Claims:1. A system (100) for amplitude direction finding, said system comprising:
one or more antennas (102) configured for direction finding (DF) measurements, the one or more antennas comprising:
a housing forming a sectoral horn (202) having a ridge structure along central axis, the sectoral horn adapted to produce main beams;
a polarizer (214) stacked in a particular fashion in front of radiating face of the sectoral horn (202), the polarizer adapted to convert a linear polarized wave into a slant polarized wave;
a layer of absorber material (212) forms an absorber lining in front of the horn aperture, the layer of absorber material adapted for beam shaping of the radiation pattern of the main beam with minimum insertion loss; and
a radome (208) located on the aperture of the sectoral horn, wherein the radome (208) covers the layer of absorber material (212) and the polarizer (214), wherein the sectoral horn (202) in combination with the polarizer, the layer of absorber material and radome adapted to control the roll-off of the main beam of the sectoral horn.

2. The system as claimed in claim 1, wherein the polarizers (214) are stacked in the radome (208) in a particular fashion to accept any type of polarized signals from external objects.

3. The system as claimed in claim 1, wherein the polarizer (214) is of curve shaped, the polarizer with the layer of absorbing material around it is used at specific location to control the roll-off in operating frequency ranges.

4. The system as claimed in claim 1, wherein the connector probe (210) is conical in structure that obtains broadband impedance matching and achieves voltage standing wave ratio (VSWR) less than 2.5:1 over 90% of the operating frequency ranges of f1-f2 GHz, wherein f1 is lower frequency and f2 is higher frequency of ultra-wideband frequency range.

5. The system as claimed in claim 1, wherein Teflon sheets are placed near the edges of the horn aperture.

6. The system as claimed in claim 5, wherein shape and size of the Teflon sheet placed near the aperture is curved and fits into the radome (208) such that the sidelobe levels below -9.5 dBc is obtained which is valid for the operating frequency ranges of f1-f2 GHz.

7. The system as claimed in claim 1, wherein the main beam symmetry with roll-off the radiation pattern specified by way of using the layer of absorbing material.

8. The system as claimed in claim 7, wherein the selection and positioning of the layer absorbing materials facilitates shaping of the radiation pattern.

9. A method (600) for amplitude direction finding, said method comprising
performing (602), by one or more antennas, direction finding (DF) measurements;
producing (604), by a sectoral horn, main beams, wherein a housing forming the sectoral horn having a ridge structure along central axis;
converting (606), by a polarizer, a linear polarized wave into a slant polarized wave, the polarizer stacked in a particular fashion in front of radiating face of the sectoral horn;
performing (608), by a layer of absorber material, beam shaping of the radiation pattern of the main beam with minimum insertion loss, the layer of absorber material forms an absorber lining in front of the horn aperture; and
covering (610), by a radome, the layer of absorber material and the polarizer, the radome located at the aperture of the sectoral horn, wherein the sectoral horn in combination with the polarizer, the layer of absorber material and radome adapted to control the roll-off of the main beam of the sectoral horn.

, Description:TECHNICAL FIELD
[0001] The present disclosure relates, in general, to horn antenna arrangement, and more specifically, relates to a system and method to control the roll-off of sectoral horn antenna for amplitude-based direction finding (DF) system.

BACKGROUND
[0002] Amplitude direction finders employ a multi-element direction finding antenna array with the antenna elements being fixed in position and with the rotating function being accomplished by sequentially energizing and scanning the individual antenna elements.
[0003] Efforts have been made in related art for horn antenna. An example of such horn antenna is recited in a Patent EP0961937B1, entitled “determining angle of arrival of a signal”. The patent describes the gain of the antenna element is high, frequency of operation is not mentioned, gain roll-off is in the range of 8-12 dB, polarisation of the antenna is linear and six number of antennas are required for finding the DOA. Another example is recited in a Patent US 7852277 B2, entitled “circularly polarized horn antenna”. The patent describes circularly polarised horn antenna with high gain, focused high power beam. Beam width varies by less than 5 over an operating frequency range of at least 14 GHz.
[0004] Yet another example is recited in a patent US4087817A, entitled ADF ANTENNA. The patent describes a combination of loop and sense antenna for direction finding, this will increase the system complexity. The gain of the loop antenna will be less that will reduce the target detection range of the system. The loop antenna is having either vertical polarization or horizontal polarization.
[0005] Although multiple mechanisms and frameworks exist today, these mechanisms and frameworks suffer from significant drawbacks. Hence, it is desired to develop a highly accurate amplitude direction finding system that controls the beam roll as per the requirement and beam shaping to cover entire 360° coverage by using few numbers of antennas.

OBJECTS OF THE PRESENT DISCLOSURE
[0006] An object of the present disclosure relates, in general, to horn antenna arrangement, and more specifically, relates to a system and method to control the roll-off of sectoral horn antenna for amplitude-based direction finding (DF) system.
[0007] Another object of the present disclosure is to provide a system that controls the beam roll as per the requirement and beam shaping is achieved in the elevation plane and with its positioning orientation it is possible to cover the entire 360° coverage.
[0008] Another object of the present disclosure is to provide a system that is suitable for the reception of vertical, horizontal, right hand circular polarized (RHCP), left-hand circular polarized (LHCP) and slant polarized waves without changing any mounting position.
[0009] Another object of the present disclosure is to provide a system that provides performance like circular polarized antennas.
[0010] Yet another object of the present disclosure is to provide a system that provides an antenna with water proof radome.

SUMMARY
[0011] The present disclosure relates, in general, to horn antenna arrangement, and more specifically, relates to a system and method to control the roll-off of sectoral horn antenna for amplitude-based direction finding (DF) system.
[0012] The beam widths of conventional horn antennas are less both in azimuth and elevation direction and their beam roll-off is very high after 3 dB beam width. So, multiple antennas are required for covering the complete 360° in azimuth. The main objective of the present disclosure is to solve the technical problem as recited above by controlling the beam roll as per the requirement and beam shaping is achieved in elevation plane and with its positioning orientation it is possible to cover entire 360° coverage by using only four number of antennas, which are typically used in ADF based DF system. The antenna is protected by a water proof radome having minimum electromagnetic (EM) absorption conversely having maximum transparency for all types of polarizations.
[0013] The present disclosure aims at providing antenna that finds a place in amplitude direction finding systems with enhanced sensitivity in all future Electronic Warfare (EW) systems. The antenna performance is suitable for reception of vertical, horizontal, right hand circular polarized (RHCP), left-hand circular polarized (LHCP) and slant polarized waves without changing any mounting position. It provided performance like circular polarized antennas. The antenna design caters for IP 65 water proof rating, so it can use in any platforms like ships, submarines, aircrafts, Unmanned Aerial Vehicle (UAVs), UUWAVs, Aerostats, Satellite systems, and the likes.
[0014] In an aspect, the present disclosure relates to a system for amplitude direction finding, the system comprising one or more antennas configured for direction finding (DF) measurements, the one or more antennas comprising a housing forming a sectoral horn having a ridge structure along central axis, the sectoral horn adapted to produce main beams. A polarizer stacked in a particular fashion in front of radiating face of the sectoral horn, the polarizer adapted to convert a linear polarized wave into a slant polarized wave. A layer of absorber material forms an absorber lining in front of the horn aperture, the layer of absorber material adapted for beam shaping of the radiation pattern of the main beam with minimum insertion loss. A radome located at the aperture of the sectoral horn, wherein the radome covers the layer of absorber material and the polarizer, wherein the sectoral horn in combination with the polarizer, the layer of absorber material and radome adapted to control the roll-off of the main beam of the sectoral horn.
[0015] According to an embodiment, the polarizers are stacked in the radome in a particular fashion to accept any type of polarized signals from external objects.
[0016] According to an embodiment, the polarizer is of curve shaped, the polarizer with absorbers around it is used at specific location to control the roll-off in operating frequency ranges.
[0017] According to an embodiment, the connector probe is conical in structure that obtains broadband impedance matching and achieves VSWR less than 2.5:1 over 90% of operating frequency ranges of f1-f2 GHz, wherein f1 is lower frequency and f2 is higher frequency of ultra-wideband frequency range.
[0018] According to an embodiment, Teflon sheets are placed near the edges of the horn aperture.
[0019] According to an embodiment, wherein shape and size of the Teflon sheet placed near the aperture is curved and fits into the radome such that the side lobe levels below -9.5 dBc is obtained which is valid for the operating frequency ranges of f1-f2 GHz.
[0020] According to an embodiment, the main beam symmetry with roll-off the radiation pattern specified by way of using the layer of absorbing material.
[0021] According to an embodiment, the selection and positioning of the layer of absorbing materials facilitates shaping of the radiation pattern.
[0022] In an aspect, the present disclosure relates to a method for amplitude direction finding, the method performing, by one or more antennas, direction finding (DF) measurements, producing, by a sectoral horn, main beams, wherein a housing forming the sectoral horn having a ridge structure along central axis, converting, by a polarizer, a linear polarized wave into a slant polarized wave, the polarizer stacked in a particular fashion in front of radiating face of the sectoral horn, performing, by a layer of absorber material, beam shaping of the radiation pattern of the main beam with minimum insertion loss, the layer of absorber material forms an absorber lining in front of the horn aperture and covering, by a radome, layer of absorber material and the polarizer, the radome located at the aperture of the sectoral horn, wherein the sectoral horn in combination with the polarizer, the layer of absorber material and radome adapted to control the roll off of the main beam of the sectoral horn.
[0023] 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 THE DRAWINGS
[0024] The following drawings form part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
[0025] FIG. 1 illustrates an exemplary functional component of amplitude direction finding system, in accordance with an embodiment of the present disclosure.
[0026] FIG. 2A illustrates an exemplary proposed antenna model, in accordance with an embodiment of the present disclosure.
[0027] FIG. 2B illustrates the basic simulation structure of waveguide port fed sectoral horn antenna, in accordance with an embodiment of the present disclosure.
[0028] FIG. 2C illustrates a schematic view of conical probe, in accordance with an embodiment of the present disclosure.
[0029] FIG. 2D illustrates a front view of sectoral horn without radome cover, in accordance with an embodiment of the present disclosure.
[0030] FIG. 2E illustrates a back view of sectoral horn without radome cover, in accordance with an embodiment of the present disclosure.
[0031] FIG. 3 illustrates a graphical view of VSWR of the proposed sectoral horn antenna, in accordance with an embodiment of the present disclosure.
[0032] FIG. 4A illustrates a graphical view of radiation pattern of basic sectoral horn antenna at different observational frequency points, in accordance with an embodiment of the present disclosure.
[0033] FIG. 4B illustrates a graphical view of radiation pattern of slant polarized sectoral horn antenna at different observational frequency points, in accordance with an embodiment of the present disclosure.
[0034] FIG. 5A illustrates a graphical view of radiation pattern of slant polarized sectoral horn with horizontal and vertical field components at f1 GHz, in accordance with an embodiment of the present disclosure.
[0035] FIG. 5B illustrates a graphical view of radiation pattern of slant polarized sectoral horn with horizontal and vertical field components at f2 GHz, in accordance with an embodiment of the present disclosure.
[0036] FIG. 6 illustrates an exemplary flow chart of method for amplitude direction finding, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0037] 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. If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0038] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0039] The present disclosure relates, in general, to horn antenna arrangement, and more specifically, relates to a system and method to control the roll-off of sectoral horn antenna for amplitude-based direction finding (DF) system. The present disclosure relates to design an electronic intelligence (ELINT) system having a very high sensitivity i.e., more than -90 dBm. To meet this stringent specification, high gain slant polarized sectoral horn antennas are required for amplitude-based direction-finding applications. The proposed sectoral horn antenna development is having broad impedance bandwidth with 45° slant polarization. The beam widths of conventional horn antennas are less both in azimuth and elevation direction and their beam roll-off is very high after 3 dB beam width. So, multiple antennas are required for covering the complete 360° coverage in azimuth. The system of the present disclosure enables to overcome the limitations of the prior art by adjusting the roll-off beam of the sectorial horn so that the antenna is suitable for DF measurements.
[0040] The term “roll-off” used herein refers to a factor of beamwidth, and specifies how much the gain changes over the elevation angle of the antenna.
[0041] In the proposed design, the beam roll off is controlled as per the requirement and beam shaping is achieved in elevation plane and with its positioning orientation it is possible to cover entire 360° coverage by using only a few numbers of antennas, which are typically used in ADF based DF system. The antenna is protected by a water proof radome having minimum EM absorption conversely having maximum transparency for all types of polarizations. The description of terms and features related to the present disclosure shall be clear from the embodiments that are illustrated and described; however, the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents of the embodiments are possible within the scope of the present disclosure. Additionally, the invention can include other embodiments that are within the scope of the claims but are not described in detail with respect to the following description.
[0042] FIG. 1 illustrates an exemplary functional component of amplitude direction finding system, in accordance with an embodiment of the present disclosure.
[0043] Referring to FIG. 1, the present disclosure represents a design methodology to achieve a highly accurate amplitude direction finding (DF) system (also referred to as system 100, herein) of <2° root mean square (RMS). System 100 requires a roll-off controlled horn antenna 202 shown in FIG.2A for direction finding measurements. The system 100 can include one or more antennas (102-1 to 102-4 (which are collectively referred to as antennas 102 and individually referred to as antenna 102, hereinafter)), a set of front-end modules 104, signal conditioning unit 106, advance digital receiver 108 and system controller 110. The antenna design of the system 100 caters for IP 65 waterproof rating, so it can use on any platforms such as ships, submarines, aircrafts, unmanned aerial vehicle (UAVs), aerostats, satellite systems, and the likes.
[0044] In an exemplary embodiment, the one or more antennas 102 can include four antennas. A typical 4-channel amplitude direction finding system 100 shown in FIG. 1. In another exemplary embodiment, the antenna 102 as presented in the example can be a horn antenna. As can be appreciated, the present disclosure may not be limited to this configuration but may be extended to other configurations. The horn antenna 102 is used to transmit radio waves from a waveguide 204 or collect radio waves into the waveguide for the reception.
[0045] A typical gain roll of sectorial horn antenna is around 3 dB at 90° away from beam peak at lower frequency f1 and whereas 12 dB at higher frequency f2 and the enhanced gain roll-off sectoral horn antenna 8-12 dB over entire frequency band is obtained in the present disclosure through different breakthrough technologies for making it suitable for ADF and achieving the DF accuracy less than 2° with less numbers of elements. Side lobe level is quite less in lower range of frequencies as such of -5 dBc in typical horn structure which is enhanced to maintain a safe level of –9 dBc in entire range of frequency, where dBc refers to decibels relative to carrier.
[0046] The one or more antennas 102 configured for direction finding (DF) measurements, the one or more antennas 102 can include a housing forming a sectoral horn 202 having a ridge structure along central axis, the sectoral horn 202 shown in FIG. 2B adapted to produce main beams. In an embodiment, the centre ridged sectorial horn antenna 202 geometry is simulated to cater f1-f2 GHz of a frequency band. The lower frequency is f1 and f2 is higher frequency of ultra-wideband frequency range.
[0047] A coaxial feed network for broadband impedance matching is designed and incorporated with antenna simulation. A connector probe 210 shown in FIG. 2C is used in a practical feeding network for the transition of coaxial SubMiniature Version A (SMA) connector to waveguide. The probe 210 connects SMA connector centre pin to lower ridge of the horn antenna 202. The feed network and its position are critical as it plays an important role in the performance of antenna for ultra-wide frequency ranges.
[0048] The one or more antenna 102 used in the system 100 can be circularly polarized or slant polarized to receive all kinds of incoming signals. A polarizer 214 is shown in FIG. 2D stacked in a particular fashion in front of radiating face of the sectoral horn 202. In an exemplary embodiment, the polarizer 214 is a 45° slant polarizer, where the polarizer 214 is stacked in a particular way in the front of radiating face of the sectoral horn antenna 202 to convert a linear polarized wave into a slant polarized wave.
[0049] A layer of absorber material 212 (also referred to as absorber 212) forms an absorber lining in front of the horn aperture, the layer of absorber material 212 adapted for beam shaping of the radiation pattern of the main beam with a maximum insertion loss of < 0.2 dB. The selection and positioning of absorbing materials 212 facilitate the shaping of the radiation pattern. The main beam symmetry (±3° at 90°) with roll-off the radiation pattern specified by way of using the absorbing material.
[0050] A radome 208 shown in FIG. 2A located at the aperture of the sectoral horn 202, the radome 208 can cover the layer of absorber material 212 and the polarizer 214 and can be fixed with the main frame of the antenna using screws. The sectoral horn 202 in combination with the polarizer 214, the layer of absorber material 212 and radome 208 adapted to control the roll-off of the main beam of the sectoral horn 202. The roll-off of the radiation pattern is 10 ± 1.2 dB at 90° away from the beam peak.
[0051] The radome 208 can cover the layer of absorber material 212 and the polarizer 214 and can be fixed with the main frame of the antenna using screws. The provision of a flat gasket is also providing in between to make it waterproof and comply with IP65 standards. The Teflon sheets are placed near the edges of the horn aperture. The shape and size of the Teflon block placed near the aperture is curved and fits into the radome 208 such that the sidelobe levels below 9.5 dB are obtained which is valid for the operating frequency ranges of f1-f2 GHz
[0052] After generating slant polarization from the antenna 202 there are further few more major challenges that include controlling the radiation pattern to achieve the required gain roll-off at beam angle of ± 90° from bore sight while maintaining 45° slant polarization. The horizontal and vertical field components amplitude and phase imbalance should be controlled and the back-lobe levels should be controlled to a suitable level of -9 dBc in the entire frequency range of f1-f2 GHz. The above challenges shall be met without changing the dimensions of the sectoral horn antenna 202.
[0053] To address the above challenges, the present disclosure overcomes the first and second limitations by performing numerical experimentation with the shape of polarizer 214, flaring of the horn antenna 202 and thickness of absorbers 212. A curve-shaped polarizer 214 with absorbers 212 around it is used at a specific location to control the roll-off in the entire frequency range. The present disclosure overcomes third limitation of back lobe radiation by using a metal plate 206, where the metal plate 206 is covered with the absorbers 212 with some thickness so that it should not have any adverse effect on the main beam pattern.
[0054] FIG. 2A illustrates an exemplary proposed antenna model, in accordance with an embodiment of the present disclosure.
[0055] As depicted in FIG. 2A, the basic structure of antenna 102 employing electronically controlled radiating elements that can include sectoral horn 202, waveguide 204, metal plate 206, radome 208, connector probe 210 shown in FIG. 2C, a layer absorber material 212 and polarizer 214 shown in FIG. 2D. The sectoral horn antenna 202 comes under the linearly polarized antenna category. Any direction-finding system can be capable of receiving all kinds of polarized waves. The antenna used in the system 100 can be circularly polarized or slant polarized to receive all kinds of incoming signals.
[0056] The sectoral horn antenna 202 can be made suitable for ADF system 100 by using the 45° slant polarizer 214 stacked in a particular fashion and positioned in the front of radiating face of the sectoral horn antenna 202. The polarizer 214 is designed to convert the linear polarized wave into the slant polarized wave. The slant polarized antenna has the advantage of receiving both horizontal and vertical polarized waves with a loss of 3dB.
[0057] The sectoral horn antenna 202 with method of using polarizer 214 and radome 208 is proposed to achieve the below characteristics in the present disclosure. The characteristics are as follows:
• Controlling the radiation pattern to achieve required gain roll-off at beam angle of ± 90° from bore sight while maintaining 45° slant polarization.
• Controlling the horizontal and vertical field components amplitude and phase imbalance
• Controlling the back-lobe levels to a suitable level of -9 dBc in the entire frequency range of f1-f2 GHz
[0058] The above characteristics shall be met without changing dimensions of the sectoral horn antenna 202.
[0059] FIG. 2B illustrates the basic simulation structure of waveguide port fed sectoral horn antenna, in accordance with an embodiment of the present disclosure. The horn antenna 202 depicted in FIG. 2B is used to transmit radio waves from the waveguide 204 or collect radio waves into the waveguide for the reception.
[0060] FIG. 2C illustrates a schematic view of conical probe, in accordance with an embodiment of the present disclosure. The connector probe 210 is used in the practical feeding network for the transition of coaxial SMA connector to waveguide. The conical probe 210 connects SMA connector centre pin to lower ridge of the horn antenna 102. The dimension of the probe 210 and probe to ridge connection location may have a significant effect on voltage standing wave ratio (VSWR) bandwidth of the antenna. The connector probe 210 is conical in structure that obtains broadband impedance matching and achieves VSWR less than 2.5:1 over 90% of operating frequency ranges of f1-f2 GHz
[0061] FIG. 2D illustrates a front view of sectoral horn without radome cover, in accordance with an embodiment of the present disclosure. The polarizer 214 can include horizontal and 45° slant metallic strips of uniform width with specific separation among them, etched on Rogers RT duroid 5880 substrates. The printed circuit board (PCBs) of the polarizer 214 are separated by a dielectric spacer.
[0062] FIG. 2E illustrates a back view of sectoral horn without radome cover, in accordance with an embodiment of the present disclosure. The metal plate 206 is covered with the absorbers 212 with some thickness so that it should not have any adverse effect on the main beam pattern.
[0063] The embodiments of the present disclosure described above provide several advantages. The present disclosure provides the system 100 that controls the beam roll as per the requirement and beam shaping is achieved in the elevation plane and with its positioning orientation it is possible to cover the entire 360° coverage. The system 100 is suitable for the reception of vertical, horizontal, right hand circular polarized (RHCP), left-hand circular polarized (LHCP) and slant polarized waves without changing any mounting position. The system provides performance like circular polarized antennas and provides an antenna with waterproof radome.
SIMULATION EXPERIMENTAL RESULTS
[0064] FIG. 3 illustrates a graphical view of VSWR of the proposed sectoral horn antenna, in accordance with an embodiment of the present disclosure. As depicted in FIG. 3. the designed antenna is simulated in CST 2020. Simulation results show VSWR < 3 from f1-f2 GHz frequency band of operation.
[0065] FIG. 4A illustrates a graphical view of radiation pattern of basic sectoral horn antenna at different observational frequency points, in accordance with an embodiment of the present disclosure. The radiation pattern at different frequencies from f1-f2 GHz are shown in the FIG. 4A and FIG. 4B respectively. The peak realized gain variation of slant polarized antenna is 6.25 ±1.85 dBi over the entire frequency band of f1-f2 GHz.
[0066] FIG. 4B illustrates a graphical view of radiation pattern of slant polarized sectoral horn antenna at different observational frequency points, in accordance with an embodiment of the present disclosure. The radiation pattern results show a variation in gain roll-off (9.78± 0.83 dB) with respect to frequency as depicted in FIG. 4B, at ±90° beam angle from the bore site.
[0067] FIG. 5A illustrates a graphical view of radiation pattern of slant polarized sectoral horn with horizontal and vertical field components at f1 GHz, in accordance with an embodiment of the present disclosure. The radiation pattern shape of horizontal and vertical component with equivalent slant polarization, lower frequency f1 GHz band edge is shown in FIG. 5A.
[0068] FIG. 5B illustrates a graphical view of radiation pattern of slant polarized sectoral horn, with horizontal and vertical field components at f2 GHz, in accordance with an embodiment of the present disclosure. The radiation pattern shape of horizontal and vertical component with equivalent slant polarization, higher frequency f2 GHz band edge is shown in in FIG. 5B. Results of antenna are listed in table 1 below.
S. No.
Frequency (GHz)
45° Slant polarization Horizontal Polarized component Vertical Polarized component
Peak gain at‘0°’ Roll off at ‘90°’ Roll off at ‘-90°’ Roll off at ‘90°’ Roll off at ‘-90°’ Roll off at ‘90°’ Roll off at ‘-90°’
1 f1 4.41 10.20 10.23 9.91 9.97 11.65 11.56
2 f0 7.10 9.16 9.18 11.59 11.62 7.14 7.19
3 f2 7.42 10.77 10.70 10.13 10.17 11.21 11.09
Table 1: Results of antenna
[0069] However, these are just exemplary values, and that the actual values can be a wide range, and the values included here are just for illustrative purposes other values and integer multiples are possible as well.
[0070] FIG. 6 illustrates an exemplary flow chart of method for amplitude direction finding, in accordance with an embodiment of the present disclosure.
[0071] Referring to FIG. 6, method 600 for amplitude direction finding. At block 602, the one or more antennas configured for direction finding (DF) measurements. At block 604, the one or more antennas can include a housing forming a sectoral horn having a ridge structure along central axis, the sectoral horn adapted to produce main beams.
[0072] At block 606, the polarizer stacked in a particular fashion in front of radiating face of the sectoral horn, the polarizer adapted to convert a linear polarized wave into a slant polarized wave.
[0073] At block 608, the layer of absorber material forms an absorber lining in front of the horn aperture, the layer of absorber material adapted for beam shaping of the radiation pattern of the main beam with minimum insertion loss. At block 610, the radome located at the aperture of the sectoral horn, wherein the radome 208 covers the layer of absorber material 212 and the polarizer 214, wherein the sectoral horn in combination with the polarizer, the layer of absorber material and radome adapted to control the roll-off of the main beam of the sectoral horn.
[0074] The method of controlling the roll-off of the main beam of sectoral horn antenna through design of particular shape of sectoral horn 202, shape and position of feed point 210, method of stacking the polarizers 214 and absorbers 212 in the radome 208 and method of placement of radome 208 on the aperture of the horn, where in the radiation characteristics are achieved as follows:
• Roll-off of the radiation pattern is 10 ± 1.2 dB at 90° away from the beam peak.
• Main beam symmetry (±3° at 90°) with roll-off the radiation pattern specified by way of using the absorbing material.
• Selection and positioning of absorbing materials to achieve shaping of the radiation pattern.
• Beam shaping of the radiation pattern is achieved with minimum insertion loss (< 0.2 dB) by placement of absorbers in front of horn aperture.
[0075] The shape and position of feed point to achieve VSWR <2.5 over 90% of operating frequency ranges of f1-f2 GHz. The polarizers 214 are stacked in the radome 208 in a particular fashion to accept any type of polarized signals from the external objects. The method of achieving the side lobe levels below -9.5 dBc which is valid for the entire frequency band of f1-f2 GHz through placement of Teflon sheets near the edges of the horn aperture. The shape and size of the teflon block placed near the aperture is curved and fits into the radome 208. The broadband impedance matching is achieved through conical feed structure and VSWR less than 2.5:1 over 90% of f1-f2 GHz frequency ranges is achieved.
[0076] It will be apparent to those skilled in the art that the system 100 of the disclosure may be provided using some or all of the mentioned features and components without departing from the scope of the present disclosure. While various embodiments of the present disclosure have been illustrated and described herein, it will be clear that the disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the disclosure, as described in the claims.

ADVANTAGES OF THE PRESENT DISCLOSURE
[0077] The present disclosure provides a system that controls the beam roll as per the requirement and beam shaping is achieved in the elevation plane and due to that it is possible to cover the entire 360° coverage.
[0078] The present disclosure provides a system that is suitable for the reception of vertical, horizontal, right hand circular polarized (RHCP), left-hand circular polarized (LHCP) and slant polarized waves without changing any mounting position.
[0079] The present disclosure provides a system that provides performance like circular polarized antennas.
[0080] The present disclosure provides a system that provides an antenna with waterproof radome.