VARIABLE DIELECTRIC CONSTANT-BASED ANTENNA AND ARRAY

Abstract

An antenna and antenna array are provided. A radiating elements and corresponding feed lines are provided over a variable dielectric constant material sandwiched between two panels. The sandwich may be in the form of an LCD. The dielectric constant in a selected area under the conductive line can be varied to control the phase of the radiating element. The dielectric constant in a selected area under the radiating element can be varied to control the resonance frequency of the radiating element. The dielectric constant in a selected area under the conductive line can be varied to also control the polarization of the radiating element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, exemplify the embodiments of the present invention and, together with the description, serve to explain and illustrate principles of the invention. The drawings are intended to illustrate major features of the exemplary embodiments in a diagrammatic manner. The drawings are not intended to depict every feature of actual embodiments nor relative dimensions of the depicted elements, and are not drawn to scale.

FIG. 1 illustrates an example of a microstrip antenna of the prior art.

FIG. 2 illustrates a cross-section of an LCD of the prior art.

FIG. 3A depicts an example of a scanning antenna according to an embodiment of the invention, while FIG. 3B depicts a cross section of an enlarged area shown by the broken-line circle of FIG. 3A.

FIG. 3C illustrate a cross-section of an embodiment wherein the dielectric constant is controlled using an LCD.

FIG. 4 illustrates a single patch microstrip antenna with dual feed arranged to provide dual circular polarization.

FIG. 5 depicts a scanning array using corporate feed according to an embodiment of the invention.

FIG. 6 illustrates a scanning antenna array with serial feed according to an embodiment of the invention.

DETAILED DESCRIPTION

Various embodiments of the invention are generally directed to a structure of radiating elements and their feed lines provided over an LCD structure, and a scanning antenna array and systems incorporating such a structure. In the context of the description of the various embodiments, the LCD structure used for the inventive antenna need not include a lighting source. The various embodiments described herein may be used, for example, in connection with stationary and/or mobile platforms. Of course, the various antennas and techniques described herein may have other applications not specifically mentioned herein. Mobile applications may include, for example, mobile DBS or VSAT integrated into land, sea, or airborne vehicles. The various techniques may also be used for two-way communication and/or other receive-only applications.

FIG. 3A depicts an example of a scanning antenna according to an embodiment of the invention, while FIG. 3B depicts a cross section of an enlarged area shown by the broken-line oval of FIG. 3A. As shown in FIG. 3A, a microstrip array, comprising elements 305-320 is provided over dielectric 330. Lines 305′-320′ lead to the main line 340, which is coupled to the source 345. As shown in FIG. 3B, the dielectric 330 is provided over a variable dielectric material 350, such as liquid crystal, which is sandwiched by a back panel 355, which may be glass. Using this configuration, the microstrip array can be used as a scanning antenna array. That is, by separately changing the dielectric constant of the material 350 under each of the feed line 305′-320′, as shown by the broken-line rectangle, a phase delay can be introduced between the radiation of the array elements 305-320.

More specifically, the phase, Φ, can be expressed as:

Φ=2πd/λ_g

wherein λ_g is the wavelength in the matter and d is the length of the propagation line. On the other hand, λ_g can be expressed as:

λ_g=λ₀/√ε_eff

wherein λ₀ is the wavelength in air, ε_eff is a function of ε_r, line width, and other physical parameters of the microstrip line, and ε_r is the dielectric constant of the propagation material. Then the phase can be expressed as:

Φ=2πd√ε_r/λ₀

Therefore, by separately controlling the dielectric constant of a section of the variable dielectric material 350 under each of the conductive line 320, the phase of each radiating element can be changed. Also, the phase can also be controlled by the length, d, of the section of the variable dielectric material 350 that is controlled.

FIG. 3C illustrate a cross-section of an embodiment wherein the dielectric constant is controlled using an LCD. In FIG. 3C, radiating element 320 and conductive line 302′ are provided over insulating layer 330, which may be a glass panel. The insulating layer 330 is provided over an LCD comprising transparent electrodes 325, upper dielectric plate 330′, liquid crystal 350, lower dielectric plate 355, and lower electrode 360. The liquid crystal may be provided in zones, as illustrated by the broken lines, and the zones may correspond to the electrodes 325. The lower electrode 360 is coupled to common potential, e.g., ground. The transparent electrodes 325 can be individually coupled to a potential 390. When the potential on any of the transparent electrodes 325 changes, the dielectric constant of the liquid crystal below it changes, thereby inducing a phase change in conductive line 320′. The phase change can be controlled by choosing the amount of voltage applied to the transparent electrode 325, i.e., controlling ε_r, and also by controlling the number of electrodes the voltage is applied to, i.e., controlling d.

To illustrate, the following calculations are made to find the relationship enabling a phase shift of 2π. When the conductive line is partially over a partially or non-biased electrode, so that the effective dielectric constant is ε₁, and partially over a biased electrode creating dielectric constant ε₂, the following results:

2πd√ε₁/λ₀−2πd/ε₂/λ₀=2π

this simplifies to:

√ε₁−√ε₂=λ₀/d

Therefore, by controlling the amount of bias, the length of the biased material, or both, one can achieve any phase shift necessary. Since in a commercial LCD the number of pixels biased and the amount of bias can be controlled independently, one may easily construct a scanning array according to this invention and easily control both ε_r and d.

It should be noted that the invention is not limited to the use of an LCD. That is, any material that exhibits a controllable variable dielectric constant can be used. For example, any ferroelectric material may be used instead of the liquid crystal. The embodiment shown here uses LCD, as the LCD technology is mature and readily available, which makes the invention very attractive and easy to implement.

Another feature of the invention is variable frequency scanning array. That is, as shown in the embodiments of FIG. 3A-3C, the entire area under the array has a controllable variable dielectric constant. By changing the dielectric constant under the conductive lines, one obtain phase shift, which provides the scanning of the array. On the other hand, one can also change the dielectric constant under each antenna patch. By changing the dielectric constant under the antenna patch, the resonant frequency of the patch changes. If one uses an LCD or similar arrangement, one would be able to control the amount of change of the dielectric constant under the patch by selecting the appropriate potential applied to the electrodes under the patch, thereby controlling the variability of the operating frequency of the patch. Similarly, one may also control the size of the area under the patch that is being biased, to thereby control the resonance frequency of the array to provide a frequency tunable antenna or array.

Yet another feature of the inventive antenna is the simplicity by which circular polarization and dual circular polarization can be implemented. FIG. 4 illustrates a single patch microstrip antenna 405 formed over a variable dielectric constant sandwich as explained above, such as, e.g., an LCD. The patch is fed from two sides by two conductor lines 405′ and 405″. An area under each of the conductor lines, illustrated by the broken-line rectangles, may be controlled to vary the dielectric constant so as to cause a 90° phase shift. By selecting which area is phase shifted, the patch can be left-hand or right-hand circularly polarized. Of course, since the dielectric constant may be changed at will, the selection of RHCP or LHCP can be changed at any time. Notably, the LHCP and RHCP can be accomplished while feeding from a single point. This is an advantage over the prior art wherein for such a feature a hybrid feed must be provided and wherein the feeding point must be changed in order to change between LHCP and RHCP. Here, on the other hand, the feed is fixed and is provided from a single point, thereby eliminating the complexity associated with a hybrid feed.

The inventive scanning antenna array can be made in various radiating and feeding configurations to provide various scanning characteristics, various frequency tuning, and various polarizations, to fit many applications. To illustrate, the following are examples of corporate and serial feeding utilizing the inventive features of the invention.

FIG. 5 depicts a scanning array using corporate feed according to an embodiment of the invention. In FIG. 5, four antenna patches 505-520 are provided over a variable dielectric sandwich, such as an LCD. Each patch has an associated conductive line 505′-520′ which traverses an area of controllable variable dielectric constant, indicated by a respective broken-line rectangle. All of the associated conductive lines 505′-520′ are coupled to a main feed line 540, which is coupled to the feed point 545. As can be understood by those skilled in the art, by controllably varying the dielectric constant under each conductive line 505′-520′, the phase at each patch 505-520 may be varied, so as to generate a scanning array, in this particular case, a linear scanning array. However, this example can be easily generalized to any configuration with any number of patches to generate linear or 2-dimensional scanning array.

FIG. 6 illustrates a scanning antenna array with serial feed according to an embodiment of the invention. In the example of FIG. 6, nine antenna patches 605-645 are used in a 2-dimensional array configuration. All the patches 605-645 are coupled together via conductive lines, wherein each conductive line traverses an area of controllably variable dielectric constant, illustrated by the broken-line rectangles. In this manner the phase for each patch can be varied controllably, so as to provide a 2-dimensional scanning array. As with the example of FIG. 5, this concept can be generalized to any other configuration with any number of patches.

Finally, it should be understood that processes and techniques described herein are not inherently related to any particular apparatus and may be implemented by any suitable combination of components. Further, various types of general purpose devices may be used in accordance with the teachings described herein. It may also prove advantageous to construct specialized apparatus to perform the method steps described herein. The present invention has been described in relation to particular examples, which are intended in all respects to be illustrative rather than restrictive. Those skilled in the art will appreciate that many different combinations of hardware, software, and firmware will be suitable for practicing the present invention. For example, the described software may be implemented in a wide variety of programming or scripting languages, such as Assembler, C/C++, per, shell, PHP, Java, HFSS, CST, EEKO, etc.

The present invention has been described in relation to particular examples, which are intended in all respects to be illustrative rather than restrictive. Those skilled in the art will appreciate that many different combinations of hardware, software, and firmware will be suitable for practicing the present invention. Moreover, other implementations of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

1. An antenna comprising: a back panel having a conductive layer provided on a surface thereof;a top panel;a variable dielectric constant material sandwiched between the back panel and the top panel;at least one radiating element provided over the top panel; and,at least one conductive line provided over the top panel and coupled to the at least one radiating element.

2. The antenna of claim 1, wherein the variable dielectric constant material comprises liquid crystal.

3. The antenna of claim 2, wherein the back panel and the top panel comprise an insulating material.

4. The antenna of claim 3, further comprising: at least one electrode provided on the top panel;an insulating layer provided over the electrode; and,wherein the at least one radiating element and the at least one conductive line are provided over the insulating layer.

5. The antenna of claim 4, wherein the variable dielectric constant material is provided in defined zones.

6. The antenna of claim 5, wherein the common electrode, back panel, liquid crystal, top panel and electrode comprise a liquid crystal display.

7. The antenna of claim 4, further comprising a power source coupled to the at least one electrode.

8. A scanning antenna array, comprising: a back panel;a top panel;a plurality of zones of variable dielectric constant material sandwiched between the back panel and the top panel;a plurality of radiating elements provided over the top panel;a plurality of conductive line provided over the top panel and each coupled to a respective one of the plurality of radiating elements, each of the conductive lines traversing over at least one of the zones.

9. The antenna of claim 8, wherein each of the zones further comprises an electrode.

10. The antenna of claim 9, further comprising an insulating layer provided over the electrodes, and wherein the radiating elements and the conductive lines are provided over the insulating layer.

11. The antenna of claim 8, wherein the dielectric constant of at least one of the zones is made to differ from the dielectric constant of at least one other zone.

12. The antenna of claim 9, wherein each of the electrodes is coupled to a power source.

13. A method of manufacturing an antenna, comprising: providing a back panel;providing a top panel;sandwiching a variable dielectric constant material between the back panel and the top panel;providing at least one radiating element over the top panel;providing at least one conductive line over the top panel and coupling the conductive line to the radiating element.

14. The method of manufacturing antenna of claim 13, wherein the step of sandwiching comprises sandwiching the variable dielectric constant in a plurality of zones.

15. The method of claim 15, further comprising: providing a plurality of electrode, each electrode provided over a respective one of the zones;providing a dielectric layer between the electrodes and the at least one radiating element and the conductive line.

16. The method of claim 13, wherein the step of sandwiching a variable dielectric constant material comprises sandwiching a liquid crystal in a plurality of zones.

17. The method of claim 13, wherein the steps of providing a back panel, providing a top panel, and sandwiching a variable dielectric constant material between the back panel and the top panel, comprises providing a liquid crystal display.

18. An antenna manufactured by the process comprising: providing a back panel;providing a top panel;sandwiching a variable dielectric constant material between the back panel and the top panel;providing at least one radiating element over the top panel;

19. The antenna of claim 18, wherein the process of manufacture further comprises: sandwiching the variable dielectric constant material in a plurality of zones, wherein at least one zone is provided under each of the at least one conductive line.

20. The antenna of claim 19, wherein the process of manufacture further comprises: providing a plurality of electrode, each electrode provided over a respective one of the zones;providing a dielectric layer between the electrodes and the at least one radiating element and the at least one conductive line.