GB1220952A - Microwave antenna arrays - Google Patents

Abstract

1,220,952. Aerials. TEXAS INSTRUMENTS Inc. 19 March, 1968 [3 April, 1967 (2)], No. 13199/68. Heading H4A. [Also in Divisions H1 and H2] A microwave aerial system having a plurality of R.F. modules each with front and rear end walls and an aerial spaced from the front end wall comprises for each module an electrical connector disposed at the rear end wall and a rear support assembly having an electrical connector mating with the first electrical connector; the modules are arranged in rows such that each two adjacent rows form opposite sides of a cooling fluid duct with the rear support assembly. The aerial system is part of a solid-state airborne radar as in Specification 1,124,266, each module including a transmitter and receiver, a frequency multiplier and phaseshifting means for electronic beam scanning. Since the usual radio frequency is some 9 Gc/s. and the aerial elements are spaced by #/2, adequate cooling is a difficult problem of which the invention is directed to a solution. In the embodiment each module 12, Figs. 6, 8, includes a centre plate 26 preferably integral with side walls 22, 24 to enhance heat transfer and chambers 28, 30 hermetically sealed by lids 32, 34; hermetically sealed coaxial connectors 42, 44 extend through and project from wall 16; connectors 46 extend through a ceramic block 48 hermetically sealed around each connector; and an indexing pin 50 is provided. Each module is plugged into a support structure 60, Fig. 12, with each adjacent pair of rows forming the opposite side walls of cooling fluid ducts 80a, 80b. The modules are secured in place by H-shaped clamping plates (82, Figs. 2 and 3, neither shown). Cooling, Fig. 12.-Cooling fluid header 88a supplies ambient air under pressure through inlet ports 90a, exhaust being through exhaust ports 92a and mutatis mutandis for header 88b ; the air flow described provides the same net cooling effect on all modules. Aerial details, Figs. 18, 19.-The aerial assembly consists of a sleeve 150, a conductor 152, a ceramic disc 154 and a pair of aerial elements 156, 158. Portions 152b, 152c are of diameters for impedance transformation and halves 150a, 150b of sleeve 150 afford a balun, slits 160 being approximately #/4 long. Element 158 is soldered to a slot 162, and the aerial is disposed #/4 from module wall 14 forming part of the ground plane. The assembly provides a hermetically sealed connection through the wall. Circuits in each module 14 are described in detail in Specification 1,203,952 and their layout in the module is described, Figs. 15 to 17 (none shown). For ease of maintenance, the circuit boards are mounted by a bracket system (170, Fig. 22a, not shown) formed from a thin nickel foil having straps (178) cut therefrom and bent upwards. A circuit (174) is placed over a base-plate (172), the straps are bent over metallized pads (177) on the surface of the circuit and then welded thereto (the weld can be broken to remove a faulty circuit without damaging a bracket). Springs (175), cut from the base-plate, ensure good thermal and electrical contact. In an alternative method of securing a circuit in position a gusset (181, Fig. 22b, not shown) may be welded to each strap. Electric couplings.-Two microwave strip transmission lines (202, 208, Fig. 23, not shown) are connected by a strap (131) of gold wire mesh which is welded thereto at various points (209); or a solid metal ribbon may be utilized. The width of the strap may be increased to eliminate impedance discontinuity. Feed-through connection between strip lines (226, 228, Fig. 24, not shown) on respective substrates (222, 224) is made by a wire (232) passing through a quartz sleeve (230) and spot welded to the lines; the characteristic impedance of the connection is adjustable by varying either the length of an insulating film on the sleeve (230) or the diameter of the wire.