Survivable Telescoping Antenna

Abstract

A survivable telescoping antenna having an outer housing and a plurality of elements nested therein. A radiator is mounted on the innermost element. When the elements are in a retracted position within the outer casing, the radiator is protected from severe environmental conditions by a closure element. Upon activation of a power source, the elements are erected from the outer casing causing ejection of the closure element and exposing the radiator for operation thereof. This antenna is thereby capable of surviving extreme environmental conditions and yet providing a reliable operation when in use.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to antennae and, more particularly, to a telescoping antenna capable of withstanding severe environmental conditions.

It has been a long, outstanding problem to design an effective high frequency antenna due to the stringent bandwidth requirements, the need for near isotropic gain, and the large physical dimensions associated with the lower end of this frequency band. The erectable antenna is a logical choice for this function because of its excellent performance when deployed and because it is inherently suited to providing survivability from severe nuclear threats.

During an attack it would be extremely desirable to protect the antenna within a buried structure from thermal radiation, flying debris effects and dynamic air-pressure load. However, this debris poses another difficult problem for the construction of the antenna. Furthermore, the erectable or pop-up antenna is wrought with additional severe mechanical problems.

For example, among the critical problems arising are the following: 1. The erection mechanism must be of sufficient power to supply the tremendous lift capacity to permit debris penetration; 2. The cover or closure protecting the antenna must be capable of preventing deterioration of the antenna from multiple attacks, shock, debris, impact, over-pressure and ablation from radiation and fireball. Furthermore, secure locking with a positive release is also necessary; 3. The erection element must be of sufficient length to clear the debris and yet be of sufficient stiffness to permit penetration. Also, integrity under severe horizontal and vertical shock load is essential in the retracted position; and, inadvertent erection must be held to a minimum.

It can therefore be clearly seen that the problems of producing a telescoping or erectable antenna which is capable of survivability during extreme conditions is a complicated procedure.

SUMMARY OF THE INVENTION

The instant invention sets forth a survivable telescoping antenna which overcomes the problems set forth hereinabove.

The instant antenna is made up of an outer casing having plurality of telescoping cylinders nested therein. The number of erecting cylinders is a function of the required debris penetration depth. A variety of individual power systems or numerous combinations thereof are available to provide the power solution for the erection of the instant antenna. It has been found that a hydraulic or pneumatic power system provides the utmost power source with the most reliable performance.

Typical hydraulic cylinder design, however, cannot be employed successfully under the severe design loading conditions encountered with the telescoping antenna of this invention because the extreme tolerance requirements over the full length of the cylinders make manufacturing costs prohibitive. To overcome this problem the individual cylinders are constructed to easily achievable tolerances, leaving a considerable amount of space between the cylinders. The cylinders or tubes are then restrained horizontally by bearing surfaces. These bearing surfaces, preferably, take the form of bearing rings. The number and spacing of the rings used to prevent buckling in the cylinder span depend upon the type of rock or medium in which the antenna is installed and the design hardness level. The rings also serve a second purpose when the inter-cylinder spaces are filled with either oil or a viscous fluid; that of rate limiting the erection by bleeding fluid passed the bearing rings. This fluid in the antenna cylinders beside rate limiting also serves to protect the metal surfaces from moisture, lubricates the sliding parts, and can possibly aid in attenuating the shock loads, both vertical and horizontal, by compression of air and fluid in the voids between the cylinder walls.

Another consistent problem encountered in the erectable or silo protected antenna has been shock mounting of the internal elements and the "up-lock" design. To prevent damage to the element or antenna radiator, rubber rebound or shock pads are placed at the bottom of each free cylinder. Up-locking the erected elements of the telescoping antenna can be handled in several ways. Wedging of the bearing rings between the cylinder walls when the elements reach full extension is a simple approach. Another method, and preferably the better, is the utilization of bellville centering springs with a locking pin associated therewith for holding the cylinders in the up or extended position.

Perhaps the most vulnerable component in an erectable structure is the closure, since it is normally exposed to all direct effects of a blast or the like. In addition, submerging the antenna several feet greatly reduces the g loads induced by the air over pressure wave. The most effective closure is a domed or hemispherical closure which can be released by internal activation. Such a closure is held in place by a multiple spring lock which is unlocked by deflection of finger springs by the top erecting element.

The specific type of radiator utilized with this antenna may vary with its intended use and can easily be adapted for mounting on the telescoping antenna of this invention.

It is therefore an object of this invention to provide a survivable telescoping antenna which is capable of being erected through vast amounts of accumulated debris.

It is another object of this invention to provide a survivable telescoping antenna which utilizes a cover or closure which is capable of surviving nuclear criteria as well as severe natural environment.

It is a further object of this invention to provide survivable telescoping antenna whose internal elements are of sufficient length to penetrate the accumulated debris and yet are stiff enough in bending to withstand any horizontal shock forces and those caused by various lopsided distribution during erection.

It is still another object of this invention to provide a survivable telescoping antenna which is highly reliable in operation and yet which is economical to produce and which utilizes conventional currently available materials that lend themselves to standard mass-producing manufacturing techniques.

For a better understanding of the present invention together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

DESCRIPTION OF THE DRAWING

FIG. 1 is a pictorial view of the survivable telescoping antenna of this invention enclosed within its outer casing or silo and located underground;

FIGS. 2-4 are a pictorial view of the survivable telescoping antenna of this invention in various positions of erection;

FIG. 5 is a pictorial view, partly in cross-section, of the various erectable elements, spacer rings and locking feature of the survivable telescoping antenna of this invention;

FIG. 6 is a pictorial view, shorn partly in cross-section, of the closure element in position on the survivable telescoping antenna of this invention;

FIG. 7 is a side elevational view, shown in cross-section, of the survivable telescoping antenna of this invention in its retracted position;

FIG. 8 is a side elevational view, shown partly in cross-section, of the survivable telescoping antenna of this invention in a partially erected position;

FIG. 9 is a side elevational view, shown partly in cross-section, of the survivable telescoping antenna of this invention in its fully erected position;

FIG. 10 is a pictorial view of the shear pin bearing ring utilized with the survivable telescoping antenna of this invention;

FIG. 11 is the pictorial view, shown partly in cross-section, of the floating bearing ring utilized with the survivable telescoping antenna of this invention;

FIG. 12 is a side elevational view, shown in cross-section, of the bearing ring with a ball-lock and release concept utilized with the survivable telescoping antenna of this invention;

FIG. 13 is a side elevational view, shown in cross-section, of the up-lock mechanism utilized with the survivable telescoping antenna of this invention;

FIG. 14 is a side elevational view, shown in cross-section, of the closure utilized with the survivable telescoping antenna of this invention;

FIGS. 15-17 are pictorial views of the HF radiators utilized with the survivable telescoping antenna of this invention; and

FIG. 18 is a side elevational view, shown in cross-section, of the UHF radiator utilized with the survivable telescoping antenna of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference is now made to FIGS. 1-4 of the drawing which disclose in pictorial fashion the operation of the telescoping antenna 10 of this invention. This antenna 10 is capable of being embedded within the ground 11 in order to survive any form of attack or extreme natural environment. Yet, as shown in FIGS. 1-4, upon demand the antenna 10 of this invention can be activated to penetrate through vast amounts of debris 13 which has fallen thereupon, and extend to the fully operable position, shown in FIG. 4. A more detailed description of the operation of the instant invention will be set forth hereinbelow.

A detailed showing of the features which make up the telescoping antenna 10 of this invention can best be seen in FIGS. 5-9. The antenna 10 is made up of an outer casing or silo 12 having a plurality of telescoping cylinders or elements 14 and 16 nested therein. The silo 12 and cylinders 14 and 16 are made of any suitable material, such as steel, and although only two such cylinders 14 and 16 are shown in the drawing any suitable number may be used depending upon the application of antenna 10 or the required debris penetration depth. In addition to the erecting elements or cylinders 14 and 16, a radiating element such as shown in FIGS. 15-18 is mounted upon cylinder 16 and is erected last in sequence. These radiators vary greatly depending upon their intended usage. A closure element 18 protects the radiator from damage during its retracted position.

There are several conventional power systems which may be used with the telescoping antenna 10 of this invention. For example, the power source 19 may be in the form of a hydraulic lift device, electro-mechanical lifting means, pneumatic lifter, jack screw, mechanical spring or ballistic charge. Since the specific power source does not constitute part of the instant invention, it is not disclosed in a detailed manner. However, it has been found that the combination of a hydraulic-pneumatic power source 19 is most desirable with the telescoping antenna 10 of this invention.

As shown in FIGS. 5 and 7-9, the cylinders 14 and 16 are not in the form of conventional hydraulic cylinders, since such cylinders require manufacturing with extreme tolerances, thereby making cylinder manufacturing costs prohibitive. The instant invention utilizes individual cylinders or elements 14 and 16, manufactured to easily achievable tolerances, leaving a considerable amount of space 20 between the cylinders 14 and 16 and the outer casing 12. The cylinders 14 and 16 are then held in place horizontally by any suitable bearing means, such as bearing rings 22. These bearing rings 22, best shown in FIG. 10, are easily fabricated and provide superior base support when the telescoping antenna 10 is in the erected position. A shear pin 24 is utilized to affix these bearing rings 22 to the cylinders 14 and 16, respectively. Thus, as shown in FIGS. 5 and 7-9, as the cylinders 14 and 16 sequentially telescope to the fully extended position (FIGS. 4 and 9) the bearing rings 22 shear from cylinders 14 and 16 upon abutting outstanding surfaces 26 on outer casing 12 and cylinder 14. Bearing rings 22 further act as a stop means when the antenna 10 is fully erected. FIG. 11 shows a tethered bearing ring 28, while FIG. 12 shows a ball lock bearing ring 30 which, although not quite as reliable in operation as bearing rings 22, may under certain instances be utilized in place of bearing rings 22. The number and spacing of bearing rings 22 depends upon the type of horizontal support required or on the type of rock or medium the antenna 10 is to penetrate. Bearing rings 22 are made of any suitable material, such as steel or high density plastic, such as fiberglass or special density polyethylene. The rings 22 are further utilized to limit the rate of erection of the antenna 10 when the inter-cylinder spaces 20 are filled with either oil or a viscous fluid by bleeding fluid past the rings 22.

Another problem solved by the telescoping antenna 10 of this invention is the design of shock mounting the internal cylinders 14 and 16. Sufficient clearance 31 between the cylinders 14 and 16 and the closure element 18 permits free rebound of these elements. This displacement will tend to be damped by compression of the air above the cylinders and shear in the wall fluid/bearing interfaces. Rebound of the elements 14, 16, after initial displacement is caused by gravity fallback, silo return, and expansion of the air above the elements after shock compression. To prevent damage to the elements or cylinders 14 and 16 or to the radiator attached thereto, rubber rebound or shock pads 36, as shown in FIGS. 5 and 7-9 are placed at the bottom of each free cylinder 14 and 16.

Upon the full erection of cylinders 14 and 16 a locking mechanism is required to hold the cylinders in the full-up position. FIG. 13 shows a bellville centering spring locking mechanism 38 which can be activated by a fluid under pressure in order to extend or retract locking element 40. In order to secure cylinders 14 and 16 in the up position the locking element 40 is extended so as to rest against the top edge of the outer casing 12 or other cylinder. Another method of up-locking the erected elements is by wedging the bearing rings between the cylinder walls when the elements reach full extension; however, this simple approach is not quite as effective as locking mechanism 38 described heretofore.

During erection of cylinders 14 and 16, they are controlled in their sequencing operation by varying the respective cylinder areas and by the use of a vertical standpipe 41 located in the center of antenna 10. In addition to the sequencing function, the standpipe 41 acts as a guide for the inner cylinder 16 and is further used to house the antenna transmission line (not shown).

The most vulnerable component of the instant invention is the closure element 18 best shown in FIG. 14. This closure element 18 is normally exposed to all direct nuclear effects or severe natural environment. It is most desirable that the closure element 18 is also used as part of the debris penetrator during erection of the antenna 10. The most effective closure element 18 is of a domed or hemispheric configuration which can most effectively transmit over-pressure loads onto the silo or outer casing wall 12 axially. This closure element 18 is made up of outer dome 42 having an elastomer pad 44 encased therein with a load carrying ring and spring lock 46 securing the closure element 18 to the innermost cylinder 16. The closure element 32 is released in the last step in the erection of cylinder 16 by the internal force of the inner cylinder 16 abutting the spring lock 46.

Reference is now made to FIGS. 15-17 which show a plurality of HF radiators which can be installed in a conventional manner on the top of the innermost erectable cylinder 16. A self-extending radiator 48 is shown in FIG. 15 and although somewhat flexible, its resistance to adjacent site attack would be low. To more complex radiators take the form of a normal mode helex radiator 50, shown in FIG. 16, and an isolated mast radiator 52, shown in FIG. 17. Both these radiators, 50 and 52, would also be integral with the innermost erectable cylinder 16. The stiff fiberglass element 54 of radiator 50 can be made extremely strong providing a considerable degree of adjacent site kill protection. Furthermore, the normal mode helex radiator 50 can be made to resonate at lower frequencies than an equivalent stub radiator, since much of the inductance normally included in a tuner is actually distributed in the element itself. The isolated mast concept of FIG. 17 is a method of feeding the HF antenna where the transmission line is fixedly coupled to the antenna at all times rather than using a slip-ring type feed, such as the normal mode helex radiator.

FIG. 18 shows a UHF radiator 56 to be utilized with the antenna 10 of this invention. This radiator 56 is a short shunt fed stub which has extremely high survivability. If, however, bandwidth is a problem an element, such as a fiberglass encased biconical, could be used.

In use the telescoping antenna 10 of this invention is embedded in its retracted position within the earth 12, as shown in FIG. 1. When it becomes necessary to erect the antenna 10, any suitable power source 19, such as a hydraulic pneumatic power source is activated. This power source 19 is utilized to erect cylinder 16 to the position shown in FIGS. 3 and 8. As cylinder 16 extends, the bearing rings 22 upon abutting outstanding element 26 on outer casing 12 shear from cylinder 16 allowing further extension of cylinder 16 until all three bearing rings 22 are in the abutting position shown in FIG. 8. In this fully extended position locking elements 40 are extended securing cylinder 16 in the full up position. During this erection procedure the upper end of cylinder 16 abuts the inner spring lock 46 of closure element 18. This action retracts spring lock 46 on closure element 18 and upon further erection thereof ejects closure element 18, as shown in FIG. 3. Continued activation of the power source extends inner cylinder 14 in the same manner as cylinder 16 until the radiator attached thereto is exposed for utilization thereof, as shown in FIGS. 4 and 9.

It is this unique relationship between the various elements of the instant antenna 10 which allow for a high degree of survivability for the antenna during its retracted position and yet almost immediately upon demand this antenna 10 is capable of operating in a completely reliable manner.

Although this invention has been described with reference to a particular embodiment, it will be understood to those skilled in the art that this invention is also capable of a variety of alternative embodiments within the spirit and scope of the appended claims.

Claims

We claim:

1. A survivable telescoping antenna comprising an outer casing, at least one element nested within said outer casing, a shock pad mounted at the bottom of said element, a power source operably connected to said element, a space between said outer casing and said element, at least one bearing ring secured to the external surface of said element by a shear pin for supporting said element, said bearing ring located in said space between said element and said outer casing, a radiator mounted on said element, a closure element mounted on said outer casing for protecting said radiator in its retracted position and a locking mechanism mounted on said element, whereby upon activation of said power source, said element extends from said outer casing thereby ejecting said closure element and exposing said radiator.

2. A survivable telescoping antenna as defined in claim 1 further comprising a vertical standpipe fixedly secured to the base of said outer housing and located in the center of said element.

3. A survivable telescoping antenna as defined in claim 2 wherein said closure element is of a domed configuration and has a spring lock thereon for engaging said outer casing, whereby upon internal abutment by said element during erection thereof said spring lock is released and said closure element is ejected.

4. A survivable telescoping antenna as defined in claim 5 wherein said element is of a cylindrical configuration.

5. A survivable telescoping antenna as defined in claim 4 further comprising a plurality of said elements each nested within one another with said radiator mounted upon said innermost element.

6. A survivable telescoping antenna as defined in claim 5 further comprising a plurality of bearing rings supporting each of said elements.

7. A survivable telescoping antenna as defined in claim 6 wherein said locking mechanism is in the form of a bellville centering spring locking mechanism.