Title of Invention	"A HIGH POWER LINEAR PHASED ARRAY ANTENNA"
Abstract	The high power linear phased array antenna comprises more than two radiating elements. Each of the elements comprises a first conducting plate integrated with a second conducting plate. The second conducting plate constitutes the first conducting plate of the next successive radiating element. Each of the radiating elements comprises a closed end absorptive backwall and a coaxial connector.

Full Text

PRIOR ART The present invention relates to the field of antennas and more particularly, to the field of phased array antenna employing multiple H-oiane sectoral horn antenna for transmit or receive applications. A phased array antenna generally consists of a group of radio frequency energy radiating elements placed in close proximity to each other so that they provide the collective capability to steer a radio frequency beam. The type of radiating elements to be used depends on the desired operational characteristics of the antenna. The elements typically are arranged in a regular pattern with a spacing 'd' satisfying the no grating lobe condition in the visible region, given by: d/λ Where X is the wavelength of the maximum RF energy to be received or transmitted by the antenna and θ.sub.s is the maximum scan angle from bore sight. If the elements are very close together, they will degrade each other s performance unless special care is taken. If they are far apart compared to the wavelength of interest, they cease to act collectively and produces multiple undesired lobes in the visible region i.e. angle over which the beam can be scanned. The amplitude and phase of the input power of each element controls the beam width and angle of maximum scan of the array antenna. The use of phased array antenna permits the achievement of desirable applications such as the steering of the beam with simple elements with little intrinsic capability During the past several years there has been growing interest in developing wide band phased array antennas, especially antennas, which can handle relatively high RF power for jamming application and can provide scanning of beam over wide angles. Printed, circuit radiators are ruled out for above purposes, as these cannot handle high-power. Hence, double ridge waveguide horn antenna becomes the preferred choice as it provides wide bandwidth and high power handling capability. Also, the dimension of the ridged waveguide horn can just fit into the required spacing for an array working over higher microwave and millimeter wave frequency bands. This physical constraint cn the size increases with maximum scan angle coverage required by the array and the maximum frequency of operation. One of the antennas, known in the prior art, has been described in US Patent No. 3,881,178 and US Patent No. 5,995,056. These antenna systems comprise a reflector to control the beam width. However, the additional structure. in the form of reflector, added to the antenna system makes it more complex and cumbersome. Further, these types of antennas suffer from the disadvantage of radiating large amount of radio frequency power as undesired lobes nad even failure in case high power transmission. Yet another antenna, known in the prior art, has been described in US Patent No. 4,353,074. Such antennas are basically ridge wave guide type antennas, which are fed by a coaxial transmission line through jack type coaxial connectors, all fixed in a row at regular interval within the inter element spacing However, these antennas pose problems relating to mating of plug type coaxial connectors of inter connecting cables with the jack type coaxial connectors of array elements (which are placed in a row within small inter element spacing). The spacing requirement is further strained if RF beam is to be scanned over large angles at higher end of operating frequency. Further in the above mentioned antennas, known in the prior art, Impedance matching between a coaxial line and ridged wave guide line is usually achieved by inserting tuning screws in the wave guide region which is highly cumbersome, time taking and non repeatable process. Complicated modifications in the wave-guide are some time used but is not preferred as it may affect the required bandwidth, power handling characteristics or scan angle coverage. OBJECTS OF THE INVENTION: Primary object of the invention is to provide a high power phased array antenna wherein the each element is capable of conducting up to 100 watts of radio frequency energy in the frequency range 7.5 to 18 GHz. Another object of the invention is to provide a high power phased array antenna, wherein the each element is capable of radiating continuous wave energy of 100 watts over a large period of time without failure. Still another object of the invention is to provide a high power phased array antenna, in which the scan angle of antenna can be varied between -45° and +45°. Yet further object of the invention is to provide a high power phased array antenna, which can be used for jamming RF signals over wide frequency band and wide scan angles. Still further object of the invention is to provide a high power phased array antenna, which can be used both for the transmission as well as reception of the electromagnetic energy. Yet further object of the invention is to provide a high power phased array antenna, which can provide wideband impedance matching without using conventional tuning screws through the broad/back walls of wave-guide. Still further object of the invention is to provide a high power phased array antenna, which has a relatively high power handling coaxial input connector for compact and reliable array system. Yet further object of the invention is to provide a high power phased array antenna wherein the adjacent radiating elements have smoothly bent transmission line in opposite direction, in the same plane, for staggered coaxial feed output. Still further object of the invention is to provide a high power phased array antenna, which is relatively simpler and modular in construction and which can generate a linear array of any number of radiating elements by simple process of stacking together the additional number of radiating elements with mechanical means. Yet further object of the invention is to provide a high power phased array antenna, in which an antenna element can be realized within the required inter element spacing decided by no granting lobe condition in the visible region of scanning over relatively wide frequency band especially at the higher end of microwave and millimeter wave operating frequency. Yet further object of the invention is to provide a high power phased array antenna, which utilizes a H-plane sectoral horn as an aperture control device having a selected flare angle and aperture shape in accordance with the laws of optics for limiting the beam width in the plane orthogonal to the plane of scanning of the array. The aperture control device used in the invention can be designed to get a wide range of elevation beam widths. DESCRIPTION OF THE INVENTION According to this invention there is provided a high power linear phased array antenna comprising : m number of radiating element (1) having (m+1) number of conducting plates stacked together with mechanical means, each radiating element (1) comprising a first conducting plate (25) integrated with a second conducting plate (26), said second conducting plate (26) being the said first conducting plate of a succeeding radiating element and mechanically coupled with a third conducting plate (27), wherein, the mth radiating element comprising mth conducting plate of the (m-1)th radiating element mechanically coupled with the (m+l)th conducting plate of the said mth radiating element, where m is a positive integer and m 2; wherein, each of the said radiating element further comprises a closed end absorptive back wall (4) and a coaxial connector (3) for getting input power. In accordance with the present invention, there is provided a high power phased array antenna wherein the each element is capable of conducting upto 100 watts of radio frequency energy in the frequency range of 7.5 to 18 GHz. The array of the present invention can provide angular coverage from -45° to 45°. The high power antenna of the present inventin is capable of radiating continuous wave energy of 100 watts over a large period of time without failure. The scan angle of present antenna can be varied between -45° and 45°. The antenna of the present invention utilizes standard ridge wave guide structures thereby making the fabrication of the antenna relatively less complex. The high power antenna of the present invention is modular in approach and the number of radiating elements can be increased as per the operational requirement just by stacking the additional radiating elements with mechanical means. The antenna of the present invention utilizes a coaxial input connector, which is capable of handing high power and it does not need conventional tuning screws for wide band impedance matching between coaxial and waveguide types of transmission lines. The antenna of the present invention is highly compact and is capable of use in transmission as well as reception of electromagnetic energy. Further, it can be used for jamming radio frequency signals over wide frequency band and wide scan angles. In the antenna system of the present invention, an antenna element can be realized within the required inter element spacing decided by no grating lobe condition in the visible region of scanning over relatively wide frequency band especially at the higher end of microwave and millimeter wave operating frequency. ACCOMPANYING DESCRIPTION OF THE/DRAWINGS: Any further characteristics, advantages and applications of the invention will become evident from the detailed description of the preferred embodiment which has been described and illustrated with the help of following drawings wherein, Fig.1 is one view of the high power linear phased array antenna of the present invention Fig 2 provides another view of the high power linear phased array antenna of the present invention Fig 3 also provides yet another view of the high power linear phased array antenna of the present invention Fig 4 is an exploded view of the two conducting plates forming one radiating element Fig 5 shows one type of the end plate (type -1) used to form the antenna element as one end of the array Fig 6 shows another typ3 of end plate (type-2) that forms the last element of the array of even number of radiating elements. Fig 7 shows one type of intermediate plate (type-1), which forms an element when affixed to end plate-1 Fig 8 shows another type of intermediate plate (type-2) Fig 9 shows the absorptive back plate fixed to the one end of the antenna element Fig 10 shows the coaxial connector assembly with field exciting probe and dielectric bush. DESCRIPTION OF THE PREFERRED EMBODIMENT WITH RESPECT TO THE DRAWINGS Referring to Fig. 1, Fig. 2 and Fig. 3, the high power linear phased array antenna of the present invention comprises a plurality of radiating elements (1) joined together through mechanical means such as nuts and bolts (2) These radiating elements are led input power through coaxial connectors (3) Referring to Fig. 4, Fig. 5 & Fig. 6, the high power linear phased array antenna of the present invention having n radiating elements will have n+l separate plates. The radiating element (1) of the present invention is made in double ridged waveguide type structure by integrating two metal plates (25) and (26) together, each having complimentary parts of the antenna machined on it. The next radiating element (1) will comprise plate (26) and plate (27) again joined together by mechanical means. As such, a high power linear phased array antenna having 22 radiating elements will have a total of 22 +1 =23 such plates. Each of the radiating elements (1) has three different sections of ridged wave-guide type structures fabricated together on the same conducting plate. The three sections are transitionIexcitation section, transmission line section and radiating section. Transition/excitation section consists of double ridged wave-guide cavity in which a suitably designed metal probe (14) is inserted through a hole (19) in one of the broad walls (7) of the wave-guide. The hole (19) is so made that it passes through one of the broad walls (7) of the wave-guide and through the ridges (8) and (9) inside the cavity and terminates at the inner side of the opposite broad wall (7). In this region the ridges (8) and (9) on the two opposing broad walls (7) of the wave -guide have a fixed gap between them. From the center of the hole (19), the ridge (8) height is reduced to a desired height towards the back wall (4). to provide a step for impedance matching. The ridges (8) on both the broad walls (7) of the wave guide extend up to a required length towards the back wail (4). The closed end back wall (4) of this transition section is made of machinable metal filled absorptive material (22) to provide impedance matching over relatively wide frequency band. Usually, the impedance matching in such coaxial to wave-guide transitions is achieved with the help of various tuning screws inserted inside the cavity region either through broad walls (7) or through back walls (4) of the wave-guide. However,, in .the present embodiment of the invention, this cumbersome technique has been avoided in favour of an easier approach. '. ! The RF energy from transition section is guided towards the radiating section by a 30 degree bent double-ridged transmission line section. The neighbouring radiating .elements of the array are given 30 degree bend in opposite direction to each other to stagger the feed input points in order to get enough space for connecting inter connecting plug type cable connectors used for connecting the array elements to high power RF source or beam forming networks. The ridges (9) in this section have uniform height throughout the length of transmission line section similar to the height at the open end of transition section, The guided radio frequency energy travels into the radiating section of the antenna element. In this section, the narrow walls (6) of the wave-guide is linearly flared out to a desired angle and over a desired length to provide an adequate transition region between ridged wave guide and the free space. The ridges (10). extending from transmission section into this section, are continuously tapered to a height of 0.1mm towards the open aperture end (12). The length of the tapered ridge (10) is 283.6 mm. The tapered ridge, together with flared sidewalls and the flat broad wall, forms a H-plane secforal horn. The horn face (12) in H-plane is made circular to reduce the phase error between radiating RF energy at the center and the radiating energy at the edge of the aperture. The dimension of the aperture in the E-plane is uniform over the entire length of the horn Each of the conducting plates (25) & (26), constituting the radiating elements (1), is constructed from a block of electrically conductive material such as aluminum and has an outer dimension of 360.2 mm (length), 172 mm (width) and 11.92 mm (thickness). The entire array has been constructed by adopting a modular approach. Further, two different types of end plates and two different types of intermediate plates are used for building the entire antenna array by simply stacking the conducting plates in required order. The back wall sub assembly and coaxial connector sub assembly are integrated with each radiating element. The conducting plate (25) and the other complimentary plate (26) are affixed together to form opposing wide surfaces (7) of a ridged waveguide structure, narrow wall portion (6) and open-end horn radiator The rear wall portion (4) is affixed so as to form the closed end of the waveguide and the affixed members form a tapered ridge rectangular waveguide H-plane sectoral horn antenna element. The ridge waveguide antenna elements are fed by special short height, high power coaxial connector (3) having a metal probe (14) passing through hole (19). Referring to Fig.7 and Fig 8, the ridges (8), (9) and (10) here having appropriate width are machined in each of three different sections on one side of each of the end plates (type 1 and type 2)i On the other side of each of these plates, a connector fixing slot (11) and a hole (19) for inserting the exciting metal probe (14) are machined. '. ' In the above two element plates of type-1 and type-2, the radiating H-plane sectoral horn extends straight along the axis of the antenna ( X direction in Fig.1) while the transmission line regions on the two sides of the same plate bend by 30 degrees from the axial direction in relatively opposite direction i along Y direction in Fig.1) of- each neighbouring elements to provide necessary staggering of feed input point . Antenna element plates of type-1 ana type-2, when stacked together, form the identically constructed antenna elements of the phased array. This stacking of elements is terminated (along Z direction in Fig 1) using two different end plates. Further, only on one side of the each of the end plate the complementary part of the end radiating elements are machined and the other side (18), (20) of it is left flat. Disposed along the boundary of the radiating elements (1) along X direction (leaving the back wall (4) and radiating aperture (12)). spigot (15) here of appropriate width and depth is provided on each complimentary part of the element (1). This spigot(15) reduces any chance of mutual coupling between the neighbouring elements due to leakage and coupling of RF energy along the junction. This spigot (15) also ensures that the ridges (8). (9). (10) and broad walls (7) on both the sides are in alignment or registration with each other. Eacn plate forming the members has holes (17) drilled through it into outer surface (16) of the plate for bolting the members together with tie rods and nuts (2). Referring to Fig. 9, the rear wall (4) has two parts; a metal filled absorptive block (22) fixed to a metallic plate (21) such as aluminum, with mechanical means. This assembly is then fixed with screws (5) at rear end of the transition section in such a way that the metal filled absorptive block (22) fills the inner part of the rear cavity and touches the ridge (8) end, the narrow walls (6) and broad walls (7) of the wave guide cavity. Referring to Fig. 10, each of the radiating element of the array antenna is excited with dimensionally "equal metal probe (14) connected to a especially developed right angled high power coaxial connector of relatively smaller height which fits into the inter element spacing of the array. The metal probe (14) is inserted in the wave-guide transition section to a fixed depth through the hole (19) provided in the broad wall (7) of the double-ridged wave-guide cavity The center conductor (23) of the coaxial connector (3) is insulated from the conducting wall of the element with the help of a dielectric bush (24) such as Teflon, which extends up to the thickness of broad wall (7) The coaxial connector (3) is electrically and mechanically connected to connector fixing slot (11) in the transition section. The inner conductor center pin (23) is separated from the walls of the hole (19.) by a dielectric spacer (24), which extends only up to the thickness of the broad walls (7). Radio frequency energy fed in this region via coaxial connector (3) thus launches radio frequency energy into cavity, which travel towards the open-end transmission line/section of the cavity in TE.sub.10 mode having electric field vector between the wide surfaces of the waveguide. The RF energy traveling towards the close encj is reflected back in the open-end direction and adds in phase with RF energy traveling in that direction. Further. the absorptive back wall (4) also absorbs some RF energy. All the radiating .elements (1) are machined to a tight tolerance of 50 micron to make it mechanically identical. These conditions provide a phase matching of ± 20 degree-and gain tracking of ± 2 dB for each of the radiating elements in the array over the desired frequency band. Each radiating element of the array when connected with suitable multi port beam forming networks having n inputs, n number of ccllimated beams of radio frequency energy can be formed in free space over 90 degree sector. The array was integrated with 15 beam ports and 16 array ports beam forming network. 15 beams were formed with scanning over 90 degree sectors. Here only 16 radiating elements were used with three elements on either side of the array terminated in matched load to provide array environment to the last radiating elements at both ends The array can be used for receiving as well as transmitting applications. When individual high power radio frequency sources, like traveling wave tubes are connected to each of the radiating element, especial combination of power takes place and this phased array antenna can radiate very high effective RF power. These properties from the array are possible over 7.5 - 18 GHz of frequency band. The present embodiment of the invention, which has been set forth above, was for the purpose of illustration and is not intended to limit the scope of the invention. It is to be understood that various changes, adaptations and modifications can be made in the invention described above by those skilled in the art without departing from the scope of the invention, which has been defined by following claims. I CLAIM; 1. A high power linear phased array angtenna comprising: m number of radiating elements (1) having (m+1) number of conducting plates stacked together with mechanical means, each radiating element (1) comprising a first conducting plate (25) integrated with a second conducting plate (26), said conducting plate (26) being the said first conducting plate of a succeeding radiating element and mechanically coupled with a third conducting plate (27), wherein, the mth radiating element comprising mth conducting plate of the (m-l)th radiating element mechanically coupled with the (m+l)th conducting plate of the said mth radiating element, where m is a positive integer and m 2; wherein, each of the said radiating element further comprises a closed end absorptive back wall (4) and a coaxial connector 93) for getting input power. 2. A high power linear phased array antenna as claimed in Claim 1 wherein each of the said radiating element is capable of handling 100 watt of continuous wave (cw) radio frequency energy fed through the said coaxial connectors (3) even at a higher frequency of 18 GHz. 3. A high power linear phased array antenna as claimed in Claim 1 wherein said coaxial connectors (3) are right angle type connectors. 4. A high power linear phased array antenna as claimed in Claim 1 wherein said absorptive back walls (4) are capable of providing impedance matching over a relatively wide band of frequency. 5. A high power linear phased array antenna as claimed in Claim 1 wherein additional number of radiating elements are stacked with mechanical means to reralise an antenna with higher number of radiating elements. 6. A high power linear phased array antenna as claimed in Claim 1 wherein the said radiating elements (1) have a double ridged wave guide structures with each of said conducting plates having complimentary parts of the said double ridged wave guide structure. 7. A high power linear phased array antenna as claimed in Claims 1 and 6 wherein said double ridged wave guide structure in the radiating elements has transition section, transmission line section and a radiating section. 8. A high power linear phased antenna as claimed in Claims 1 to 7 wherein said transmission line section comprises of ridged wave guide with smooth curve bend from the radial axis of the said antenna. 9. A high power linear phased array antenna as claimed in Claim 1 wherein said radiating elements (1) are sectoral horn type radiating elements. 10. A high power linear phased array antenna as claimed in Claim 1 wherein one side of the said first conducting plate of the said first radiating element has a flat surface. 11. A high power linear phased array antenna as claimed in Claim 1 wherein one side of the said (m+l)th conducting plate of the said mth radiating element has a flat surface. 12. A high power linear phased array antenna substantially as herein described and illustrated.

Documents:

136-DEL-2003-Abstract-(05-03-2008).pdf

136-del-2003-abstract.pdf

136-DEL-2003-Claims-(05-03-2008).pdf

136-del-2003-claims.pdf

136-del-2003-correspondence others.pdf

136-DEL-2003-Correspondence-Others-(05-03-2008).pdf

136-del-2003-correspondence-po.pdf

136-DEL-2003-Description (Complete)-(05-03-2008).pdf

136-del-2003-description (complete).pdf

136-del-2003-drawings.pdf

136-DEL-2003-Form-1-(18-02-2008).pdf

136-del-2003-form-1.pdf

136-del-2003-form-18.pdf

136-DEL-2003-Form-2-(05-03-2008).pdf

136-del-2003-form-2.pdf

136-DEL-2003-Form-3-(05-03-2008).pdf

136-del-2003-form-3.pdf

136-del-2003-gpa.pdf