Patent Application
20100134371
The field of the disclosure relates to broadband planar antennas.
It is often advantageous for antennas to be able to perform various functions over a broad frequency spectrum. Some of the current antennas use a federated approach to cover a large bandwidth at lower frequencies. Issues that may arise when trying to cover these lower frequencies are size, weight, mounting, and aero concerns, especially for large planar cavity-backed or protruding antennas (e.g. blades, dishes . . . ). Some developing ASW/ISR platforms simply cannot bear the additional drag counts that a typical and widely used blade antenna may incur or suffer the structural changes that a cavity-backed antenna would require. It has long been known that for narrow band antennas, when the antenna is placed near a conducting backplane the spacing between the antenna and the backplane must be designed at a specific electrical distance based on the antenna's operating frequency. This technique is used today in many different types of designs yet it almost always implies a narrow band structure. It has been shown in theory and practice that certain classes of frequency independent antennas can be placed above complex geometry conducting backplanes to maintain the antenna's broad-band response. However, these types of antennas are generally large, and difficult to build because the largest distance that they have to be from the backplane is on the order of a quarter wavelength at the lowest operating frequency.
A broadband antenna and/or method of manufacturing is needed to decrease one or more problems associated with one or more of the existing broadband antennas.
In one embodiment, a broadband antenna is provided. The broadband antenna may include: a conductive antenna surface for radiating signals; a conductive backplane for reflecting signals radiated by the conductive antenna surface; and a dielectric layer disposed between the conductive antenna surface and the conductive backplane. The dielectric layer may comprise a plurality of dielectric substrates having differing dielectric constants.
In another embodiment, a method of manufacturing a broadband antenna is disclosed. In one step, a conductive antenna surface may be provided. In another step, a conductive backplane may be provided. In an additional step, a dielectric layer, comprising a plurality of dielectric substrates having differing dielectric constants, may be disposed between the conductive antenna surface and the conductive backplane.
In yet another embodiment, a method of manufacturing a broadband antenna is disclosed. In one step, a lowest required operating frequency of the broadband antenna is determined. In another step, a highest required operating frequency of the broadband antenna is determined. In an additional step, a uniform thickness for an entire dielectric layer at a specified electrical distance is calculated at the lowest required operating frequency based on a dielectric material to be used in the dielectric layer having a highest dielectric constant. In still another step, the lowest required dielectric constant of the dielectric layer is calculated based on the calculated uniform thickness of the dielectric layer at the specified electrical distance to generate the specified electrical distance at the highest required operating frequency. In yet another step, the number of different dielectric materials to be used in the dielectric layer having differing dielectric constants between the lowest required dielectric constant and the highest dielectric constant is calculated based on a total bandwidth of the broadband antenna. In an additional step, widths of each of the respective differing dielectric materials to be used in the dielectric layer are calculated. In another step, the dielectric layer is fabricated using the calculations and determinations made in all steps of the method. In still another step, the dielectric layer is disposed against a conducting backplane. In another step, an antenna is disposed against the dielectric layer.
These and other features, aspects and advantages of the disclosure will become better understood with reference to the following drawings, description and claims.
The following detailed description is of the best currently contemplated modes of carrying out the disclosure. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the disclosure, since the scope of the disclosure is best defined by the appended claims.
A dielectric layer 122 may be disposed between and/or against the conductive surfaces 112 and 114 using a direct write process 149 and/or other type or process. The dielectric layer 122 may be flat and planar. In other embodiments, the dielectric layer 122 may be non-planar and/or in varying shapes. The dielectric layer 122 may comprise a plurality of dielectric substrates 122s1-122s15 having differing dielectric constants 122c1-122c15. The respective dielectric substrates 122s1-122s15 may have gradually larger (increasing) respective dielectric constants 122c1-122c15 along direction 121 from the dielectric substrate 122s1 with the lowest dielectric constant 122c1 to the dielectric substrate 122s15 with the highest dielectric constant 122c15. The electrical distance 118 between the conductive surfaces 112 and 114 may vary substantially identically along direction 121 as, in the conventional apparatus of
The end 114a of conductive surface 114 may be disposed at a substantially identical electrical distance 118a away from conductive surface 112 as, in the conventional apparatus 10 of
The broadband Archimedean spiral antenna 428 may comprise a conductive antenna surface 430 disposed apart in parallel relation from a conductive backplane 446. The conductive antenna surface 430 and/or conductive backplane 446 may be flat, may be planar, and/or may be a part of a ship, an airplane, a satellite, a spacecraft, a vehicle, and/or another type of structure. In other embodiments, the conductive antenna surface 430 and/or conductive backplane 446 may be non-planar and/or in varying shapes. The conductive antenna surface 430 may radiate signals 447, such as radio frequency signals and/or other types of signals, and the conductive backplane 446 may reflect the radiated signals 447.
A dielectric layer 448 may be disposed using a direct-write process 449 and/or other type of process against and/or between the conductive antenna surface 430 and the conductive backplane 446. The dielectric layer 448 may be flat and planar. In other embodiments, the dielectric layer may be non-planar and/or in varying shapes. The dielectric layer 448 may comprise a plurality of dielectric substrates 450s1-450s15 having differing dielectric constants 452c1-452c15. The dielectric substrates 450s1-450s15 may comprise concentric rings of varying dielectrics in between the conductive antenna surface 430 and the conductive backplane 446. This may allow a quarter-wavelength back-short to be disposed beneath each frequency of operation in order to emulate a conical ground plane.
The dielectric substrates 450s1 and 450s15 at the outer portions 448a and 448b of the dielectric layer 448 may have the highest dielectric constants 452c1 and 452c15 in order to provide the largest respective electrical distances 440a and 440b between the conductive antenna surface 430 and the conductive backplane 446. At a middle portion 448c of the dielectric layer 448, the dielectric substrate 450s8 may have the lowest dielectric constant 452c8 in order to provide the smallest respective electrical distance 440c between the conductive antenna surface 430 and the conductive backplane 446. Along direction 442 between the outer portion 448a and the middle portion 448c, the electrical distance 440 between the conductive antenna surface 430 and the backplane 446 may gradually decrease. Similarly, along direction 444 between the outer portion 448b and the middle portion 448c, the electrical distance 440 between the conductive antenna surface 430 and the backplane 446 may gradually decrease. Due to the varying dielectric substrates 450s1-450s15, the varying electrical distances 440 between the conductive antenna surface 430 and the conductive backplane 446 may be substantially identical at all respective locations along the dielectric layer 448 as the varying electrical distances 240 between the conductive antenna surface 230 and the ground plane 236 of the conventional Archimedean spiral antenna 228 of
The Archimedean spiral antenna 428 of
The lower frequency of operation in the Archimedean spiral antenna 428 may be set by the dielectric substrate 450s1 and 450s15 that have the maximum dielectric constant 452c1 and 452c15 and the desired electrical distance 440. Using these two values, the theoretical lower-bound of the antenna's operating band may be calculated. The upper end of the band may be similarly limited by the chosen electrical distance 440 and the dielectric substrate 450s8 having the lowest dielectric constant 452c8.
The Archimedean spiral antenna 428 of
In other embodiments, the disclosure may be applied to varying types of antennas having varying geometries with spatially separated radiation points for each frequency of operation throughout their operating bands. This characteristic may allow the use of a quarter-wavelength conductive backplane spacing beneath each frequency's specific point of radiation. The varying types of antennas the disclosure may be applied to may provide for reduced size, reduced return loss, and/or a lower voltage standing wave ratio than varying types of antennas having similar functions at similar frequencies that do not have a plurality of dielectric substrates having differing dielectric constants.
In step 572, a conductive antenna surface 430 may be provided. In step 574, a conductive backplane 446 may be provided. The provided conductive backplane 446 may comprise a portion of a structure 411 comprising a ship, an airplane, a satellite, a spacecraft, a vehicle, and/or another type of structure. In step 576, a dielectric layer 448 may be disposed between and/or against the conductive antenna surface 430 and the conductive backplane 446 using a direct write process 449 and/or another type of process. The disposed dielectric layer 448 may comprise a plurality of dielectric substrates 450s1-450s15 having differing dielectric constants 452c1-452c15. The disposed dielectric substrates 450s1 and 450s15 with higher dielectric constants 452c1 and 452c15 may provide higher electrical distances 440a and 440b between an adjacent portion of the provided conductive antenna surface 430 and an adjacent portion of the adjoining provided conductive backplane 446, while the disposed dielectric substrate 450s8 with the lowest dielectric constant 452c8 may provide a lower electrical distance 440c between an adjacent portion of the provided conductive antenna surface 430 and an adjacent portion of the provided conductive backplane 446.
One or more of the provided conductive antenna surface 430, the provided conductive backplane 446, and the displosed dielectric layer 448 may be flat and planar. In other embodiments, one or more of the provided conductive antenna surface 430, the provided conductive backplane 446, and the displosed dielectric layer 448 may be non-planar and/or in varying shapes. The resulting manufactured broadband antenna 428 may be planar, may have a small distance 441 between the provided conductive antenna surface 430 and the provided conductive backplane 446, may have a bandwidth greater than an octave, and/or may not have a cavity backing. In another embodiment, the resulting manufactured broadband antenna 428 may comprise: a spiral antenna 428; the disposed dielectric layer 448 may comprise concentric rings of varying dielectric substrates 450s1-450s15; and a middle portion 448c of the disposed dielectric layer 448 may comprise at least one dielectric substrate 450s8 with a lower dielectric constant 452c8 than dielectric constants 452c1 and 452c15 of dielectric substrates 450s1 and 450s15 at outer portions 448a and 448b of the disposed dielectric layer 448. In additional embodiments, the resulting manufactured broadband antenna 428 may comprise different shapes, configurations, sizes, and/or may have varying bandwidths.
In step 578, the provided conductive antenna surface 430 may radiate signals 447 such as radio frequency signals and/or other types of signals. In step 580, the provided conductive backplane 446 may reflect the radiated signals 447. In step 582, the manufactured broadband antenna 428 may perform a plurality of functions F over a broad frequency spectrum F1. In step 584, the manufactured broadband antenna 428 may provide a voltage standing wave ratio which is less than two at high frequencies. In other embodiments, the manufactured broadband antenna 428 may provide varying voltage standing wave ratios at varying frequencies. The manufactured broadband antenna 428 may have a reduced size, a reduced return loss, and/or a lower voltage standing wave ratio than antennas having similar functions at similar frequencies that do not have a plurality of dielectric substrates having differing dielectric constants.
In step 691, the number of different dielectric materials to be used in the dielectric layer 122, having differing dielectric constants between the lowest required dielectric constant of step 690 and the highest dielectric constant of step 689, may be calculated based on the total bandwidth of the antenna 428. Fifteen different dielectric materials per octave in the dielectric layer 122 may provide sufficient performance. A smooth gradient is possible. In other embodiments, differing numbers of dielectric materials may be used in the dielectric layer 122. In step 692, the widths of each of the respective different dielectric materials to be used in the dielectric layer 122, as determined in step 691, may be calculated. The widths may comprise the respective distances along each dielectric material which will be disposed directly against a conducting backplane and antenna. These calculations may be done using simulation software or other systems or methods. The widths may be chosen to closely emulate the slope of a physically tapered backplane. In step 693, the dielectric layer 122 may be fabricated using the calculations and determinations made in steps 687-692. In step 694, the dielectric layer 122 may be disposed against a conducting backplane 114. This may be done using a direct-write process, or other type of process. In step 695, an antenna 112 may be disposed against the dielectric layer 122. In other embodiments, one or more of the steps of the method 686 may be varied, deleted, and/or one or more other additional steps may be utilized.
It should be understood, of course, that the foregoing relates to exemplary embodiments of the disclosure and that modifications may be made without departing from the spirit and scope of the disclosure as set forth in the following claims.
