Claims:1. A system for generating calibrated broadening beam broadening coefficients for an Active Phase Array Radar having a plurality of antenna elements, the system comprising:
a controlling unit having one or more processors coupled with a memory for storing instruction that on execution make one or more processors to:
receive a first signal pertaining to a pre-defined calibration ratio, and a second signal pertaining to first phase angle of the known calibration signal, and correspondingly generate a calibrated phase signal;
mix the calibrated phase signal and one or more broadening coefficients to correspondingly generate a resultant phase angle;
convert the resultant phase angle into a predefined range, and into corresponding second phase angle; and
generate calibrated transmit beam coefficients based on the resultant phase angle.
2. The system as claimed in claim 1, wherein the control circuit comprises a Field Programmable Grid Array (FPGA).
3. The system as claimed in claim 1, wherein the calibrated phase signal comprises zero relative phases across channels of the plurality of antenna elements.
4. The system as claimed in claim 4, wherein the zero relative phases are achieved by adding the calibration I Q signal to the ADC, and adding negated first phase angle of each channel of the ADC to pre-defined calibration ratios.
5. A method for generating calibrated broadening beam broadening coefficient for an active phase radar having a plurality of antenna elements, the method comprising:
receiving, by one or more processors, a first input pertaining to a pre-defined calibration ratio, and a second input pertaining to first phase angle of the known calibration signal, and correspondingly generate a calibrated phase signal;
mixing, by the one or more processors, the calibrated phase signal and one or more broadening coefficients to correspondingly generate a resultant phase angle;
converting, by the one or more processors, the resultant phase angle into a predefined range, and into corresponding second phase angle; and
generate calibrated transmit beam coefficients based on the resultant phase angle.
, Description:TECHNICAL FIELD
[0001] The present disclosure relates to the field of active phased array radar. More particularly the present disclosure relates to a system and method of transmit beam broadening for active phased array radar.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Conventional communication systems are designed with omni-directional transmissions that are good for control and broadcast data to all users. However, they are often inefficient for user-specific data communication since the energy is sent in all directions. Directional communication is advantageous for user-specific data communication, however design of the control and broadcast channel for multiple users is challenging. For broadcast or control data purpose, a large beamwidth is required for better coverage. There are methods of increasing beamwidth of the transmit signals. Some of the conventional methods for beam broadening include turning off parts of antenna array however this can result in loss of output power along with beam forming loss due to small element array. Phase only beam broadening is also known however this method is based on searches and do not provide a systematic approach for beam broadening.
[0004] There is, therefore, a need of an improved method of generating calibrated beam broadening coefficients for active phased radar.

OBJECTS OF THE PRESENT DISCLOSURE
[0005] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as listed herein below.
[0006] It is an object of the present disclosure to provide a system and method for generating calibrated beam broadening coefficients for an Active Phased Array Radar in the elevation.
[0007] It is an object of the present disclosure to provide a system and method for generating calibrated beam broadening coefficients for an Active Phased Radar in the elevation with high accuracy.
[0008] It is an object of the present disclosure to provide a system and method for generating calibrated beam broadening coefficients for an Active Phased Radar in the elevation which increases flexibility of the system.

SUMMARY
[0009] The present disclosure relates to the field of active phased array radar. More particularly the present disclosure relates to a system and method of calibration and transmit beam broadening for active phased array radar.
[0010] An aspect of the present disclosure pertains to a system for generating calibrated beam broadening coefficient for an active phase radar having a plurality of antenna elements. The system includes a controlling unit having one or more processors coupled with a memory for storing instructions that on execution make one or more processors to receive a first signal pertaining to a pre-defined or known calibration ratio, and a second signal pertaining to phase angle of a known signal of the plurality of antenna elements, and correspondingly generate a calibration phase signal. Broadening coefficients are generated depending upon the final beamwidth required by generating phase angle for each element of the antenna using Sub array Method. Mix the calibration phase signal and one or more broadening coefficients to correspondingly generate a resultant phase angle. Convert the resultant phase angle into corresponding second phase angle. Generate calibrated transmit beam coefficients based on the resultant phase angle which can be used to broaden beamwidth of transmit signal.
[0011] In an aspect, the control circuit may include a Field Programmable Grid Array (FPGA). The calibrated phase signal may include zero relative phases across channels of phased array antenna. The zero relative phases may be achieved by negating first phase angle generated using a known calibration signal and adding with calibration ratios measured in Near field test facility.
[0012] In yet another aspect of the present disclosure pertains to a method for generating calibrated beam broadening coefficient for an active phase radar having a plurality of antenna elements. The method may include receiving, by one or more processors, a first input pertaining to a pre-defined calibration ratio, and a second input pertaining to respective first phase angle of the calibration signals of the plurality of antenna elements, and correspondingly generate a calibrated phase signal. Mixing, by the one or more processors, the calibration phase signal and one or more broadening coefficients to correspondingly generate a resultant phase angle. Converting, by the one or more processors, the resultant phase angle into a predefined range, and into corresponding second phase angle. Generating calibrated transmit beam coefficients based on the resultant phase angle.
[0013] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF DRAWINGS
[0014] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. The diagrams are for illustration only, which thus is not a limitation of the present disclosure.
[0015] In the figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
[0016] FIG. 1 illustrates an exemplary module diagram of system for generating calibrated beam broadening coefficients for an Active Phased Radar, in accordance with an embodiment of the present disclosure.
[0017] FIG. 2 illustrates an exemplary software flow, implemented on FPGA, for combining broadening weights or coefficients with calibration coefficients pertaining to calibration phase signal, in accordance with an embodiment of the present disclosure.
[0018] FIG. 3 illustrates an exemplary method of system for generating calibrated beam broadening coefficients for an Active Phased Radar, in accordance with an embodiment of the present disclosure.
[0019] FIG. 4A illustrates Matlab simulated broadened beam for 20degree in elevation, FIG. 4B illustrates Matlab simulated broadened beam for 9.6degree in elevation, and FIG. 4C illustrates Matlab simulated broadened beams for 20degree and 9.6 Degrees in elevation along with original beam of 3.2 degrees, in accordance with an embodiment of the present disclosure.
[0020] FIG. 5A illustrates Radiation pattern calculated for two subarrays independently, and FIG. 5B illustrates radiation patterns accumulated to get the desired transmit beam widened to 20 degrees, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION
[0021] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0022] In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to one skilled in the art that embodiments of the present invention may be practiced without some of these specific details.
[0023] The present disclosure relates to the field of active phased array radar. More particularly the present disclosure relates to a system and method of beam broadening for active phase radar.
[0024] The present disclosure elaborates upon to a system for generating calibrated beam broadening coefficient for an active phase radar having a plurality of antenna elements. The system includes a controlling unit having one or more processors coupled with a memory for storing instructions that on execution make one or more processors to receive a first signal pertaining to a pre-defined calibration ratio, and a second signal pertaining to respective first phase angle of the calibration signals of the plurality of antenna elements, and correspondingly generate a calibrated phase signal. Mix the calibration phase signal and one or more broadening coefficients to correspondingly generate a resultant phase angle. Convert the resultant phase angle into a predefined range, and into corresponding second phase angle. Generate calibrated transmit beam coefficients based on the resultant phase angle.
[0025] In an embodiment, the control circuit can include a Field Programmable Grid Array (FPGA).
[0026] In an embodiment, the calibrated phase signal can include zero relative phases across channels of antenna.
[0027] In an embodiment, the zero relative phases can be achieved by adding the calibration ratio and negated first phase angle.
[0028] A method for generating calibrated beam broadening coefficients for an active phase radar having a plurality of antenna elements. The method can include receiving, by one or more processors, a first input pertaining to a pre-defined calibration ratio, and a second input pertaining to respective first phase angle of a pre-defined or known calibration signal, and correspondingly generate a calibrated phase signal. Mixing, by the one or more processors, the calibrated phase signal and one or more broadening coefficients to correspondingly generate a resultant phase angle. Converting, by the one or more processors, the resultant phase angle into a predefined range, and into corresponding second phase angle. Generating calibrated transmit beam coefficients based on the resultant phase angle, by the one or more processors.
[0029] FIG. 1 illustrates an exemplary module diagram of system for generating calibrated beam broadening coefficients for an Active Phased Radar, in accordance with an embodiment of the present disclosure.
[0030] As illustrated, an exemplary module diagram of the proposed system 100 for generating calibrated beam broadening coefficients for an active phase radar, can include a controlling unit that can further include one or more processor(s) 102. The one or more processor(s) 102 can be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, logic circuitries, and/or any devices that manipulate data based on operational instructions. Among other capabilities, the one or more processor(s) 102 are configured to fetch and execute computer-readable instructions stored in a memory 106 of the system 100. The memory 104 can store one or more computer-readable instructions or routines, which may be fetched and executed to create or share the data units over a network service. The memory 104 can include any non-transitory storage device including, for example, volatile memory such as RAM, or non-volatile memory such as EPROM, flash memory, and the like.
[0031] The system 100 can also include an interface(s) 106. The interface(s) 106 can comprise a variety of interfaces, for example, interfaces for data input and output devices, referred to as I/O devices, storage devices, battery charging and the like. The interface(s) 106 can also provide a communication pathway for one or more components of the system 100. Examples of such components include, but are not limited to, processing engine(s) 108 and data 112.
[0032] The processing engine(s) 108 can be implemented as a combination of hardware and programming (for example, programmable instructions) to implement one or more functionalities of the processing engine(s) 108. In examples described herein, such combinations of hardware and programming may be implemented in several different ways. For example, the programming for the processing engine(s) 108 can be processor executable instructions stored on a non-transitory machine-readable storage medium and the hardware for the processing engine(s) 108 can comprise a processing resource (for example, one or more processors), to execute such instructions. In the present examples, the machine-readable storage medium can store instructions that, when executed by the processing resource, implement the processing engine(s) 108. In such examples, the system 100 can comprise the machine-readable storage medium storing the instructions and the processing resource to execute the instructions, or the machine-readable storage medium may be separate but accessible to the system 100 and the processing resource. In other examples, the processing engine(s) 108 can be implemented by electronic circuitry.
[0033] The data 110 can comprise data that is either stored or generated as a result of functionalities implemented by any of the components of the processing engine(s) 108 of the system 100. The present disclosure relates to system 100 for broadening beam of a simulated signal of an active phase radar having a plurality of antenna elements. In order perform the above-mentioned verification, the system 100 can include a calibrated phase generation module 112, which can be configured to receive a first signal pertaining to a pre-defined calibration ratio, and a second signal pertaining to respective first phase angles of each channel, computed using known calibration signal inputted in a calibration (cal) port of the system. The known calibration signal can be inputted into cal channel ADC via calibration port serially for each transmit channel. Phase of each channel can be computed to generated calibration factors. These calibration factors are added with the pre-defined calibration ration before further addition with broadening weights or coefficients. Based on the first input and the second input, the calibrated phase generation module generates a calibrated phase signal. The calibrated phase signal can include zero relative phases across all channels of antenna, and the zero relative phases can be achieved by adding the calibration ratio and negated first phase angle.
[0034] The respective first phase angle of the transmit signals of the plurality of antenna elements can be converted into first I Q signals, and the first I Q signals are converted into phase angles and can be negated before adding to the pre-defined calibration ratio. The calibrated phase signal can be generated by adding the pre-defined calibration ratio, and the negated phase angles generated from the first I Q signals.
[0035] In an embodiment, the system can include a broadening weight or coefficients combining module 114 that can be configured to receive the calibrated phase signal, and one or more broadening coefficients. On the basis of the calibrated phase signal and the one or more broadening coefficient, the broadening weight combining engine can generate a resultant phase angle. The transmit broadening coefficients/weights can be converted in to second I Q signals and further into second phase angle and then can be added to the calibrated phase signal to generate the resultant phase angle.
[0036] In an embodiment, the system can include a calibrated transmit beam coefficient generation module 116 that can be configured to generate the calibrated beam coefficients based on the resultant phase angle received from the broadening weight or coefficients combining module. The resultant phase angle can be converted into a predefined range of +180 deg. to -180 deg. The converted phase angle can be further converted in to third I Q signals and can be normalized before generating calibrated transmit beam coefficients. The calibrated transmit beam coefficients can be further used to broaden the beam (can also be referred as beamwidth, herein) of the transmit signal based on the calibrated transmit beam coefficients. The control circuit can include a Field Programmable Grid Array (FPGA).
[0037] FIG. 2 illustrates an exemplary software flow, implemented on FPGA, for combining broadening weights or coefficients with calibration coefficients pertaining to calibration phase signal, in accordance with an embodiment of the present disclosure.
[0038] As illustrated, the first I Q signals can be generated by using an analog to digital converter (ADC). The first I Q signals can be computed by inputting a calibration (cal) I Q signal to the ADC. Phases can be Computed from the first I Q signal entering the system and are added to CR Values after negating using a first adder block of the FPGA. Transmit broadening weights can be converted into second I Q signals can further into second phase angle before adding to the calibrated phase signal, to generate the resultant phase angle, through a second adder block of the FPGA. The resultant phase angle can be converted into a pre-defined range of +180 deg. to -180 deg. before it is converted into third I Q signals through a sine and cosine block of the FPGA. Normalized third I Q signals can be fed to a digital to analog (DAC) to generate calibrated transmit broadening weights or coefficients. The calibrated transmit broadening weights or coefficients can be input to an analog mixer for broadening beam of the transmit signals.
[0039] FIG. 3 illustrates an exemplary method of system for generating calibrated beam broadening coefficients for an Active Phased Radar, in accordance with an embodiment of the present disclosure.
[0040] As illustrated, at step 302, a method 300 for broadening beam of a transmit signal of an active phase radar can include receiving, by one or more processors, a first input pertaining to a pre-defined calibration ratio, and a second input pertaining to respective first phase angle of the known calibration signals of the plurality of antenna elements, and correspondingly generate a calibrated phase signal.
[0041] In an embodiment, at step 304, the method 300 can include mixing, by the one or more processors, the calibration phase signal and one or more broadening coefficients to correspondingly generate a resultant phase angle.
[0042] In an embodiment, at step 306, the method 300 can include converting, by the one or more processors, the resultant phase angle into a predefined range, and into corresponding second phase angle. At step 308, the method 300 can include generating calibrated transmit beam coefficients based on the resultant phase angle. At step 310 the method 300 can include broadening, by the one or more processors, the beam of the transmit signal based on the calibrated transmit beam coefficients.
[0043] FIG. 4A illustrates Matlab simulated broadened beam for 20 degree in elevation, FIG. 4B illustrates Matlab simulated broadened beam for 9.6degree in elevation, and FIG. 4C illustrates Matlab simulated broadened beams for 20 degree and 9.6 Degrees in elevation along with original beam of 3.2 degrees, in accordance with an embodiment of the present disclosure.
[0044] FIG. 5A illustrates Radiation pattern calculated for two subarrays independently, and FIG. 5B illustrates radiation patterns accumulated to get the desired transmit beam widened to 20 degrees, in accordance with an embodiment of the invention.
[0045] As illustrated, broadened beam for 20 degrees in elevation is represented as ‘X’, broadened beam for 9.6 degrees in elevation is represented as ‘Y’, and original beam of 3.2 degrees is represented as ‘Z’ in the FIGs 4A-4C. It can be seen from the figures that the beam is broadened significantly using the proposed system and method for broadening transmit beam of an active phase radar having a plurality of antenna elements.
[0046] In an embodiment, to reduce the revisit time in search mode, one may broaden the main beam on transmit and apply multiple receive beams formation by dividing the aperture to subarrays and form squinted beam from each.


Where:
M = number of sub arrays
Ns = number of elements for the sub array.
m = subarray index
n = element index within each subarray
? = kdsin(?)
? = elevation angle over which the array is steered
d = inter-element antenna spacing
k = 2p/?
Broaden weights can be calculated using equation:

Online Phase calibration values are computed by finding the phase of each channel using the equation:
=O°
Known calibration signal can be sent to all channels serially and can be digitized using ADC block. Phase of each channel (also referred as transmit signals of the plurality of antenna elements) is calculated using above formula and calibration coefficients are generated. This can be done by negating the calculated first phase angle e.g. O° and storing it as phase calibration value as -O° channel wise. These phase calibration values can be referred as calibration path (CP) values.
[0047] In an embodiment, calibration in near field test facility (NFTR) is done before deploying Radar in field. In this process, a probe is positioned in front of the particular channel under calibration. Calibration ratio (CR) values are calculated by the NFTR setup for each channel. The Calibration ratio (CR) values and calibration path (CP) values can be added to arrive at resultant calibration phases to bring all channels phases equal to zero degree.
[0048] Moreover, in interpreting the specification, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
[0049] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0050] The proposed invention provides a system and method for generating calibrated beam broadening coefficients for an Active Phased Radar in the elevation.
[0051] The proposed invention provides a system and method for generating calibrated beam broadening coefficients for an Active Phased Radar in the elevation with high accuracy.
[0052] The proposed invention provides a system and method for generating calibrated beam broadening coefficients for an Active Phased Radar in the elevation which increases flexibility of the system.