US3754268A

US3754268A - Submarine-to-satellite communications antenna

Info

Publication number: US3754268A
Application number: US00287309A
Authority: US
Inventors: J Boyns
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1972-09-08
Filing date: 1972-09-08
Publication date: 1973-08-21
Anticipated expiration: 1990-08-21

Abstract

A phased-array antenna system for an SHF communications link between submarines and earth-orbiting satellites. The compact antenna system is mounted in the head of a submarine periscope and provides increased data rate, low-sidelobes, variable beam control, multiple-beam capability, and circular polarization. RF energy to be transmitted is conducted from transmitting means in the submarine through a waveguide run the length of the periscope to the antenna system which includes a high-power switch to commute the energy to a four-port hybrid matrix. The matrix feeds selectively predetermined phase progressions of the energy to the radiating array which comprises a plurality of probe-fed, cavity elements.

Description

wir States Patent [191 Boyns Aug. 21, 1973 [75] Inventor:

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

[22] Filed: Sept. 8, 1972 [21] Appl. No.: 287,309

Jerry E. Boyns, San Diego, Calif.

52 U.S.Cl 343/709, 343/872, 343/854 511 Int.Cl. H01q 1/34 581 FieldofSearch 343/709,?10, 872,

[56] References Cited UNITED STATES PATENTS 3,495,261 2/1970 Lastinger et al. 343/709 Primary Examiner-Eli Lieberman Attorney-R. S. Sciascia, George J. Rubens et al.

[5 7 ABSTRACT A phased-array antenna system for an SHF communications link between submarines and earth-orbiting satellites. The compact antenna system is mounted in the head of a submarine periscope and provides increased data rate, low-sidelobes, variable beam control, multiple-beam capability, and circular polarization. RF energy to be transmitted is conducted from transmitting means in the submarine through a waveguide run the length of the periscope to the antenna system which includes a high-power switch to commute the energy to a four-port hybrid matrix. The matrix feeds selectively predetermined phase progressions of the energy to the radiating array which comprises a plurality of probefed, cavity elements.

4 Claims, 5 Drawing Figures PATENTED BB2! 8973 SHEET 1 BF 2 FIG.2

FIG.1

PATENTEUAusZI ms 3754.268

SHEEI 2 0f 2 20 RELATIVE POWER ONE WAY (an) 38 o o 0 0 72 36 O 36 72 FIG. 4

RELATIVE POWER ONE WAY (db) IO 2O WM WMX SUBMARINE-TO-SATELLITE COMMUNICATIONS ANTENNA BACKGROUND OF THE INVENTION At the present time, an SHF link for providing communication between submarines and earth-orbiting satellites is not availablealthough the need for such a link does currently exist. The inventive concept to be disclosed herein relates to a novel phased array antenna which can provide such a link and which can replace the periscope-mounted radar ranging antenna currently found in submarines but which cannot provide a submarine-to-satellite communications link.

SUMMARY OF THE INVENTION A submarine-to-satellite antenna system for an SI-IF communications link between a submarine and an earth-orbiting satellite is disclosed. The antenna system comprises a compact, relatively small unit which is mounted in an aperture in the head of a submarine general purpose periscope. RF energy from a transmitter source in the submarine is coupled through a waveguide run the length of the periscope to a high-cover switch in the unit to commute the energy to a beamforming hybrid matrix which provides selectively predetermined phase progressions across the radiating aperture of the antenna. The radiating array comprises a plurality of probe-fed, cavity elements. A radome is mounted in the aperture to protect the antenna system from the environment. In operation the multiple beam capability can be used as a broad beamwidth antenna to acquire the satellite, and after the acquisition, full power can be radiated by a high-gain, narrow beam.

STATEMENT OF THE OBJECTS OF INVENTION The primary object of the present invention is to provide a submarine-to-satellite SHF communications link including a phased-array antenna and featuring increased data rate, low-sidelobes, variable beam control, multiple-beam capability, and circular polarization.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF TI-IE DRAWINGS FIG. 1 is a partial cut-away, side view of a generalpurpose, submarine periscope having mounted in the head thereof a novel antenna system to be described herein;

FIG. 2 is a front view of the apparatus of FIG. '1;

FIG. 3 is an isometric view of one of the cavity elements of the radiating array 18; and,

FIGS. 4 and 5 are exemplary radiation patterns obtained with the unique antenna system to be described hereinafter.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present inventive concept comprises novel phased-array antenna apparatus intended to be used primarily in submarine-to-satellite SI-IF communications systems to achieve the following operational characteristics: increased data rate, low-sidelobes, variable beam control, multiple-beam capability and circular polarization. FIG. 1 represents the preferred embodiment of the concept wherein a unique, compact, phased-array antenna system is mounted in an aperture in the head of a submarine periscope to provide an SH F communications link between the submarine and an earth-orbiting satellite.

As can be appreciated from FIG. 1, the apparatus comprises a relatively simple structure incorporating as one of the main features thereof a submarine, general purpose periscope head 10 as the support structure for a unique phased-array antenna system which is generally located and mounted in an aperture 12 located below the optical apparatus 14 of the periscope. The antenna system comprises, in part, an electromagnetic window or radome 16 which is rigidly supported in the aperture 10 in the periscope head. The radome is rectangular and is mounted at substantially 45 with respect to the vertical axis of the periscope.

One side of the radome is exposed to the atmosphere and is mounted substantially flush with the outer portion of the aperture. Since the antenna system will be exposed to adverse ocean and sea environments, the radome 16 must be capable of withstanding diverse elements such as high external pressure, high humidity, and high external temperatures. Fused quartz can be used advantageously where high external pressures and humidity are encountered, and glass-reinforced aluminum phosphate can be used where high external temperatures are encountered. For deep-sea submergence where high humidity is experienced, a thin coating of teflon or some other moisture resistive material is required.

A radiating array 18 which is also rectangular is positioned in a contiguous manner with the opposite side of the radome and is rigidly supported in the periscope head. The array comprises a plurality of probe-fed, cavity elements which are arrayed in the rectangular area 18 in a three-column, four-row manner. The radiating elements of the array are described generally in The Bell Systems Technical Journal, Vol. XLII, July 1963, pp. 869-897, and FIG. 3 illustrates in an isometric view one of the elements, 180.

The dimensions of the aperture of the element are selected such that two cross-polarized modes (TE and TE can propagate. The length W, of the cavity is ad justed to produce a phase differential between the two polarizations to produce circularly polarized fields at the aperture.

The narrow dimension W is adjusted relatively close to cutoff, and the depth d of the cavity is adjusted to produce the preferred circular polarization. The lengths L and L, of the probe are adjusted to provide the preferred polarization and the preferred (best) impedance match for the element from a SO-ohm coaxial input line to free space. The primary advantage offered by an array of such elements is that it will provide more than one beam position in the quadrant from horizon to zenith by simply activating the high-power switch 22 to select one of the four probes of the matrix 20.

The four-port hybrid matrix 20 or Butler matrix is electrically connected to and rigidly supported behind the array structure 18 in a contiguous manner with one side thereof. The Butler matrix is a well-known device (Electronic Design, April 1961, p. 179) and feeds phase progressions of RF energy to selectively predetermined ones of the cavity elements 180 of the array 18 whereby four separate beams are provided for sector coverage. The four beams can cover a quadrant in either the elevation or azimuth planes with a minimum of zero absolute gain and with a fan beam being provided in the plane opposite to that being scanned.

Mounted below the hybrid matrix 24 is a conventional high-power switch 22 which has each of its four output ports connected to a different one of the four input ports of the matrix by means of a corresponding coaxial cable 22a. The switch can comprise a singlepole, four-throw device which commutes RF energy to one of four possible coaxial outputs.

The RF energy is coupled to the switch input from transmitter apparatus (not shown) located within the submarine. A waveguide run 24, approximately the length of the periscope, is connected between the switch and the transmitter to accomplish the above.

In operation, RF energy from the transmitter apparatus is conducted through the waveguide run 24 to the high-power switch 22. The selected output port of the switch couples its output to a corresponding input port of the matrix 20 wherefore it provides a selectively predetermined phase progression across the radiating array 18.

One of the four possible main beams is then radiated therefrom depending upon which of the four input ports of the matrix has been energized. A detecting device can be connected to any one of the four input ports of the matrix to facilitate selection of the radiated beam.

As stated earlier the matrix and array can provide four separate beams for sector coverage and the four beams can cover a quadrant in either the elevation or azimuth planes with a minimum of zero absolute gain.

FIGS. 4 and 5 represent typical radiation patterns as measured for the system of FIG. I and 2. Specifically, FIG. 4 shows in graphical form the four beams as measured with the antenna receiving vertically polarized RF energy, and FIG. 5 shows a measured pattern with the antenna receiving rotating linearly polarized RF energy.

Thus it can be seen that a novel, relatively simple system has been disclosed for providing SHF communications between a submarine and a satellite by means of a phased-array antenna apparatus mounted and supported in an all-purpose submarine periscope. The system provides increased data rate, low-sidelobes, variable beam control, multiple-beam capability, and circular polarization.

Obviously many modifications and variations of the present invention are possible in the light of the-above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

For example, variations in the design of the radiating aperture could allow for mounting of the radome in the periscope head at more nearly a perpendicular angle (less than 45). Also, other types of hybrid matrices could be used advantageously to allow for tilting of the four beams at various angles above the horizon, and matrices having more than four ports could be used in conjunction with radiating apertures having the same number of radiators in the elevation plane to provide sharper beams for more precise satellite contact.

Finally, the entire system could be replaced with a non-resonant waveguide array of cross-slots which would be designed to have a single main beam at certain elevation angles. However, this array has a major disadvantage in that one-half the transmitted power must be dumped into a load and also each operating area for the submarine between the equator and the Artic would require a new antenna with a given elevation angle for the main beam.

What is claimed is:

l. A periscope mounted phased-array antenna system for use in submarine-to-satellite communication systems and comprising:

a general-purpose, submarine periscope,

said periscope having a head portion with an aperture on one side and near the top thereof;

RF energy radiating aperture means mounted and rigidly supported in said aperture whereby said means can radiate energy into the atmosphere;

energy feed means mounted and rigidly supported inside said periscope head and being electrically connected to said radiating aperture means;

transmitter means located inside said submarine; and

waveguide means connected between said transmitter means and said energy feed means to conduct RF energy to said radiating aperture means.

2. The system of claim 1 wherein said radiating aperture means comprises a rectangular-shaped, electric radome mounted substantially flush with respect to the exterior of said aperture, and further including a rectangular-shaped array of probe-fed, cavity elements mounted behind said radome and substantially inside said periscope head.

3. The system of claim 2 wherein said energy feed means comprises a four-port hybrid matrix mounted behind said array of probe-fed cavity elements to energize selectively predetermined ones of said cavity elements.

4. The system of claim 2 wherein said energy feed means comprises a Butler matrix.

Claims

1. A periscope mounted phased-array antenna system for use in submarine-to-satellite communication systems and comprising: a general-purpose, submarine periscope, said periscope having a head portion with an aperture on one side and near the top thereof; RF energy radiating aperture means mounted and rigidly supported in said aperture whereby said means can radiate energy into the atmosphere; energy feed means mounted and rigidly supported inside said periscope head and being electrically connected to said radiating aperture means; transmitter means located inside said submarine; and waveguide means connected between said transmitter means and said energy feed means to conduct RF energy to Said radiating aperture means.