KR101864052B1 - Dynamic polarization and coupling control for a steerable cylindrically fed holographic antenna - Google Patents

Abstract

Antennas for a cylindrical feed antenna and a method for using the same are disclosed herein. In one embodiment, the antenna comprises an antenna feeder for inputting a cylindrical feed wave and an adjustable slotted array coupled to the antenna feeder.

Description

[0001] DYNAMIC POLARIZATION AND COUPLING CONTROL FOR A STEERABLE CYLINDRICALLY FED HOLOGRAPHIC ANTENNA FOR A HORIZONTAL CIRCUITALLY DISTRIBUTED HORIZONTAL ANTENNA [0002]

Priority claim

This patent application is a continuation-in-part of U.S. Provisional Patent Application entitled " Polarization and Coupling Control from a Cylindrically Fed Holographic Antenna " filed on February 19, 2014, No. 61 / 941,801, as well as a corresponding patent application entitled " A Metamaterial Antenna System for Communications Satellite Earth Stations ", filed June 16, 2014, Priority is claimed on Serial No. 62 / 012,897, incorporated by reference.

Technical field

Embodiments of the present invention relate to the field of antennas, and more particularly, to embodiments of the present invention which are cylindrical antennas.

The Thinkcom products use a PCB-based approach and use a variable incline transverse stub or "VICTS" approach, which typically has two types of mechanical rotation functions: To achieve dual circular polarization in the Ka-band. The first type rotates one array for another, and the second type rotates both at azimuth. The primary limitation is the scan range (elevation between 20 and 70 degrees, not wide area possible) and beam performance (sometimes limited to Rx (reception) only).

&Quot; Radial line slot antenna for 12 GHz DBS satellite reception "by Ando et al. And Yuan et al.," A New Lady for High Power Microwave Applications " "Design and Experiments of a Novel Radial Line Slot Antenna for High-Power Microwave Applications" discusses various antennas. The limitations of the antennas described in these two articles are that the beam is formed at only one fixed angle. The feed structure described in these articles is a feed structure in which the first layer receives a pin feed to emit a signal toward the edge and bends the signal to the upper layer, and a folded dual layer transmitting from the periphery to the exciting center along the way. The slots are typically oriented in orthogonal pairs that provide fixed circular polarization during transmission and reverse in receive mode. Finally, the absorber terminates whatever energy remains.

"Scalar and tensor holographic artificial impedance surfaces", authors Fong, Colburn, Ottusch, Visher, and Sievenpiper. Although the zenpiper has shown how dynamic scanning antennas are achieved, the polarization fidelity maintained during scanning is questionable. This is because the required polarization control depends on the tensor impedance required by each radiating element. This is most easily achieved by element-wise rotation. However, as the antenna scans, the polarization at each element changes, and thus the rotation required also changes. Since these elements can not be fixed and dynamically rotated, there is no way to scan and maintain the polarization control.

Industry-standard approaches to achieving beam scanning antennas with polarization control use either some form of mechanical motion with mechanically rotated dishes or electron beam steering . The most expensive class of options is the full phased-array antenna. The dish can receive multiple polarizations at the same time, but it may require a gimbal to scan. More recently, the combination of mechanical movement in one axis with electron scanning in the orthogonal axis requires a high volume, which requires a small volume, but at the expense of beam performance such as the system of the Thinkcom or dynamic polarization control Resulting in a structure with an aspect ratio.

Previous approaches use a waveguide and a splitter feed structure to feed the antenna. However, the waveguide design has an impedance swinging near the broadband (band gap produced by the 1-wave periodic structure); Require bonding with different CTEs; Have an associated ohmic loss of the feed structure; And / or a ground-plane. ≪ Desc / Clms Page number 2 >

Antennas for a cylindrical feed antenna and a method for using the same are disclosed herein. In one embodiment, the antenna includes an antenna feed for inputting a cylindrical feed wave and a tunable slotted array coupled to the antenna feeder.

The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings of various embodiments of the invention, which are not to be taken to limit the invention and for the purposes of explanation and understanding only.
Figure 1 shows a top view of an embodiment of a coaxial feed used to provide a cylindrical wave feed.
Figures 2a and 2b show side views of an embodiment of a cylindrical feed antenna structure.
Figure 3 shows a plan view of one embodiment of a patch antenna, or scatterer, coupled in one slot.
Figure 4 shows a side view of a patch antenna fed into a slot that is part of a cyclically powered antenna system.
Fig. 5 shows an example of a dielectric material from which a power supply wave is launched.
Figure 6 shows one embodiment of an iris board showing the orientation of the slots and their orientation.
Figure 7 shows how the orientation of one iris / patch combination is determined.
Figure 8 shows a first set rotated at -45 degrees for a power feed vector and an iris grouped into two sets of a second set rotated at +45 degrees for a feed vector.
Figure 9 shows an embodiment of a patch board.
Figure 10 shows an example of an element with a patch in Figure 9 determined to be out of operation frequency.
Figure 11 shows an example of an element with a patch in Figure 9 determined to be at the frequency of operation.
Figure 12 shows the results of full wave modeling showing the electric field response to on and off control / modulation patterns for the elements of Figures 10 and 11. [
Figure 13 illustrates beam forming using an embodiment of a cylindrical feed antenna.
14A and 14B show patches and slots arranged in a honeycomb pattern.
Figs. 15A-15C illustrate a radial layout, associated control patterns, and patches and associated slots arranged in a ring shape to produce the resulting antenna response.
Figs. 16A and 16B show right circularly polarized light and left circularly polarized light, respectively.
Figure 17 shows a portion of a cylindrical power feed antenna comprising a glass layer containing a patch.
Figure 18 shows a linear taper of the dielectric.
19A shows an example of a reference wave.
Figure 19b shows the generated object wave.
Fig. 19C is an example of a resulting sine wave modulation pattern.
Figure 20 shows a modified antenna embodiment in which each side includes a step for allowing the traveling wave to be transmitted from the bottom layer to the top layer.

Embodiments of the present invention include an antenna design architecture that feeds an antenna from a center point to an excitation that is cylindrically or concentrically spread out from a feed point. The antenna is operated by arranging a plurality of cylindrically-fed subaperture antennas (for example, patch antennas) together with a feeder wave. In an alternative embodiment, the antenna is fed from a perimeter inward rather than a center outward. This can be helpful because it counteracts the amplitude excitation decay caused by scattering energy from the aperture. Scattering occurs in both orientations as well, but a natural taper caused by the concentration of energy in the feeder wave as it moves from within the periphery neutralizes the decreasing taper caused by the intended scattering.

Embodiments of the present invention are based on filling the aperture with two types of doubling (doubling) of the concentration and orthogonal set of elements typically needed to achieve holography And includes a holographic antenna. In one embodiment, one set of elements is oriented linearly at 45 degrees with respect to the feed wave and the second set of elements is oriented at -45 degrees with respect to the feed wave. Both types are illuminated by the same feed wave in a parallel plate mode launched by a coaxial pin feed in one form.

In the following description, numerous specific details are set forth in order to provide a more thorough description of the invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form rather than in detail in order to avoid obscuring the present invention.

Some portions of the detailed description that follow are provided in terms of algorithms and symbolic representations of operations on data bits in computer memory. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here and generally considered to be a self-consistent sequence of steps leading to a desired result. These steps are those that require physical manipulation of physical quantities. Generally, though not necessarily, these quantities take the form of electrical or magnetic signals that can be stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient sometimes to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, etc., in principle for reasons of common usage.

It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantity and are merely convenient labels applied to such quantities. As used herein, the term " processing "or" computing "or" calculating ", or "quot;," displaying ", and the like, may refer to data represented as physical (electronic) amounts in registers and memories of a computer system as well as computer system memory or registers or other such information storage, Refers to the acts and processes of a computer system or similar electronic computing device that manages and transmits data to and from other data represented as physical quantities within a transmission or display device.

An overview of an example of an antenna system

An embodiment of a metamaterial antenna system for a communication satellite earth station (ES) is described. In one embodiment, the antenna system is a mobile platform (e. G., Air, sea, or air) that operates using either Ka-band or Ku-band frequencies for private commercial satellite communications. (E. G., Ground, etc.) of a satellite earth station (ES). In addition, embodiments of the antenna system may also be used in earth stations other than mobile platforms (e.g., stationary or transportable earth stations).

In one embodiment, the antenna system uses surface scatter metamaterial technology to form and steer transmit and receive beams through separate antennas. In one embodiment, the antenna system is an analog system as opposed to an antenna system (e.g., a phased array antenna) that uses digital signal processing to electrically form and steer the beam.

In one embodiment, the antenna system comprises three functional subsystems: (1) a wave propagating structure of a cylindrical wave-fed architecture; (2) an array of wave scattering meta-material unit cells; And (3) a control structure for directing the formation of an adjustable radiation field (beam) from the meta-material scattering element using a holographic principle.

Wave Propagation Example

Figure 1 shows a top view of an embodiment of a coaxial feed used to provide a cylindrical wave feed. Referring to Fig. 1, the coaxial feeder includes a center conductor and an outer conductor. In one embodiment, the cylindrical wave-fed architecture feeds the antenna from the center point by excitation that spreads out cylindrically from the feed point. That is, the antenna fed in a cylindrical shape generates a concentric feeding wave going out. Nevertheless, the shape of the antenna fed into the cylindrical shape around the cylindrical feed may be circular, square or any shape. In another embodiment, the antenna fed in a cylindrical shape produces a feed wave traveling inward. In this case, the feed wave is most naturally generated from the circular structure.

Figure 2a shows a side view of one embodiment of a cylindrical feed antenna structure. The antenna uses a double-layer feed structure (i.e., a two-layer feed structure) to generate a wave going inward. In one embodiment, the antenna includes a circular outer shape, although this is not necessary. That is, a non-circular inward traveling structure may be used. In one embodiment, the antenna structure of Fig. 2A includes the coaxial feeder of Fig.

Referring to FIG. 2A, a coaxial pin 201 is used to excite the field to the lower level of the antenna. In one embodiment, the coaxial fin 201 is an easily available 50? Coaxial fin. The coaxial pin 201 is coupled (e.g., bolted) to the bottom of the antenna structure, which is a ground plane 202 that is conducting.

Disconnected from the conducting ground plane 202 is an interstitial conductor 203, which is an internal conductor. In one embodiment, the conducting ground plane 202 and the inserting conductor 203 are parallel to each other. In an embodiment, the distance between the ground plane 202 and the insertion conductor 203 is 0.1 to 0.15 inch. In another embodiment, the distance may be lambda / 2, Is the wavelength of the excitation wave.

The ground plane 202 is separated from the insertion conductor 203 via a spacer 204. In one embodiment, the spacers 204 are air-like spacers, such as foam or air. In one embodiment, the spacers 204 are made of plastic spacers.

The top of the inserting conductor 203 is the dielectric layer 205. In one embodiment, the dielectric layer 205 is plastic. Fig. 5 shows an example of a dielectric material from which a power supply wave is launched. The purpose of the dielectric layer 205 is to slow the traveling wave relative to the free space velocity. In one embodiment, the dielectric layer 205 slows the traveling wave by 30% relative to free space. In one embodiment, the range of refractive indices suitable for beamforming is 1.2 to 1.8, where the free space has a refractive index equal to 1 by definition. For example, other dielectric spacer materials such as plastics can be used to achieve this effect. It should be noted that materials other than plastics can be used as long as they achieve the desired wave slowing effect. Alternatively, a material having a distributed structure may be used as dielectric 205, such as a periodic sub-wavelength metal structure that may be defined, for example, mechanically or lithographically.

The RF array 206 is on top of the dielectric 205. In one embodiment, the distance between the insertion conductor 203 and the RF array 206 is 0.1 to 0.15. In another embodiment, the distance may be lambda eff / 2, where lambda eff / 2 is the median effective Wavelength.

The antenna includes sides 207 and 208. The side faces 207 and 208 are formed so as to allow a traveling wave feed from the coaxial fin 201 to propagate from the region under the inserting conductor 203 (spacer layer) to the region over the inserting conductor 203 (dielectric layer) Angled at an angle. In one embodiment, the angles of the sides 207 and 208 are at an angle of 45 degrees. In another embodiment, sides 207 and 208 may be replaced by continuous radii to achieve reflection. Although FIG. 2A shows an oblique side with an angle of 45 degrees, other angles may be used to achieve signal transmission from the lower level feed to the upper level feed. That is, considering that the effective wavelength in the bottom feed will generally differ from that in the top feed, some deviation from the ideal 45 ° angle can be used to help transmit from the bottom to the top feed level. For example, in another embodiment, a 45 degree angle is replaced with a single step as shown in Fig. 20, steps 2001 and 2002 are shown at one end of the antenna around the dielectric layer 2005, the insert conductor 2003, and the spacer layer 2004. [ The same two steps are at the other end of these layers.

The feed wave is supplied from the coaxial fin 201 and the wave is oriented concentrically from the coaxial fin 201 in the region between the ground plane 202 and the insert conductor 203 and proceeds outward. The concentric outgoing wave is reflected by the sides 207 and 208 and proceeds inwardly in the area between the insert conductor 203 and the RF array 206. The reflection from the edge of the circular periphery causes the waves to stay in the same phase (i.e., it is the same phase reflection). The advancing wave is slowed by the dielectric layer 205. At this point, the traveling wave begins to interact and stimulate the elements of the RF array 206 to obtain the desired scattering.

To terminate the traveling wave, a termination 209 is included in the antenna at the geometric center of the antenna. In one embodiment, the termination 209 includes a pin termination (e.g., a 50? Pin). In another embodiment, the termination 209 includes an RF absorber 219 that terminates unused energy to prevent reflection of its unused energy back through the feed structure of the antenna. These may be used at the top of the RF array 206.

Figure 2b shows another embodiment of an antenna system with outgoing waves. 2B, the two ground planes 210, 211 are substantially parallel to the dielectric layer 212 (e.g., a plastic layer, etc.) between the ground planes 210, 211. The RF absorbers 213 and 214 (e.g., resistors) couple the two ground planes 210 and 211 together. Coaxial pin 215 (e.g., 50 OMEGA) powers the antenna. The RF array 216 is on top of the dielectric layer 212.

In operation, the feeder wave is fed through the coaxial pin 215, traveling outward in a concentric fashion and interacting with elements of the RF array 216.

The cylindrical feeding of both antennas of Figs. 2A and 2B improves the service angle of the antenna. Instead of a service angle of plus or minus 40 degrees azimuth (± 45 ° Az) and plus or minus 25 degrees elevation (± 25 ° El), in one embodiment, the antenna system has bore sight in all directions, (75 degrees) to the service angle. As with any beam-forming antenna consisting of many individual radiators, the overall antenna gain depends on the gain of the angle-dependent components themselves. If a conventional radiating element is used, the overall antenna gain typically decreases as the beam is pointed out of sight further. At 75 degrees out of sight, a significant gain reduction of about 6 dB is expected.

Embodiments of antennas with cylindrical feeds solve one or more problems. They dramatically simplify the feed structure compared to antennas fed into a co-distributor network, thus reducing the overall required antenna and antenna feeder volume; Reducing sensitivity to manufacturing and control errors by maintaining high beam performance with coarse control (extending all methods to simple binary control); The cylindrical feed wave provides a more favorable side lobe pattern than the rectilinear feed because of the spatially diverse side lobes in the far field; Includes allowing the polarization to be dynamic, including allowing left-hand circular, right-hand circular, and linear polarization without the need for a polarizer.

Array of wave-scattering elements

The RF array 206 of FIG. 2A and the RF array 216 of FIG. 2B include a wave scattering subsystem that includes a group of patch antennas (i.e., scatterers) that act as emitters. This group of patch antennas includes an array of scattering metamaterial elements.

In one embodiment, each of the scattering elements of the antenna system is comprised of a lower conductor, a dielectric substrate, and an upper conductor, and a complementary electric inductive-capacitive resonator ("complementary electrical LC" or "CELC Quot;) and is part of the unit cell that is etched in the top conductor or deposited on the top conductor.

In one embodiment, a liquid crystal (LC) is injected into the gap around the scattering element. The liquid crystal is encapsulated in each unit cell and separates the lower conductor associated with the slot from the upper conductor associated with the patch. The liquid crystal has a permittivity which is a function of the orientation of molecules including the liquid crystal, and the orientation of the molecules (and thus the dielectric constant) can be controlled by adjusting the bias voltage across the liquid crystal. Using this characteristic, the liquid crystal acts as an on / off switch for transmission of energy from the wave guided to the CELC. When switched on, the CELC electronically emits electromagnetic waves like a small dipole antenna.

Controlling the thickness of the liquid crystal increases the beam switching speed. A reduction of fifty percent (50%) of the gap (thickness of the liquid crystal) between the bottom and top conductors causes a fourfold increase in speed. In another embodiment, the thickness of the liquid crystal causes a beam switching speed of approximately fourteen milliseconds (14 ms). In one embodiment, LC is doped in a manner well known in the art to improve responsiveness so that a seven millisecond (7 ms) request can be met.

The CELC element is parallel to the plane of the CELC element and responds to a magnetic field applied perpendicular to the CELC gap complement. When a voltage is applied to the liquid crystal in a metamaterial scattering unit cell, the magnetic field component of the guided wave in turn induces a magnetic excitation of the CELC that produces an electromagnetic wave of the same frequency as the guided wave.

The phase of the electromagnetic wave generated by a single CELC can be selected by the position of the CELC on the vector of the guided wave. Each cell generates a wave of the same phase as a guided wave parallel to the CELC. Because the CELC is smaller than the wavelength, the output wave has the same phase as the guided wave as it passes below the CELC.

In one embodiment, the cylindrical feed geometry of this antenna system allows the CELC elements to be placed at an angle of forty-five degrees (45 degrees) to the vector of wave-assisted waves. The position of this element enables control of the polarization of the free-space wave coming from, or received by, this element. In one embodiment, the CELC is arranged with inter-element spacing less than the free space wavelength of the operating frequency of the antenna. For example, if there are four scatter factors per wavelength, the element of the 30 GHz transmit antenna will be about 2.5 mm (ie 1/4 of a 10 mm free space wavelength at 30 GHz).

In one embodiment, the CELC is implemented with a patch antenna comprising a patch co-located on the front of the slot with the liquid crystal therebetween. In this regard, a metamaterial antenna acts like a slotted (scattering) waveguide. With a slotted waveguide, the phase of the output wave follows the position of the slot with respect to the guided wave.

Figure 3 shows a top view of one embodiment of a patch antenna or scattering element. 3, the patch antenna has a patch 301 that is collocated to face the front of the slot 302 having the liquid crystal LC 303 between the patch 301 and the slot 302.

Figure 4 shows a side view of a patch antenna that is part of a cyclically fed antenna system. 4, the patch antenna is on a dielectric 402 (e.g., a plastic insert, etc.) over the inset conductor 203 (or ground conductor as in the case of the antenna in Figure 2B) of Figure 2A.

The iris board 403 is a ground plane (conductor) having a plurality of slots, such as slots 403a, on the top of the dielectric 402 and on the front of the dielectric 402. The slot may be referred to herein as an iris. In one embodiment, the slot of the iris board 403 is created by etching. It should be noted that, in one embodiment, the highest density of slots or cells in which they are part is? / 2. In one embodiment, the density of the slot / cell is? / 3 (i.e., 3 cells per?). It should be noted that different densities of the cells may also be used.

A patch board 405 containing a number of patches, such as patches 405A, is positioned in front of an iris board 403 separated by an intermediate dielectric layer. Each of the patches, such as patch 405A, is co-located with one of the slots of the iris board 403. In one embodiment, the intermediate dielectric layer between the iris board 403 and the patch substrate 405 is a liquid crystal substrate layer 404. The liquid crystal acts as a dielectric layer between each patch and its co-located slot. It should be noted that a substrate layer other than LC may be used.

In one embodiment, the patch board 405 includes a printed circuit board (PCB), each patch comprising a metal on the PCB, where the metal around the patch is removed.

In one embodiment, the patch board 405 includes vias of each patch on the side of the patch board opposite the side opposite the slot where the patch is co-located. The vias are used to connect one or more traces to the patch to supply voltage to the patches. In one embodiment, a matrix drive is used to apply a voltage to the patch to control them. The voltage is used to tune, adjust, or detune individual elements to enable beam shaping.

In one embodiment, instead of using a circuit patch board, the patch is typically used for a liquid crystal display (LCD) such as a glass layer (e.g., typically Corning Eagle glass, for example) Glass). ≪ / RTI > Fig. 17 shows a portion of a cylindrical power feed antenna comprising a glass layer containing a patch. Fig. 17, the antenna includes an electrically conductive base or ground layer 1701, a dielectric layer 1702 (e.g., plastic), a slotted iris board 1703 (e.g., circuit board), a liquid crystal substrate Layer (LC layer) 1704, and a glass layer 1705 containing a patch 1710. [ In one embodiment, the patch 1710 has a rectangular shape. In one embodiment, the patches are the same for each row or column, while the orientation of the cavity-positioned slots is oriented identically for each other in rows or columns.

In one embodiment, a cap (e.g., a radome cap) covers the top of the patch antenna stack to provide protection.

6 shows an embodiment of the iris board 403. FIG. This is the underconductor of the CELC. Referring to FIG. 6, the iris board includes an array of slots. In one embodiment, each slot is arranged at either +45 or -45 relative to the colliding feed wave at the center position of the slot. In other words, the layout pattern of the scattering element (CELC) is arranged at +/- 45 degrees with respect to the vector of waves. Below each slot, which is essentially another slot, there is a circular opening 403B. The slot is at the top of the iris board, and the circular or elliptical opening is at the bottom of the iris board. It should be noted that these apertures, which may be about 0.001 "or 25 mm deep, are optional.

The slotted array is loaded with adjustable directionality. By adjusting the individual slots to either off or on, each slot is adjusted (i.e., adjusted to operate at a given frequency) to provide a predetermined scatter in the operating frequency of the antenna.

Figure 7 shows how the orientation of one iris (slot) / patch combination is determined. Referring to Fig. 7, the letter A represents a solid black arrow indicating the feeding vector from the cylindrical feed position to the center of the element. The letter B represents a dashed orthogonal line representing an axis perpendicular to "A ", the letter C represents a dashed rectangle encircling slot surrounded by a dotted line rotated by 45 degrees relative to" B " .

Fig. 8 shows an example of an iris grouped into two sets of a first set rotated by -45 degrees with respect to a power feed vector (feed pointing vector) and a second set rotated by +45 degrees with respect to the feed vector Slot). Referring to FIG. 8, group A includes slots with a rotation of -45 degrees for the feed vector, while group B includes slots with a rotation of + 45 degrees for the feed vector.

The designation of the global coordinate system is not important and thus the rotation of the negative angle and positive angle merely depicts the relative rotation of the elements relative to each other and to the feed direction It is important because. In order to generate circularly polarized light from two sets of linearly polarized elements, two sets of elements are perpendicular to each other and at the same time have the same amplitude excitation. If you rotate them +/- 45 degrees about the feed wave, you achieve all the desired features at once. Rotating one set by 0 degrees and the other by 90 degrees will achieve a vertical goal, but not the same amplitude excitation goal.

FIG. 9 illustrates one embodiment of a patch board 405. FIG. This is the top conductor of the CELC. Referring to FIG. 9, the patch board includes a rectangular patch covering the slot and completing a linearly polarized patch / slot resonant pair that is turned off and on. The pairs are turned on or off by applying a voltage to the patch using the controller. The voltage required is dependent on the liquid crystal mixture used, the threshold voltage that is introduced as a result of starting to regulate the liquid crystal, and (the higher the voltage ultimately degrading the circuit through the liquid Or does not produce any effect except shorting). In one embodiment, the matrix drive is used to apply a voltage to the patch to control the coupling.

Antenna system control

The control structure has two major components, the controller including the driving electronics for the antenna system being below the wave scattering structure, while the matrix-driven switching array has the radiation Which is scattered throughout the RF array. In one embodiment, the driving electronics for the antenna system is a commercial off-the-shelf (COTS) device used in commercial television appliances that adjusts the bias voltage for each scattering element by adjusting the amplitude of the AC bias signal to that element. The-Shelf) LCD control.

In one embodiment, the controller uses software control to control the electronic device. In one embodiment, the control of the polarization is part of the software control of the antenna and the polarization is preprogrammed to match the polarization of the signal from the satellite service with which the earth station communicates or pre-programmed to match the polarization of the satellite's receive antenna .

In one embodiment, the controller also includes a microprocessor that executes software. The control structure may also include a sensor (nominally including a GPS receiver, a three-axis compass and an accelerometer) to provide position and orientation information to the processor. The location and orientation information may be provided to the processor by the earth station and / or other system that may not be part of the antenna system.

More specifically, the controller controls which elements are turned off and their elements are turned on at the frequency of operation. The elements are selectively detuned for frequency operation by voltage application. The controller supplies an array of voltage signals to the RF radiation patch to generate a modulation or control pattern. The control pattern causes the elements to turn on or off. In one embodiment, the control pattern is such that elements that follow a single helix (LHCP or RHCP) are "on" and elements farther from the helix are "off" (ie, a binary modulation pattern) (square waves). In another embodiment, multistate control is used in which the various elements are turned on and off for varying levels that are closer to the sinusoidal control pattern, in contrast to square waves (i.e., sinusoidal gray shading modulation patterns). Some elements emit stronger than others, rather than emit some and not some. Variable radiation is accomplished by applying a particular voltage level that modulates the liquid crystal permittivity in varying amounts, thereby varying the elements to allow some elements to emit stronger than others.

The generation of beams focused by the meta-material array of elements can be explained by the phenomenon of constructive and destructive interference. When they meet in free space, if they have the same phase, the individual electromagnetic waves are reinforced (constructive interference), and when they are encountered in free space they are canceled out (destructive interference) if they are in opposite phases. When a slot of a slotted antenna is placed so that each successive slot is located at a different distance from the excitation point of the guided wave, the scattered wave from that element has a different phase than the scattered wave of the previous slot will be. If the slot is separated by a quarter wavelength of the guided wavelength, each slot will spread the wave by a quarter of a phase delay from the previous slot.

Using an array, multiple patterns of constructive and destructive interference that can be generated can be theoretically positioned in any direction plus or minus ninety degrees (90 degrees) from the collimation of the antenna array using the principle of holography . Thus, by controlling which metamaterial unit cell is turned on or off (e.g., by changing the pattern in which the cell is turned on and the cell is turned off), other patterns of constructive and destructive interference can be generated, The antenna can change the direction of the wave forward. The time required to turn the unit cells on and off indicates the rate at which the beam can be switched from one place to another.

The polarization and beam pointing angles are defined by a modulation pattern, or a control pattern that specifies which element is on or off. In other words, the frequency that points to the beam and polarizes it in the desired manner depends on the control pattern. Since the control pattern is programmable, the polarization can be programmed for the antenna system. The desired polarization state is circular or straight for most applications. The circularly polarized state is a state in which the helically polarized state shown in Figs. 16A and 16B, that is, the right-hand circular polarization (RHCP) and the left circularly polarized light (left) -hand circular polarization (LHCP). It should be noted that in order to obtain the same beam while switching the feed direction (e.g., from the ingoing feed to the outgoing feed), the orientation, or sense, or helical modulation pattern is reversed . It should be noted that the direction of the feed wave (e.g., center or edge feed) is also specified when a given spiral pattern of on and off elements initiates causing left or right circular polarization.

The control pattern for each beam may be stored in the controller or calculated on the fly, or some combination thereof. When the antenna control system determines where the antenna is located and where it is pointing, it determines where the target satellite is located relative to the aim of the antenna. The controller then commands the on and off patterns of the individual unit cells of the array corresponding to the preselected beam pattern for the position of the satellite within the visible range of the antenna.

In one embodiment, the antenna system generates one steerable beam for the uplink antenna and one steerable beam for the downlink antenna.

Fig. 10 shows an example of an element having a patch in Fig. 9 determined to be out of operation frequency, and Fig. 11 shows an example of an element with a patch in Fig. 9 determined to be at the frequency of operation. FIG. 12 shows the results of full wave modeling showing the electric field response to the on and off modulation patterns for the elements of FIGS. 10 and 11. FIG.

Figure 13 shows beamforming. Referring to FIG. 13, an interference pattern is used to identify an interference pattern corresponding to a selected beam pattern and then adjust the voltage across the scattering element to produce a beam along the principle of holography to provide an arbitrary antenna radiation pattern Lt; / RTI > The basic principles of holography, including the terms "object beam" and "reference beam ", which are usually used in connection with these principles, are well known. In the situation of forming a desired "object beam" using a wave going as "reference beam ", RF holography is performed as follows.

The modulation pattern is determined as follows. First, a reference wave (beam), sometimes referred to as a feed wave, is generated. 19A shows an example of a reference wave. 19A, the ring 1900 is the phase front of the electric and magnetic fields of the reference wave. They show a sinusoidal time variation. An arrow 1901 shows a radio wave propagating out of the reference wave.

In this example, the TEM or Transverse Electro-Magnetic wave proceeds in or out. The direction of propagation is also defined, and in this example the propagation outside the center feed point is selected. Planes of radio waves exist along the antenna surface.

Sometimes an object wave called a target beam is generated. In this example, the object wave is a TEM wave that travels in a direction 30 degrees off normal to the surface of the antenna having azimuth angle set to zero degrees. Polarization is also defined, in this example the right circularly polarized light is selected. 19B shows the generated object wave. 19B, the phase fronts 1903 of the electrical and magnetic fields of the propagating TEM wave 1904 are shown. Arrows 1905 are the electric field vectors at the top of each isotope in 90 degree increments. In this example, they adhere to the right circular polarization selection.

Interference or modulation pattern = Re {[A] x [B] ^* }

When the sinusoid is multiplied by the complex conjugate of the other sinusoid, the real part is taken and the resulting modulation pattern is also a sinusoid. Spatially, a modulation pattern is a site that emits a maximum or strong radiation when the maximum of the reference wave satisfies the maximum of the object wave (all of the time-varying quantities in a sine wave shape). In practice, this interference is calculated at each scattering location and depends not only on its position, but also on the polarization of the element based on its rotation and on the polarization of the object wave at the location of the element. 19C is an example of a sine wave modulation pattern resulting from the result.

It should be noted that further selection may be made to simplify the resulting sinusoidal gray shade modulation pattern into a square wave modulation pattern.

It should be noted that the voltage across the scattering element is controlled by adjusting the voltage applied between the patch and the ground plane, which is the metallization of the top of the iris board.

transform Example

In one embodiment, the patches and slots are arranged in a honeycomb pattern. Examples of such patterns are shown in Figs. 14A and 14B. Referring to Figs. 14A and 14B, the honeycomb structure is shifted by half an element interval to the left or right side in each row, or alternatively shifted upward or downward by half an element interval for each column.

In one embodiment, the patches and associated slots are arranged in a ring shape to create a radial layout. In this case, the slot center is disposed on the ring. 15A shows an example of the patches (and their co-located slots) disposed in the ring. Referring to FIG. 15A, the center of the patch and slot is on the ring and the ring is concentrically positioned with respect to the feed or termination point of the antenna array. Adjacent slots located in the same ring are oriented at approximately 90 degrees relative to each other (if evaluated at their centers). More specifically, they are oriented at the same angle as the angular displacement along the ring including the geometric center of the 90 degree positive (+) two elements.

Fig. 15B is an example of a control pattern for a ring-based slotted array as shown in Fig. 15A. The near field and far field resulting from the 30 ° beam pointed to by LHCP are shown in Figure 15c, respectively.

In one embodiment, the feed structure is shaped to control the coupling so that the emitted or scattered power is nearly constant across a complete 2D aperture. This is accomplished by using a linear taper of the dielectric, or similar taper in the case of a ridged feed network that causes fewer bonds near the feed point and many bonds far away from the feed point. The use of a linear taper up to the height of the feed, by containing a smaller volume of energy due to a greater proportion of the remaining energy of feed scattering from each element, results in a 1 / r attenuation of the traveling wave as it propagates away from the feed point neutralize decay. This is important to create a uniform amplitude excitation across the aperture. In the case of a non-radiating symmetrical feed structure, such as having a square or rectangular dimension, this tapering can be applied in a non-radially symmetrical manner so that the scattered power is nearly constant across the aperture. The complementary technique requires elements that are differently adjusted in the array based on how far they are from the feed point.

An example of a taper is implemented using a dielectric of a Maxwell fish-eye lens shape that produces a proportional increase in response to a radiation intensity to accommodate the 1 / r attenuation.

Figure 18 shows a linear taper of dielectric. 18, a tapered dielectric (not shown) having a coaxial feeder 1800 is provided to provide a concentric feed wave to perform elements of the RF array 1801 (patch / iris pair) ; 1802). The dielectric 1802 (e.g., plastic) is tapered from a highest height to a lower height near the coaxial feeder 1800 at a point farthest from the coaxial feeder 1800. For example, the height B is greater than the height A as it approaches the coaxial feeder 1800. [

According to this idea, in one embodiment, the dielectric is formed in a non-radially symmetric shape to concentrate the energy where necessary. For example, in the case of a square antenna fed from a single feed point as described herein, the path length from the center of the square to the corner is the length of the path from the center to the center of the square side of the square 1.4 times longer. Therefore, more energy should be concentrated toward the four corners than the four midpoints of the sides of the square, and the rate of energy scattering must also be different. Symmetrical shapes and other structures on the nonradiative principle of feeding can achieve these requirements.

In one embodiment, a dissimilar dielectric is stacked with a given feed structure to control the power scattered from the feed to the openings as the wave emits towards the outside. For example, when one or more heterogeneous dielectric media are stacked on top of each other, the electrical or magnetic energy intensity can be concentrated in a particular dielectric medium. One specific example uses a foam layer such as air with a total thickness less than lf / 2 at an operating frequency that results in a higher concentration of magnetic field energy in the plastic than a plastic layer and foam rubber such as air.

In one embodiment, for patch / iris detuning to control coupling through the aperture and scatter more or less energy along the direction of the feed and desired aperture excitation weighting (e.g., Lt; RTI ID = 0.0 > a < / RTI > fewer elements are turned on). For example, in one embodiment, an initially used control pattern turns on less slots than the remaining time. For example, initially only a certain percentage (e.g., 40%, 50%) of the elements (patch / iris slot pair) near the center of the cylindrical feed that is to be turned on to form the beam, And then the rest that is further from the cylindrical feed is turned on. In an alternate embodiment, the element can be continuously turned on from the cylindrical feed as the wave propagates further away from the feed. In another embodiment, the ridden feed network replaces the dielectric spacer (e. G., The plastic of the spacer 205) and allows for additional control of the orientation of the propagating feeder wave. The ridge can be used to generate a symmetrical propagation of the supply (i. E., The pointing vector is not parallel to the wave vector) to correspond to the 1 / r attenuation that can be used to create the feed asymmetric propagation. Thus, the use of ridges in the feed helps to direct energy to where it is needed. By directing more ridges and / or variable height ridges to the lower energy region, more uniform illumination is created at the openings. This allows a deviation from the purely radial feed configuration, since the direction of propagation of the feed wave may no longer be radially oriented. Slots through the ridge combine strongly, while slots between the ridge combine weakly. Thus, in accordance with the desired coupling (to obtain the desired light), the use of the ridge and the placement of the slots enable control of the coupling.

In yet another embodiment, a complex feed structure is used that provides circularly non-symmetrical aperture illumination. This application may be a non-uniformly illuminated square or generally non-circular aperture. In one embodiment, a non-radially symmetric dielectric is used that provides more energy to some areas than others. That is, the dielectric may have regions with different dielectric controls. There is an example of a dielectric distribution that looks like a Maxwell fish-eye lens. This lens provides different amounts of power to different parts of the array. In another embodiment, the ridge feed structure is used to deliver more energy to some areas than others.

In one embodiment, multiple cylindrically powered sub-aperture antennas of the type described herein are disposed. In one embodiment, one or more additional feed structures are used. Also, in one embodiment, distributed amplification points are included. For example, the antenna system may include multiple antennas as shown in FIG. 2A or 2B in the array. The array system may be 3x3 (9 total antennas), 4x4, 5x5, etc., but other configurations are possible. In this configuration, each antenna may have a separate feed. In another embodiment, the number of amplification points may be less than the number of power feeds.

Benefits and Benefits

Improved beam performance

One advantage to embodiments of the present invention architecture is better beam performance than linear feed. The natural built-in taper at the edge can help achieve good beam performance.

In the array factor calculation, the FCC mask can be met from a 40 cm aperture with only ON and OFF elements.

Due to the cylindrical feeding, embodiments of the present invention do not have an impedance swing near the broadside without bandgap created by the one-wave periodic structure.

Embodiments of the present invention are free of diffraction mode problems when scanning away from the broadside.

Dynamic polarization Dynamic Polarization)

There are (at least two) element designs that can be used in the architecture described here: circularly polarized elements and linearly polarized element pairs. Using a linearly polarized element pair, the circular polarization sense can be changed dynamically by phase delaying or advancing the modulation applied to one set of elements for the second. To achieve linear polarization, one set of phase advance for the second (physically orthogonal set) would be 180 degrees. Linear polarization can also be synthesized only with element patter changes, which provides a mechanism for tracking linear polarization.

Operating Bandwidth ( Operational Bandwidth)

The on-off mode of operation has the opportunity for extended dynamic and instantaneous bandwidth, since the mode of operation does not require each element to be adjusted to a specific part of its resonance curve. The antenna can operate continuously through both the amplitude and phase hologram portions of the range without sufficient performance impact. This places the motion range much closer to the overall adjustable range.

Possible smaller clearances with quartz / glass substrate

The cylindrical feed structure can utilize a TFT architecture that implies a function in quartz or glass. These substrates are much stiffer than circuit boards, and there is a better known technique to achieve a gap size around 3 um (micrometer, um) to achieve spacing. A gap size of 3 um will result in a 14 ms switching speed.

Complexity Reduction

It is disclosed that the architecture described herein requires only a single bonding stage without machining operations in production. This is combined with the switch in the TFT-driven electronics to eliminate costly materials and some tough requirements.

While many modifications and variations of this invention will become apparent to those skilled in the art after reading the foregoing detailed description, it should be understood that any specific embodiment shown and described by way of illustration is in no way intended to be considered limiting. You should understand. Accordingly, references to the details of the various embodiments are not intended to limit the scope of the claims, which only list those features that are regarded as essential to the invention by itself.

Claims (24)

An antenna feeding device for inputting a cylindrical feeding wave; And
A radio frequency (RF) tunable slotted array of a plurality of surface scattering antenna elements coupled to an antenna feeder,
The cylindrical feed wave propagates concentrically from the feeder toward the outside,
Wherein the cylindrical feed wave interacts with an RF array to generate a beam, the RF array having a plurality of slots, each of the plurality of slots having a predetermined Of the antenna.
delete 2. The antenna of claim 1, wherein each slot is adapted to operate at an operating frequency of the antenna.
4. The antenna of claim 3, wherein each slot of the plurality of slots includes a first set of slots in which the slotted array is rotated by +45 degrees with respect to the propagation direction of the cylindrical feed wave, 45 or -45 degrees with respect to a cylindrical feeder wave impinging at a central position of each slot, so as to include a second set of slots rotated at -45 degrees.
2. The apparatus of claim 1, wherein the slotted array comprises:
A plurality of slots; And
A plurality of patches,
Each patch is co-located across a plurality of slots, separated from one slot of the plurality of slots to form a patch / slot pair, and each patch / slot pair is turned on Off or on.
6. The antenna of claim 5, wherein each slot of the plurality of slots and a dielectric is present between the associated patches in the plurality of patches.
7. An antenna according to claim 6, wherein the dielectric comprises a liquid crystal.
The method according to claim 6,
Further comprising a controller for causing a beam to be generated by applying a control pattern for controlling which patch / slot pair is on and off.
9. The method of claim 8, wherein the control pattern is configured to turn on only a subset of the patch / slot pairs used to generate the beam during the first stage, And turns on the pair of slots.
6. The antenna according to claim 5, wherein a plurality of patches are arranged in a plurality of rings, and the plurality of rings are concentrically positioned with respect to the antenna feeding device of the slotted array.
The antenna according to claim 5, wherein a plurality of patches are included in the patch board.
The antenna according to claim 5, wherein a plurality of patches are included in the glass layer.
The antenna according to claim 1, further comprising a dielectric layer on which a cylindrical feeding wave proceeds.
14. The method of claim 13,
Ground plane;
Further comprising a coaxial pin coupled to a ground plane for inputting a feed wave to the antenna,
Wherein the dielectric layer is between the ground plane and the slotted array.
15. The method of claim 14,
Further comprising the at least one absorber coupled to the RF ground plane and slotted array to end the unused energy to prevent the reflection of the thin unused energy back to the antenna through an antenna as claimed.
15. The method of claim 14,
Insertion conductors;
A spacer between the inserting conductor and the ground plane; And
Further comprising a side region for coupling the ground plane to the slotted array,
Wherein the dielectric layer is between the insert conductor and the slotted array.
17. An antenna according to claim 16, wherein the side region has two sides, each of the two side regions being angled so that the feeder wave propagates from the spacer layer of the feed device to the dielectric layer of the feeder.
17. The antenna of claim 16, wherein the spacer comprises a foam.
14. The antenna of claim 13, wherein the dielectric layer comprises plastic.
14. The antenna of claim 13, wherein the dielectric layer is tapered.
14. The antenna of claim 13, wherein the dielectric layer comprises a plurality of regions having different dielectric constants.
14. The antenna of claim 13, wherein the dielectric layer comprises a plurality of distributed structures that affect the propagation of the feeder wave.
The antenna according to claim 1, further comprising a ridged feeding network in which a cylindrical feeding wave proceeds.
An antenna feeding device for inputting a cylindrical feeding wave;
A dielectric layer on which feeder waves propagate;
A plurality of slots oriented at a predetermined angle with respect to a propagation direction of a cylindrical power supply wave; And
A plurality of patches,
The cylindrical feed wave is propagated concentrically from the feeding device,
Wherein each patch is co-located across a plurality of slots and separated from one slot of the plurality of slots using a liquid crystal layer to form a patch / slot pair, each patch / The pair of patches / slots and the pairs of the pair of feed / discharge lines are connected to each other in order to generate a beam when the cylindrical feeder waves collide at a central position of the respective slots. Wherein the antenna is an antenna.

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