled to the first-mentioned and second antenna systems respectively and each having means supplying transmission power to the associated transmitter/receiver unit and means to receive radar signals picked up by the associated antenna system, said first rotary joint and a second rotary joint disposed at the lower end of said rotor shaft to electrically couple said first-mentioned and said second transmitter/receiver units to the associated antenna systems respectively, said means coaxial with said rotor shaft comprising a pair of first and second transmission lines extending through the interior of said rotor shaft to couple said first-mentioned and said second rotary joints to the associated antenna system respectively, angle detector means coupled to said rotor shaft to generate signals for angular information corresponding to the maximum directive gain of said fiRst-mentioned and second antenna systems respectively and display means for receiving both the radar signals from each of said transmitter/receiver units and the signals for angular information from said angle detector means to display a position of a target.

3. A radar apparatus as claimed in claim 1, wherein said radar dome includes a strut rotatable with said rotor shaft and wherein said strut has secured thereto said antenna system and includes a counter weight to balance said antenna system.

4. A radar apparatus for use with a helicopter having rotor means including a rotor shaft, a rotor head disposed upon the upper end of said rotor shaft, and a plurality of rotor blades radially extending at predetermined substantially equal angular intervals from said rotor head and defining a plane of rotation, said radar apparatus comprising a pair of first and second antenna systems secured upon said rotor head so as to be rotatable with said rotor shaft, said first and said second antenna systems each having a direction of maximum gain and each being disposed having the respective directions of maximum gain between different pairs of said adjacent rotor blades and disposed subtantially within the plane of rotation, an oblate spheroidal radar dome, means mounting said radar dome on said rotor head with said antenna systems disposed therein, a pair of transmitter/receiver units, rotary joint means at the lower end of said rotary shaft to electrically couple said antenna systems to said transmitter/receiver units, transmission line means extending through the interior of said rotary shaft to electrically connect said antenna systems to said transmitter/receiver units, angle detector means coupled to said rotary shaft to generate a signal for angular information corresponding to the maximum directive gains of said antenna systems, and display means for receiving both radar signals from said antenna systems and said signal for angular information from said angular detector means to display a position of a target.

5. A radar apparatus as claimed in claim 4 wherein said rotary joint means comprises a first rotary joint comprising an angular waveguide rotary joint and a second rotary joint centrally disposed therein.

6. A radar apparatus as claimed in claim 5 wherein said transmitter/receiver units comprises a first transmitter/receiver unit for transmitting a signal within the Ku band of frequencies to perform the function of a primary radar and a second transmitter/receiver unit for transmitting a signal within the L band of frequency to perform the function of a secondary radar.