Easyly deployable phased antenna for a spacecraft and system of such antennas

Abstract

An antenna is made from strips of a shape-memory alloy or other resilient material acting as a spring with attached branches that constitute individual monopole antennas. In the folded state, the antenna looks like a strip roll and can be placed on a satellite. When in orbit, the antenna unfolds after the roll retention mechanism is released and orderly unfolds unrolling from a support frame or otherwise extends. The proposed design of monopole branches utilizes conductors of minimum length and achieves maximum directivity. Each monopole branch is connected to the signal receiver/transmitter by signal conduit elements. A system may include at least two such unfolding antennas thus achieving even greater operational effectiveness in regard to signal steerability, interference suppression and reduced moment of the satellite inertia. To prevent problems, additional measures are used that prevent unwinding of inner layers of the roll before the outer layer is extended.

Claims

1. A self-deploying antenna for spacecraft, comprising: at least one pair of transversal members, each of the transversal members of the at least one pair of transversal members being made of a first self-straightening metal strip; a mounting chamber for mounting the antenna to the spacecraft, wherein each of the transversal members of the at least one pair of transversal members have a first end and an opposite second end, the first end attached to the mounting chamber and the second end being free; and a plurality of monopole electric vibrators made of a second self-straightening metal strip and attached to the transversal members of the at least one pair of transversal members, wherein a first joint angle between one transversal member of the at least one pair of transversal members and at least one of said monopole electric vibrators is close to zero when the antenna is in un-deployed transportation state, and a second joint angle between another transversal member of the at least one pair of transversal members and at least one monopole electric vibrator associated with said another transversal member is close to zero when the antenna is in the un-deployed transportation state, the first joint angle between the one transversal member and the at least one monopole electric vibrator associated with said one transversal member is greater than zero when the antenna is in a deployed state, and the second joint angle between the another transversal member and the at least one monopole electric vibrator associated with said another transversal member is greater than zero when the antenna is in deployed state, and wherein monopole electric vibrators associated with said one transversal member and monopole electric vibrators associated with said another transversal member are configured to unbend in different direction respectively.

2. The self-deploying antenna in accordance with claim 1, wherein the monopole electric vibrators, which are attached to the transverse member, unbend in different directions.

3. The self-deploying antenna in accordance with claim 1, wherein a member, which is attached to one of the monopole electric vibrators of the transverse member, unbends at an angle to the said monopole vibrator.

4. The self-deploying antenna in accordance with claim 1, wherein the monopole electric vibrators, which are attached to the transverse member, unbend into different planes.

5. The self-deploying antenna in accordance with claim 1, wherein the antenna further comprises a guiding element for guided unrolling of the antenna.

6. The self-deploying antenna in accordance with claim 1, wherein plural of monopole electric vibrators, which are attached to any one transverse member of the pair of transverse members unbend in different directions.

7. The self-deploying antenna in accordance with claim 1, wherein at least one monopole electric vibrator, which is attached to another monopole electric vibrator of the any one of the pair of transverse members, is at an angle when unbent to said at least one monopole electric vibrator.

8. The self-deploying antenna in accordance with claim 1, wherein plural of the monopole electric vibrators, which are attached to at least any one transverse member of the pair of transverse members, unbend into different planes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The following are the drawings for explanation of the invention:

(2) FIG. 1: An example of how an antenna is rolled up on an antenna support in the satellite camera;

(3) FIG. 2: An example of attachment of antenna roll-up support to the satellite;

(4) FIG. 3: A guiding element for deflection of unfolding antenna strip members;

(5) FIG. 4: a single phased array antenna in unfolded state;

(6) FIG. 5-8 presents examples of attachment methods of monopole electric vibrators of a phased array antenna to the transversal antenna member;

(7) FIGS. 9a and 9b presents an example of attachment method of monopole electric vibrators to the transversal antenna member via an insulator and a hinging element and wiring to the signal transmission line respectively from side and from above;

(8) FIG. 10: An example of a phased array antenna system.

DETAILED DESCRIPTION OF THE INVENTION

(9) FIG. 1 and FIG. 2 presents methods of attachment of strip elements (2, 2, 2) of a phased array antenna (1) as designed for nanosatellites to the antenna (1) mounting chamber (3) for mounting the antenna (1) to a nanosatellite, but not limited to winding of the antenna (1) strip elements (2, 2, 2) around the mounting chamber (3), rolling of the antenna strip members (2, 2, 2) into a roll for placement inside the mounting chamber (3), and folding of the antenna strip elements (2, 2, 2) for placement inside the mounting chamber (3). In all cases, one end of the antenna transverse strip member (2) is fixed to the mount in the nanosatellite mounting chamber (3) by a fixing accessory (5) and the other end is free. The antenna (1) strip members (2, 2, 2) are securely held in a collapsed state occupying the least space volume and the monopole electrical vibrators (2, 2) and the transverse strip member (2) make an angle close to 0 at the line of attachment until the satellite reaches the intended orbit. Upon reaching the deployment location, 30 the holding element (4) is released and the antenna stripe members (2, 2, 2) unroll until the antenna gains the intended shape. In the unfolded state, the antenna (1) transverse member (2) and the monopole electric vibrators (2, 2) make an angle larger than 0 at the line of attachment.

(10) In all cases, the antenna (1) comprises unfolding members (2, 2, 2) and the mounting chamber (3) for mounting to the nanosatellite, where the phased array antenna (1) strip elements (2, 2, 2) can be fastened to it, rolled upon it and subsequently released or can be placed inside the said mounting chamber (3) for mounting to the satellite. The transverse strip members (2, 2, 2) comprises a transverse strip member (2) and at least one additional strip member (2, 2) hingedly connected to the transverse strip member (2) which forms a distinct monopole electric vibrator of the antenna (1).

(11) FIG. 3 presents an example of a guiding element (31) for unrolling of the phased array antenna (1) strip members (2, 2, 2). This element (31) is intended to ensure orderly unrolling of the antenna (1) strip elements (2, 2, 2) by preventing the inner layers to unroll before the outer layers. This element (31) is attached close to the free end of the transverse strip element (2), which is located in the inner part of the strip elements roller. A sticky or pasty material between the roll layers can also be used for this purpose.

(12) FIG. 4 shows an unfolded strip part of the phased array antenna (1) consisting of a fixing accessory (5) for attachment of the antenna (1) to the antenna (1) mounting chamber (3), the transverse strip member (2), and at least two branching monopole electric vibrators (2, 2). The antenna may also comprise two transverse members (2) attached to the satellite, each of which has an attached monopole electric vibrator (2, 2). In this case, both transverse members will unfold from the mounting chamber (3) in opposite directions in the same way as in case of one transverse member, only in opposite directions.

(13) At least two said branching monopole electric vibrators (2, 2) are fastened to the transverse strip member (2) via lightweight spring elements or lightweight articulated elements (5, 5) for easy unbending to essentially upright position relative to the transverse strip member (2). Although the drawing shows only two branching strip elements (2, 2), their number can be much larger and they can be mounted on both sides of the transverse strip member (2).

(14) The phased array antenna (1) with two branching monopole electric vibrators (2, 2) can receive/transmit a circularly polarized signal or simultaneously receive/transmit two signals of different linear polarization.

(15) All strip members (2, 2, 2) of the phased array antenna (1) can be made of an electrically conductive shape-memory alloy or other electrically conductive resilient material such as a steel band. The transverse strip member can be provided with additional signal conduits (91, 93), such as cables or current conducting paths. The antenna (1) of this type includes conductors of minimum size since the transverse belt element (2) performs the function of the dipole arm.

(16) FIGS. 5-8 show some examples how monopoly electric vibrators (52, 62, 62; 72, 72, 82, 82) can be attached to the transverse strip member (2) of the phased array antenna (1).

(17) FIG. 5 shows the simplest assembly of the transverse strip member (2) of the phased array antenna (1) and a monopole electric vibrator (52), where polarization of the phased array consisting of a transverse strip element and a monopoly vibrator (52) is linear. The electrical vibrator (52), the folding axis of which is parallel to the transverse strip element (52) plane, unbends after the transverse element (2) is unrolled. The planes of both members (2, 52) in extended state are orthogonal to each other.

(18) FIGS. 6-8 show cases, when monopole electric vibrators (62, 62, 72, 72, 82, 82) are fixed to the transverse member (2) of the phased array antenna (1) in pairs next to each other. Each said vibrator (62, 62, 72, 72, 82, 82) in a pair has a linear polarization perpendicular to that of each other and a pair of vibrators has a circular polarization.

(19) FIG. 6 shows monopole electric vibrators (62, 62), folding axes of which are perpendicular to the plane of the transverse stripe member (2) and which unbend to 45 degrees when the transversal strip (2) is unrolled. If vibrators are not stacked upon each other in the folded state, then one vibrator (62) tilts to 45 degrees, and the other (62) tilts to 125 degrees. In the folded state, the planes of all three said strip elements (2, 62, 62) are parallel. In the unfolded state, the planes of the vibrators (62, 62) are parallel and perpendicular to the plane of the transverse strip member (2).

(20) The electric vibrator (72) in FIG. 7, the folding axis of which is perpendicular to the plane of the transverse stripe member (2), unbends to 90 degrees when the transversal strip (2) is unrolled. The electric vibrator (72), the folding axis of which is perpendicular to the plane of the vibrator (72), unbends to 90 degrees when the vibrator (72) is extended. The strip elements (2, 72, 72) are stacked upon each other in the folded state.

(21) FIG. 8 shows electric vibrators (82, 82) that unbend to 90 degrees when the transversal member (2) is unrolled. The folding axis of one electric vibrator (82) is perpendicular to the transversal member (2) plane, and the axis of the other vibrator (82) is parallel to the transversal member (2) plane. In the extended state, the plane of two strip members (2, 82) are parallel and perpendicular to the plane of the third strip member (82).

(22) FIGS. 9a and 9b present an example, where at least one monopoly electric vibrator (92) of the phased array antenna (1) is attached to the transversal strip member (2) via an electrically insulating element (94) and means (96) facilitating extension of the said monopole vibrator (92), such as a spring element. Additionally, at least one monopole vibrator of the antenna can be connected to the spacecraft signal receiver/transmitter via signal conduits (91, 93), such as cables, or electrical current conducting paths.

(23) FIG. 10 shows an example, where a system is constructed from phased array antennas (1) and consists of at least two transversal strip elements (2), which extend from the mounting chamber (3) for mounting to the spacecraft (101) and to which the monopole electric vibrators (2, 2, 2, 2) are attached. A satellite (101) may have more than two phased array antennas (1), depending on the structure of the satellite itself.

(24) Compared with conventional deployable nanosatellite monopole antennas, a phased array antenna according to the invention has a narrower field of view, higher gain factor, and ability to steer the beam by changing the signal phases of individual antenna elements.