US2683011A

US2683011A - Collapsible antenna support for aircraft microwave landing systems

Info

Publication number: US2683011A
Application number: US210738A
Authority: US
Inventors: Francis L Haggerty
Original assignee: US Air Force
Current assignee: US Air Force
Priority date: 1951-02-13
Filing date: 1951-02-13
Publication date: 1954-07-06
Anticipated expiration: 1971-07-06

Description

y 1954 F. L. HAGGERTY 2,683,011

COLLAPSIBLE ANTENNA SUPPORT FOR AIRCRAFT MICROWAVE LANDING SYSTEMS Filed Feb. 15, 1951 2 Sheets-Sheet l INVENTOR. FEBNC'AS L, H66 EE 7') July 6, 1954 F. 1.. HAGGERTY COLLAPSIBLE ANTENNA SUPPORT FOR AIRCRAFT MICROWAVE LANDING SYSTEMS 2 Sheets-Sheet 2 Filed Feb. 13 1951 nTTo h/EY FIZE/VF W m N 4 M 14 g M L m .0 Mw mw n fln/ W w 3 E E V 5 Z w ofi MM 8 0/ :0 er mm Km 5 Patented July 6, 1954 UNITED STATES PATENT OFFICE COLLAPSIBLE ANTENNA SUPPORT FOR AIR- CRAFT MICROWAVE LANDING SYSTEMS Francis L. Haggerty, St. James, N. Y., assignor to the United States of America as represented. by the Secretary of the Air Force Application February 13, 1951, Serial No. 210,738

. 6 Claims. 1

The present invention relates to a collapsible antenna support for use in an aircraft microwave landing system.

The primary object of the invention is to provide a supporting structure for a microwave antenna or radiator in which a simple framework includes at least one frangible joint adapted to fracture in case the antenna or framework is struck by an aircraft, whereby the framework immediately collapses to avoid interrupting continued movement of the aircraft.

A further object of the invention is to provide an antenna supporting structure comprising a framework in which several elongated frame members are pinned or bolted together in such a manner that shearing or fracture of a joint will allow the whole framework to collapse by a pivoting movement about other joints not susceptible to fracture.

Another object of the invention is to provide an antenna supporting structure for a microwave antenna particularly intended for location near one end of an aircraft runway and to provide such a supporting structure including a pair of side frames of triangular form made by connecting three bars at their ends by bolts and to provide at the upper apex thereof a frangible bolt adapted to fracture in case the antenna or supporting structure is struck by an aircraft, so that the triangular end frames will collapse without further interrupting movement of the aircraft and without causing serious damage to the aircraft. I

Another object of the invention is to provide an antenna supporting structure for a microwave antenna particularly intended for use in an aircraft microwave landing system and to include in the supporting structure means for quickly and easily varying the angular disposition of the antenna with respect to the plane of the aircraft landing strip;

Another object of the invention is to generally improve the antenna supporting structure for the directive antenna as disclosed in the patent to G. B. Litchford et al. No. 2,513,338, granted on July 4, 1950. I

The above and other objects of the invention will become apparent upon reading the following detailed description in conjunction with the accompanying drawings, in which:

Fig. 1 is a side elevation view of the present antenna supporting structure.

Fig. 2 is a rear elevation view of the present antenna supporting structure but with the wave modulator and wave guide removed.

Fig. 3 is a plan view of the aircraft runway and associated microwave landing system.

In the patent to Litchford et a1. referred to refinements in the supporting framework for the antenna. The radiator should include the concave reflector and pair of cylindrical parabolas secured thereto as shown in the patent to Litchford et al., although in the present description only the reflector will be referred to.

Fora description of the invention, reference is made to Figs. 1 and 2 wherein there is shown a concrete slab or sub-base l, the upper surface of which is preferably flush with the ground or even a little below ground level. Mounted thereon in any suitable manner is a pair of similar and parallel timbers 2 and 3 which support another pair of timbers 4 and 5 bridging the space between the foundation timbers 2 and 3. Laid along the upper surfaces of the base timbers 4 and 5 are horizontal angle irons 6 and i about the same length as the timbers 4 and 5. Fixed to the remote vertical sides of these timbers are short upright angle irons 8 and 9 joined by a transverse angle iron Ill bolted at opposite ends to flanges of the members 8 and 9 and bearing on the upper edges of the angle irons 8 and l. Inwardly extending adjusting screws II extend through the members 8 and 9 and bear on the upright flanges of angle irons 6 and l to provide for limited crosswise adjustment of the antenna supporting framework after the installation has been completed. The base members 6 and I may be fastened down to the timbers 4 and 5 respectively after the structure is completed and properly adjusted, such fastening being accomplished by lag screws passing through the horizontal flanges of angle irons 6 and 1. At the forward ends of

members

6 and 7 there are similar uprights l2 and I3 pivotally mounted thereon by bolts l4. Similar bolts 15 serve to pivotally mount sloping members It and ii, connected to uprights I 2 and I3 by light duty shearable bolts [8. and l! are angle irons of a type similar to the base members 6 and 1. The upright members I2 and I3 are joined by the transverse cross plate l9 having end flanges 20 and 2! extending forwardly, as seen in Fig. l. Noting Fig. 2 of the drawings, the transverse plate 19 extends outwardly of the members [2 and is to form side projections therefrom. Another rigidifying bar or plate 22 connects the members [2 and 13, as

The frame members l2, I3, {6'

by welding, and there is a diamond-shaped frame of light bars 23 to 2B welded to the members [2, l3, l9 and 22, as shown in Fig. 2. Welded to the sloping members 12 and [3 in bridging relation is a bar or plate 21.

Supporting elements are provided near the lower end of sloping members 16 and I! to mount a wave modulator 28 receiving microwave energy by way of wave guide 29. The modulated energy is conducted from the modulator 2B to the reflector 30 by way of wave guide 3|. One or more separable joints are provided in the wave guide 3|, as at 32. Extending upwardly in a sloping manner from the lower ends of members i8 and H are

angle irons

33 and 34 joined at their upper ends by a bar or plate 35. A pair of transverse angle irons 36 and 31 welded to the members It, I! and 33, 34 serve to carry a base 38 secured to the modulator 28. The adjacent members It and 33 and I1 and 34 are connected by bars 39 which are also welded to angle irons 35 and 31.

Each of the uprights l2 and 13 carries an elongated angle bracket 40 bolted to the associated uprights with wood strips 4| therebetween. E'ach bracket is provided with a slot 42 to slidably receive a pin 43 carried at the lower end of a long channel iron 44, the web of which is at the forward side to provide a mounting surface for antenna supporting frame 45. Below the upper end of each channel iron 44 a pivot 45 serves to mount a link 4']. The upper end of each link 41 is mounted on a transverse shaft 48 and keyed thereto. The opposite ends of the shaft are journaled in friction-type bearing members as bolted on the remote faces of flanges 29 and ill (see Fig. 2). Thus the similar links 'll rotate together and tend to stay in any adjusted position by reason of the frictional drag of the bearing assemblies 49. Adjustment of the links and consequent adjustment of the angular setting of the reflector 30 is effected by means of screws 59 threaded through the webs of channel irons 44 and bearing on the links below the shaft 48. As may be seen in Fig. l the rim of reflector 30 is slightly off the true vertical but by adjusting the screws 50 toward the links 4'5 the angularity of the reflector 30 with respect to vertical may be reduced.

The antenna supporting frame 45 comprises a ring section 51 having various rods 52 to SI welded thereto and to a hoop 62 secured to the reflector 30 by brackets 63. Adjustably mounted atop the hoop 62 is a theodolite 64 for accurately lining the antenna up with respect to the landing strip or runway. As may be seen in Fig. 3, the microwave radiator is set up on the longitudinal axis of the runway at a distance from one end of the runway. The wave guide 2% extends laterally from the runway axis to a microwave station, set perhaps two hundred feet off the axis.

For a consideration of the mode of operation of the invention it may be assumed that an aircraft is making a landing in the direction of arrow A (Fig. 3) on the runway. Should the brakes fail or for some other reason the aircraft rolls off the runway directly toward the microwave radiator, the undercarriage or possibly the nose of the aircraft will strike the radiator. In usual practice the top of the reflector 3!! is about six feet above the ground level. This sudden blow will stress the whole radiator structure but the weakest part is the shearable bolts 18 at the apex of the supporting framework. Therefore these bolts will fracture. and the uprights I2 and it will pivot rearwardly about bolts I i at their lower ends. As the uprights rotate rearwardly and downwardly, the opposite extending ends of the plate l9 serve as abutment members and will contact the forward edges of brace members it and ll which are in pivotal path of the abutment members and thus cause these members to also rotate rearwardly. The forward supporting members or uprights act to push the other s1 porting members, including the attached modulator, rearwardly and finally downwardly so that the whole structure folds up or collapses. As can be seen in Fig. 1, the

base angle irons

6 and 7 jut out beyond the ends of the base timbers 4 and 5 at the rearward ends, so that the interconnected members l6, ll and 33, 3d free to drop down to the ground level. Of course the collapsing of the supporting structure causes various joints in the wave guide to come apart and other damage, such as possible bending of the reflector 30, but the important factor is the damage caused to the aircraft itself. With the invention here disclosed the supporting structure and elements carried thereby are adapted to collapse onto the ground and thus present much less of an obstruction to the aircraft so that the craft can roll on over the complete microwave radiator with a minimum of damage thereto. Practice has shown that the collapsible an ha support has functioned very well and has prevented serious damage to large aircraft on more than one occasion.

While it is true that overrunning the runway on landing is the most likely occurrence whereby the antenna will be struck, it has been found that aircraft coming in for a landing in a direction opposite to that of arrow A may also strike the antenna structure. In this case the initial force may be applied to the sloping brace men bers I6 and I! but after fracture of the small shear bolts or pins I8, the members it and H will contact the ends of plate 19 and thus push the upright forward portions of the antenna structure forwardly. When the antenna is struck by an aircraft which is still airborne the collapsing of the structure will enable the aircraft to clear the obstruction very nicely, even though the initial impact may possibly damage a tire of the aircraft undercarriage.

The relative size and strength of the antenna parts and supporting structure may be varied within wide limits but the suggested size of the angle irons is two or three inches across the flanges. The shearable bolts It; may be of mild steel, aluminum or brass and should not be greater than three-eighths of an inch in thickness. If a mild steel bolt is chosen the size suggested is one-quarter inch. Until the antenna is struck by an aircraft the only important stresses thereon are those due to winds, so the relative strength of the supporting structure should be designed with wind velocities of a particular location in mind. The adjustment of the reflector by the use of the adjusting screws 5c is another important feature but one which seems to require no further elaboration.

The embodiments of the invention herein shown and described are to be regarded as illustrative only and it is to be understood that the invention is susceptible of variations, modifications and changes within the scope of the appended claims.

I claim:

1. An antenna supporting structure for a microwave radiator comprising, a pair of elongated spaced apart parallel base members,

a pair of upright antenna supporting mem bers pivotally mounted at one end of said base members, transverse members rigidly connecting said pair of upright members, a pair of brace members pivotally mounted at the other end of said base members and extending to the upper ends of said upright members, shearable bolts serving to connect the intersecting upper ends of said upright members and said brace members, an antenna mounting ring secured to said upright members and substantially parallel thereto, struts rigidly connected to said ring and extending away from said upright members, and a hoop rigidly connected to said struts and adapted to receive the convex side of a parabolic microwave reflector.

2. An antenna supporting structure for a microwave radiator comprising, a pair of elongated spaced apart base members, a pair of upright antenna supporting members pivotally mounted at one end of said base members, a transverse member rigidly connecting said pair of upright members close tothe upper ends thereof, means to brace said upright members and retain them in a predetermined upright position, separate bearing means mounted on opposite ends of said transverse member, a shaft extending through said separate bearing means, a pair of links keyed to said shaft and extending downwardly in the same plane, an upright channel member pivotally mounted on the lower end of each link, means providing a sliding connec tion between the lower end of each channel member and a corresponding one of said upright members, means to adjust the angular relation between said pair of links and the corresponding channel members, and means formounting a parabolic microwave reflector on said channel members.

3. An antenna supporting structure for a microwave radiator comprising, a pair of elongated spaced apart base members, a pair of upright antenna supporting members pivotally mounted at oneend of said base members, a transverse member rigidly connecting said pair of upright members close to the upper ends thereof, a pair of brace members pivotally mounted at the other end of said base members and extending to the upper ends of said upright members, shearable bolts serving to connect the intersecting upper ends of said upright members and said brace members, separate bearing means mounted on opposite ends of said transverse member, a shaft extending through said separate bearing means, a pair of links keyed to said shaft and extending downwardly in the same plane, an upright channel member pivotally mounted on the lower end of each link, means providing a sliding connection between the lower end of each channel member and a corresponding one of said upright members, means to adjust the angular relation between said pair of links and the corresponding channel members, and means for mounting a. parabolic microwave reflector on said channel members.

4. An antenna supporting structure for a microwave radiator comprising, a pair of elongated spaced apart base members, a pair of substantially vertical antenna supporting members pivotally mounted at one end of said base members, transverse members rigidly connecting said pair of substantially vertical members, abutment means extending from the respective sides of said supporting members in substantially transverse alignment, a pair of brace members pivotally mounted at the other end of said base members and extending to the upper ends of said substantially vertical members in the pivotal path of the abutment means, and shearable bolts serving to connect the intersecting upper ends 'of said substantially vertical members and said brace members,'whereby on shearing of the bolts the supporting members pivot, the abutment means pivoting therewith, engaging the brace members to collapse the supporting structure.

5. An antenna supporting structure for a microwave radiator comprising a pair of elongated spaced apart base members, a pair of upright antenna supporting members pivotally mounted at one end of said base members, a transverse member rigidly connecting said pair of upright members .adjacent the upper ends 7 thereof, the ends of said transverse member projecting outwardly from the sides of said upright members, a pair of brace members pivotally mounted at the other end of said base member and extending to the upper ends of said upright members, shearable bolts serving to connect the intersecting upper ends of said upright members and said brace members, said outward projections of said transverse member serving as abutment means extending into the planes of the respective brace members whereby on shearing of said shearable bolts, the upright members will pivot, the projections of the transverse member engaging the brace members in the pivotal path thereof to pivot the brace members causing collapse of the supporting structure.

6. An antenna supporting structure for a microwave radiator comprising, means providing a ground supported base, a pair of spaced apart upright antenna supporting members pivotally mounted at their lower ends on said means, a transverse member rigidly connecting said pair of upright members'adjacent the upper ends thereof and extending outwardly therefrom, a pair of inclined brace members pivotally mounted at their lower ends on said means and extending upwardly to the upper ends of said upright members, said outward extensions extendingrespectively into the planes of the respective brace members, shearable pin means serving to connect the intersecting upper ends of said upright members and said brace members whereby on shearing of said pin means the supporting members pivot on the base means, the said outward extensions of its transverse connecting member serving as abutment elements for engagement of the brace members and pivoting of the brace members rearwardly to collapse the supporting structure.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 123,122 Palmenberg Jan. 30, 1872 715,530 Wallace Dec. 9, 1902 721,307 Jasinski Feb. 24, 1903 1,188,610 Berger June 27, 1916 1,857,391 Nicholls May 10, 1932 2,083,054 Cline June 8, 1937 2,440,814 Van Wormer May 4, .1948 2,479,897 Baxter Aug. 23, 1949 2,500,952 Larson Mar. 21, 1950 2,572,430 Balton Oct. 23, 1951 2,577,233 Cullen Dec. 4, 1951