System and method for calibrating radio frequency test chambers

Abstract

A system for calibrating radio frequency test chambers is provided. The system comprises an antenna array with a plurality of antenna elements arranged in a three dimensional configuration, a plurality of power measuring units downstream to the plurality of antenna elements and a processing unit. In this context, the plurality of power measuring units output a power from each antenna elements corresponds to a radiation pattern generated by an incident test signal. The processing unit is configured to analyze the power distribution of the test signal in order to calculate a calibration.

Claims

1. A system for calibrating radio frequency test chambers comprising: an antenna array with a plurality of antenna elements arranged in a three-dimensional configuration, a plurality of power measuring units configured downstream to the plurality of antenna elements, and a processing unit, wherein each of the plurality of power measuring units measures a power from each of the antenna elements corresponding to a radiation pattern generated by an incident test signal, wherein the processing unit is configured to analyze the power distribution of the test signal in order to calculate a calibration, and wherein the antenna array is dynamically expandable along at least one direction.

2. The system according to claim 1, wherein the directivity and the incident angle of the test signal are predetermined and wherein the test signal is generated from one or more test antennas.

3. The system according to claim 1, wherein the antenna array is adapted to receive each signal path corresponding to the one or more test antennas.

4. The system according to claim 1, wherein the processing unit is further configured to quantify a time variance in the measured output powers simultaneously measured at the plurality of antenna elements.

5. The system according to claim 1, wherein the antenna array is a patch antenna array with main radiation direction in three dimensions, and wherein the antenna array is situated in a fixed location within a radio frequency test chamber.

6. The system according to claim 1, wherein the antenna array creates a three-dimensional enclosure and wherein the plurality of power measuring units is confined within the enclosure.

7. The system according to claim 1, wherein the system further comprises a control unit adapted to orient at least one of the plurality of antenna elements in order to align the maximum gain of the antenna array in the incident direction of the test signal.

8. The system according to claim 1, wherein the system further comprises a switch matrix connecting the plurality of power measuring units to the processing unit, and wherein the switch matrix is adapted to input the measured power from each of the plurality of antenna elements to the processing unit.

9. The system according to claim 1, wherein the system further comprises a memory in order to store the measured powers and the calibration.

10. A method for calibrating radio frequency test chambers using an antenna array with a plurality of antenna elements arranged in a three-dimensional configuration comprising the steps of: measuring a power from each of the antenna elements corresponding to a radiation pattern generated by an incident test signal, and analyzing the power distribution of the test signal in order to calculate a calibration, wherein the antenna array is dynamically expandable along at least one direction.

11. The method according to claim 10, wherein the method further comprises the step of generating the test signal from one or more test antennas with a predetermined directivity and incident angle.

12. The method according to claim 10, wherein the method further comprises the step of receiving each signal path corresponding to the one or more test antennas.

13. The method according to claim 10, wherein the method further comprises the step of quantifying a time variance in the measured output powers simultaneously measured at the plurality of antenna elements.

14. The method according to claim 10, wherein the method further comprises the step of orienting at least one of the plurality of antenna elements in order to align the maximum gain of the antenna array in the incident direction of the test signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the invention are now further explained with respect to the drawings by way of example only, and not for limitation. In the drawings:

(2) FIG. 1 shows a block diagram of the system according to the first aspect of the invention,

(3) FIG. 2 shows a block diagram of the system performing calibration of a radio frequency chamber according to the first aspect of the invention by way of example only,

(4) FIG. 3a shows a first exemplary embodiment of the antenna array extension scheme according to the first aspect of the invention,

(5) FIG. 3b shows a second exemplary embodiment of the antenna array extension scheme according to the first aspect of the invention, and

(6) FIG. 4 shows a flow chart of an exemplary embodiment of the second aspect of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(7) Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings. However, the following embodiments of the present invention may be variously modified and the range of the present invention is not limited by the following embodiments.

(8) In FIG. 1, a block diagram of the system 1 according to the first aspect of the invention is illustrated. The system 1 comprises an antenna array 10 with a plurality of antenna elements 11.sub.1, 11.sub.2, . . . , 11.sub.N that are arranged in a three dimensional configuration and creates a three dimensional enclosure. The system 1 further comprises a plurality of power measuring units 12.sub.1, 12.sub.2, . . . , 12.sub.N downstream to the plurality of antenna elements and are confined within the three dimensional enclosure. The antenna array 10 receives signal paths from a test signal (not shown) and the power measuring units 12.sub.1, 12.sub.2, . . . , 12.sub.N sense a power from each antenna elements 11.sub.1, 11.sub.2, . . . , 11.sub.N corresponding to a radiation pattern that is generated by the test signal. A processing unit 13 determines antenna elements 11.sub.1, 11.sub.2, . . . , 11.sub.N with highest power to identify the incident direction of the test signal and further analyzes the power distribution of the test signal in order to calculate a calibration result.

(9) The system 1 further comprises a switch matrix 17 connected in-between the antenna array 10 and the processing unit 13 connecting each of the power measuring units 12.sub.1, 12.sub.2, . . . , 12.sub.N to a signal bus and inputs the measured power form the antenna elements 11.sub.1, 11.sub.2, . . . , 11.sub.N to the processing unit 13. Ideally, the switch matrix 17 is adapted to switch power values of the radio frequency signals in the form of analog and/or digital values. The switch matrix 17 may comprise additional signal conditioning means such as attenuators, filters, directional couplers and so on. The operation of said signal conditioning means are known in the art and therefore is not herein described in greater details.

(10) The processing unit 13 is connected to a memory 19 and a control unit 15. The control unit 15 is connected to the switch matrix 17 to control the switching operation and is further connected to the antenna array 10 to orient the antenna elements 11.sub.1, 11.sub.2, . . . , 11.sub.N in order to align the maximum gain of the antenna array 10 in the incident direction of the test signal.

(11) It is to be noted, that the plurality of antenna elements 11.sub.1, 11.sub.2, . . . , 11.sub.N and the plurality of power measuring units 12.sub.1, 12.sub.2, . . . , 12.sub.N are also collectively referred to as the antenna array 10. Furthermore, the processing unit 13, the control unit 15, the switch matrix 17 and the memory 19 are collectively referred to as tester 20 in general.

(12) In FIG. 2, a block diagram of the system 1 performing calibration of a radio frequency chamber 30 according to the first aspect of the invention is illustrated by way of example only. A test signal is generated from a signal generator 23 through two test antennas 21, 22 in the radio frequency test chamber 30. A user may align the test antennas 21, 22 as desired and specify the location where the potential device under test (DUT) antennas will be located. The antenna array 10 is fixed on the test location and acts as a reference antenna to facilitate path loss calibration. The spatial arrangement of the antenna elements 11.sub.1, 11.sub.2, . . . , 11.sub.N on the antenna array 10 is simulated as the potential DUT antennas and the power measuring units 12.sub.1, 12.sub.2, . . . , 12.sub.N reports the power of each path at the defined receive location with the defined incident angle. The measured power outputs are fed to the tester 20 where the tester 20 further analyzes the power distribution of the test signal to calculate a calibration result. Consequently, path loss calibration is performed simultaneously for each path of the test signal at arbitrary locations where the DUT antennas will be tested.

(13) In FIG. 3a, a first exemplary embodiment of the antenna array 40 extension scheme according to the first aspect of the invention is illustrated. The cuboid antenna array 40 comprises there array sections 40.sub.1, 40.sub.2 and 40.sub.3. It is to be noted that each array sections 40.sub.1,40.sub.2,40.sub.3 corresponds to the antenna array 10 comprising the antenna elements 11.sub.1, 11.sub.2, . . . , 11.sub.N and the power measuring units 12.sub.1, 12.sub.2, . . . , 12.sub.N. The consecutive sections are separated by cascading planes 45.sub.1,45.sub.2. The control unit 15 generates a control signal in order to activate the array sections 40.sub.1,40.sub.2,40.sub.3 and thereby connecting the array sections 40.sub.1,40.sub.2,40.sub.3 in series on the cascading planes 45.sub.1,45.sub.2 along the extension axis X. The array sections 40.sub.1,40.sub.2,40.sub.3 can be activated one after another or simultaneously. The total number of array sections 40.sub.1,40.sub.2,40.sub.3 is not limited to three, the number of array sections 40.sub.1,40.sub.2,40.sub.3 can be more or less depending on the size of the radio frequency chamber 30 as well as on the spatial arrangement of the potential DUT antennas. Furthermore, the shape of the antenna array 40 as well as the array sections 40.sub.1,40.sub.2,40.sub.3 are not limited to cuboid only. Any other shape, for instance, cubic, spherical and so on, also falls within the scope of the invention.

(14) In FIG. 3b, a second exemplary embodiment of the antenna array 50 extension scheme according to the first aspect of the invention is illustrated. The antenna array 50 is arranged in a box within a box formation where an inner array segment 54 is partially confined within an outer array segment 52. The inner array segment 54 is adapted to move along the extension axis X. The lateral displacement of the inner array segment 54 results in an extended array segment 56 with a lateral deflection of L. The control unit 15 controls the movement of the inner array segment 54, preferably by means of servomechanism and extends the antenna array 50 corresponding to the potential DUT and/or as desired. Although, a rectangular shape is illustrated for the antenna array 50, it is possible to implement other shapes, for instance cylindrical shape, convenient to construct the three dimensional antenna array 50. In contrast to the extension scheme illustrated in FIG. 3a, the antenna elements 11.sub.1, 11.sub.2, . . . , 11.sub.N and the power measuring units 12.sub.1, 12.sub.2, . . . , 12.sub.N of the array segments 52, 54, 56 remain active whether they are confined or not.

(15) In FIG. 4, a flow chart of an exemplary embodiment of the inventive method according to the second aspect of the invention is illustrated. In a first step 100, a power is measured from each antenna elements corresponding to a radiation pattern generated by an incident test signal. In a second step 101, the power distribution of the test signal is analyzed in order to calculate a calibration result.

(16) While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit or scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above described embodiments. Rather, the scope of the invention should be defined in accordance with the following claims and their equivalents.

(17) Although the invention has been illustrated and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.