Layer arrangement and method for testing a plurality of tunable radio frequency transmission elements

Abstract

A layer arrangement for a phased array antenna comprises phase shifting units arranged between stacked dielectric layers with a tunable dielectric material sandwiched in-between. Each phase shifting unit comprises a transmission line with phase shifting capabilities that is electrically connected with bias lines to a biasing circuit. A dielectric layer is made from an optically transparent material. An overlapping section of the bias lines of each of the phase shifting units is made from an optically transparent and electroconductive material. The tunable dielectric material affects the transmission or reflection of light that illuminates the tunable dielectric material depending on the respective tuning state. Testing this layer arrangement comprises illuminating the layer arrangement by light while a predetermined electric bias potential is applied to at least some of the phase shifting units, and during which the light emission from the layer arrangement is detected and compared with an expected light emission.

Claims

1. A method for testing a plurality of tunable radio frequency transmission elements (4) that are integrated into a layer arrangement (1), wherein the layer arrangement (1) comprises the tunable radio frequency transmission elements (4) arranged on or between at least two stacked dielectric layers (5, 6), wherein a layer of tunable dielectric material (12) is sandwiched between the at least two stacked dielectric layers (5, 6), wherein each tunable radio frequency transmission element (4) comprises at least one transmission line (3) with tunable capabilities that is electrically conductively connected with bias lines (10, 11) to a biasing circuit, wherein at least one of the at least two stacked dielectric layers (5, 6) is made from an optically transparent material, wherein at least an overlapping section of the bias lines (10, 11) of each of the tunable radio frequency transmission elements (4) is made from an optically transparent and electroconductive material, and wherein the tunable dielectric material (12) is selected from a group of materials that affect transmission or reflection of light that illuminates the tunable dielectric material (12) depending on a respective tuning state of the tunable dielectric material, the method comprising: a testing step during which the layer arrangement (1) is illuminated by light, during which a predetermined electric bias potential is applied to at least some of the tunable radio frequency transmission elements (4), and during which a light emission from the layer arrangement (1) depending on the predetermined electric bias potential is detected, and wherein the detected light emission is compared with a light emission that is expected for bias lines (10, 11) in proper working conditions.

2. The method according to claim 1, wherein the light emission is detected by a digital camera or an optical scanner.

3. The method according to claim 1, wherein all of the at least two stacked dielectric layers (5, 6) are made from an optically transparent material, and wherein during the testing step the layer arrangement (1) is illuminated from a first side of the layer arrangement (1) and light transmitted through the layer arrangement (1) is detected at a second side of the layer arrangement (1) that is opposing the first side.

4. The method according to claim 1, wherein during the testing step an identical bias potential is applied to the at least some of the tunable radio frequency transmission elements (4).

5. The method according to claim 1, wherein an intensity of the detected light emission is measured.

6. The method according to claim 1, wherein during the testing step the predetermined electric bias potential is applied to the at least some of the tunable radio frequency transmission elements (4) at the same time.

7. The method according to claim 1, wherein during the testing step the predetermined electric bias potential is applied to the at least some of the tunable radio frequency transmission elements (4) in a predetermined sequence one after another.

8. The method according to claim 1, wherein during the testing step a time difference between an application of a variation of the predetermined electric bias potential to a tunable radio frequency transmission element (4) and a resulting variation of the light emission is detected.

9. The method according to claim 1, wherein at least a section of the transmission line (3) of at least some of the tunable radio frequency transmission elements (4) is made from an optically transparent material, and wherein during the testing step the light emission from this section of the transmission line (3) of at least some of the tunable radio frequency transmission elements (4) is detected.

10. A layer arrangement (1) for use within a phased array antenna, wherein the layer arrangement (1) comprises a plurality of tunable radio frequency transmission elements (4) that are arranged on or between at least two stacked dielectric layers (5, 6), wherein a layer of tunable dielectric material (12) is sandwiched between the at least two stacked dielectric layers (5, 6), wherein each tunable radio frequency transmission element (4) comprises at least one transmission line (3) with tunable capabilities that is electrically conductively connected with bias lines (10, 11) to at least one biasing circuit, wherein at least one of the at least two stacked dielectric layers (5, 6) is made from an optically transparent material, wherein at least an overlapping section of the bias lines (10, 11) of each of the tunable radio frequency transmission elements (4) is made from an optically transparent and electroconductive material, and wherein the tunable dielectric material (12) is selected from a group of materials that affect the transmission or reflection of light that illuminates the tunable dielectric material (12) depending on a respective tuning state of the tunable dielectric material (12).

11. The layer arrangement (1) according to claim 10, wherein the overlapping section of the bias lines (10, 11) of each of the tunable radio frequency transmission elements (4) comprise a testing area (13) with a width of the testing area (13) larger than a width of the bias lines (10, 11) outside of the testing area (13).

12. The layer arrangement (1) according to claim 10, wherein at least a section of the transmission line (3) is made from an optically transparent material.

13. The layer arrangement (1) according to claim 10, wherein the tunable radio frequency transmission elements (4) are phase shifting units or comprise one or more phase shifting units.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 illustrates a schematic top view of a layer arrangement with phase shifting units that are arranged on or between at least two stacked dielectric layers with a layer of tunable dielectric material sandwiched between the at least two stacked dielectric layers, with each phase shifting unit comprising at least one transmission line with phase shifting capabilities that is electrically conductively connected with bias lines to at least one biasing circuit.

[0035] FIG. 2 illustrates a sectional view of a bias line of a phase shifting unit along the line II-II in FIG. 1 together with a schematic representation of an illumination device and an optical recording device used for performing the testing method.

[0036] FIG. 3 illustrates a schematic representation of the optical properties detected during the testing method of several bias lines which are in proper working condition.

[0037] FIG. 4 illustrates a schematic representation of the optical properties detected during the testing method of several bias lines, whereby an identical bias voltage has been applied to all bias lines, but two bias lines show deviating optical properties indicating a malfunctioning of said two bias lines.

[0038] FIG. 5 illustrates a schematic representation of the optical properties detected during the testing method of several bias lines, whereby a sequence of alternating bias voltages is applied to adjacent bias lines, but two bias lines show deviating optical properties indicating a malfunctioning of said two bias lines.

DETAILED DESCRIPTION

[0039] FIG. 1 illustrates a top view on a layer arrangement 1, and FIG. 2 illustrates a sectional view of a small region of the layer arrangement 1 shown in FIG. 1, whereby the small region shown in FIG. 2 is limited to a cross-section of a single bias line 2 that connects a transmission line 3 of a phase shifting unit 4. The layer arrangement 1 comprises two stacked dielectric layers 5, 6 made of glass or of another optically transparent dielectric material. The two dielectric layers 5, 6 are arranged parallel and at a distance towards each other. Each dielectric layer 5, 6 comprises a surface 7, 8 that is facing the surface 8, 7 of the other dielectric layer 6, 5, and both surfaces 7, 8 limit a volume 9 in between the two dielectric layers 5, 6. Two overlapping sections of two bias lines 10, 11 are arranged at the two surfaces 7, 8 facing towards each other. The overlapping sections of the two bias lines 10, 11 are made of an electrically conducting, but optically transparent material like e.g. indium tin oxide.

[0040] The volume 9 in between the two stacked dielectric layers 5, 6 is filled with a tunable dielectric material 12, which can be e.g. a tunable liquid crystal material with dielectric properties that depend on an electrical field that is applied to the tunable liquid crystal material. By changing the magnitude of the electrical field, the dielectric and optical properties of the tunable liquid crystal material can be affected and varied. In FIG. 2, the alignment of molecules of the tunable dielectric material 12 is predetermined by an electrical field that is created by application of a bias voltage between the two bias lines 10, 11, resulting in a predominantly random alignment of the molecules outside of a region between the overlapping sections of the two bias lines 10, 11, and further resulting in a predominantly unified alignment of the molecules within the region between the overlapping sections of the two bias lines 10, 11.

[0041] The two bias lines 10, 11 shown in FIG. 1 comprise a testing area 13 with a width of the testing area 13 larger than the width of the bias lines 10, 11 outside of the testing area 13. The sectional view of FIG. 2 shows a cross-section of the testing area 13 of the bias lines 10, 11 that are connected to the transmission line 3 of a phase shifting unit 4. In FIG. 1, a small region of a layer arrangement 1 of a phased array antenna comprising only five phase shifting units 4 is shown, whereby the phased array antenna comprises several thousand phase shifting units 4.

[0042] During the execution of the testing method, an illumination device 14 is arranged at one side of the layer arrangement 1, which is shown in FIG. 1 as being below the layer arrangement 1. At another side of the layer arrangement 1 opposite to the illumination device 14, there is an optical image recording device 15 that is capable of recording an image of the light emission from the layer arrangement 1, i.e. of the light that is emitted from the illumination device 14 and transmitted through the layer arrangement 1. For a qualitative verification of the working condition of the layer arrangement 1, a testing person can visually inspect the light emission from the layer arrangement 1 during the execution of the testing method. For a more elaborated and quantitative verification of the working condition of the layer arrangement 1, the optical image recording device 15 can be a digital camera or a charge-coupled device that allows for a precise measurement of spatial distribution of light intensity.

[0043] The testing method comprises a testing step, during which a predetermined electric bias potential is applied to the bias lines 10, 11 of the phase shifting units 4, and the light emission from the layer arrangement 1 is detected with the optical image recording device 15. Thus, if the predetermined electric bias potential is simultaneously applied to many or all of the phase shifting units 4, and if the light emission of many or all of the phase shifting units 4 is simultaneously detected and evaluated, it is possible to test and to verify the proper working condition of many or all of the phase shifting units within a single moment and at the same time.

[0044] FIG. 3 shows an image of the light emission of eight testing areas 13 of overlapping bias lines 10, 11 arranged along a line parallel to a border 16 of the layer arrangement 1. In order to test the working condition of the bias lines 10, 11, an identical bias voltage is applied to all of the testing areas 13. The image of the light emission of all testing areas 13 show eight regions with identical light emission, i.e. with equal size and intensity of light emission, whereby each region of light emission within the image is related to the corresponding testing area 13. Thus, all bias lines 10, 11 are functioning and in proper working condition.

[0045] FIG. 4 shows an image of the light emission of another eight testing areas 13 of overlapping bias lines 10, 11 arranged next to the bias lines 10, 11 shown in FIG. 3. In this FIG. 3, the light emission of the third testing area 17 and the fifth testing area 18 when counted from the left side deviates from the light emission of all other testing areas 13 of the bias lines 10, 11, indicating a defect or impairment of the respective third and fifth bias lines 10, 11 that results in improper working conditions of the respective phase shifting units 4.

[0046] FIG. 5 shows an image of the light emission of another eight testing areas 13 of overlapping bias lines 10, 11 also arranged along the border 16 of the layer arrangement 1. In order to measure a time dependent response time of the bias lines 10, 11 to changing bias voltages that are applied to the respective bias lines 10, 11, a sequence of alternating bias voltages is applied to the testing areas 13, whereby always the next but one testing area 13 is subjected to a large bias voltage, and each adjacent testing area 13 is simultaneously subjected to a zero bias voltage. Thus, always the next but one testing area 13 should show a bright light emission, whereas each adjacent testing area 13 should be relatively dark within the recorded image of the light emission of the layer arrangement 1. However, as can be seen in FIG. 5, the sixth testing area 19 and the eighth testing area 20 when counted from the left side deviate from the light emission of all other testing areas 13 of the bias lines 10, 11, each indicating a defect or impairment, even though the intensity of the light emission recorded for the sixth testing region 19 is identical to the two adjacent testing regions 13, but should be zero due to the alternating setting of the bias voltages.

[0047] While the present invention has been described with reference to exemplary embodiments, it will be readily apparent to those skilled in the art that the invention is not limited to the disclosed or illustrated embodiments but, on the contrary, is intended to cover numerous other modifications, substitutions, variations and broad equivalent arrangements that are included within the spirit and scope of the following claims.

[0048] The words “example” and “exemplary” as used herein mean serving as an instance or illustration. Any embodiment or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word example or exemplary is intended to present concepts in a concrete fashion.

[0049] As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, “A or B” refers to any of “A alone,” “B alone,” and “both A and B” unless specified otherwise or clear from context.

[0050] The articles “a” and “an” as used in this application including the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form.