Patent Application
20060227061
The present invention generally relates to antennas and, more specifically, to collinear antennas.
With advancements in technology, antennas have changed in size and range. One specific category of antenna that may be used to provide two-way communication is the omnidirectional collinear array. These antennas typically consist of multiple radiators placed end-to-end and fed in phase.
In order to counter the resulting mismatch and restore efficient radio frequency-power transfer, it is common practice to implement a tuned impedance-matching network between the feed point and the coaxial feedline. Unfortunately, this addition introduces higher manufacturing cost, greater structural complexity, reduced operating bandwidth, and increased radio frequency losses.
Also, in order to faithfully replicate resonant microwave circuitry, antennas of this type may be wholly or partially constructed as a printed circuit board (PCB) based strip line structure. PCB construction offers the advantage of accurate high-volume replication, but the liabilities of constructing radio frequency networks and radiators on a PCB are also well known. Specifically, two-dimensional strip line sleeves generally yield inferior common-mode rejection when compared to a fully surrounding cylindrical sleeve. More significantly, virtually any PCB substrate material one might select will introduce greater dielectric loss than a structure constructed in the dielectric medium of air. The amount of loss is usually related inversely to price. When a PCB substrate material with high dissipation losses, such as FR4, is introduced for the purpose of minimizing antenna cost, losses will be relatively high and may prove unacceptable. Conversely, when a low-dissipation material is used to control losses, the cost may prove prohibitive.
Thus, a heretofore unaddressed need exists in the industry to consider and address the aforementioned deficiencies and inadequacies.
Embodiments of the present invention provide a system and method for providing a collinear antenna.
Briefly described, in architecture, one embodiment of the system, among others, can be implemented as follows. An antenna includes a differential transmission line and a center conductor, where the center conductor is at least partially contained within the differential transmission line and at least partially protruding therefrom. A first conductive flat element is connected to the center conductor and a flat meander-line structure is integral with the first conductive flat element. In addition, a second conductive flat element is integral with the flat meander-line structure. The present invention can also be viewed as providing a method of assembling an antenna, the method comprising the steps of: forming a first conductive flat element, a meander-line structure, and a second conductive flat element, wherein the first conductive flat element and the second conductive flat element are connected by the meander-line structure; sliding a cylindrical dipole sleeve over a differential transmission line, wherein the differential transmission line has a center conductor therein, such that the center conductor at least partially protrudes from the differential transmission line and the cylindrical dipole sleeve; and connecting the center conductor to the first conductive flat element.
Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.
Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
The cylindrical dipole sleeve 116 may, for example, be formed at the end of the differential transmission line 124, where the differential transmission line 124 may be, for example, but not limited to, a standard 50-Ohm coaxial cable. The cylindrical dipole sleeve 116 may be formed from a crimp structure. Using a crimp structure may allow, for instance, faster, more efficient, and safer assembly methods than structures designed for soldering. Those having ordinary skill in the art may know of other methods and apparatus for making and assembling the cylindrical dipole sleeve 116 without deviating from the intent of the invention.
The first flat element 118, the flat meander-line structure 120, and the second flat element 122 are collectively referred to herein as the stamped component. The stamped component may be rigid in form. The stamped component may, for instance, be formed from a single low-cost thin-sheet conductive metal to minimize costs. In addition, the stamped component may be formed by a precision stamping process instead of photo-etching. Precision stamping provides tighter control over dimensional tolerances as well as greater dimensional stability and higher repeatability. The unified stamped component may be self-supporting in the dielectric medium of air.
Form factor for the first flat element 118 and second flat element 122 may be determined by Euclidean methodology, predictive computer modeling, or through advanced GA-based modeling techniques, or any other method, so as to optimize the antenna for impedance match and bandwidth.
The first flat element 118 provides one leg of a sleeve dipole launch element for the collinear antenna 110. Prospective variations in the configuration of this first flat element 118 are shown in
The flat meander-line phasing structure 120 may be formed between the first flat element 118 and the second flat element 122 as an integrated part of the monolithic structure so as to eliminate the need for an externally appended network requiring mechanical and electrical bonding. Eliminating this need permits a single direct connection from the center conductor 112 of the differential transmission line 124 to the first flat element 118, while maintaining functionality of the antenna 110. As is shown by
The second flat element 122 may also exhibit one of many different shapes. As an example,
The first flat element 218 is shaped strategically and formed with slots 228 for the purpose of enhancing bandwidth and improving impedance match. This first flat element 218 is separated from the cylindrical dipole sleeve 216 by a space 226. A flat meander-line structure 220 is integral with the first flat element 218. A second flat element 222 is integral with a far end of the flat meander-line structure 220. The second flat element 222 is also shaped to work in conjunction with the first flat element 218 to provide an improved impedance match with an impedance of the differential transmission line 224. The design of the second exemplary embodiment, shown in
The first flat element 218, the flat meander-line structure 220, and the second flat element 222 are collectively referred to herein as the stamped component, as in the first collinear antenna 110 of the first exemplary embodiment of the invention.
The flow chart of
As shown in
Assembling the collinear antenna 110 may also include leaving a space 126 between the cylindrical dipole sleeve 116 and the first conductive flat element 118. The first conductive flat element 118, the meander-line structure 120, and the second conductive flat element 122 may be formed from a single piece of metal. The first flat element 118, the meander-line structure 120, and the second flat element 122 may be formed from multiple pieces of metal, other conductive materials, and bonded together. The first flat element 118, the meander-line structure 120, and the second flat element 122 may be supported in a dielectric medium of air, although supporting the stamped components on a substrate is also contemplated. The first flat element 118 may have slots and/or a solder-style V crimp formed therein.
Assembling the collinear antenna 110 may also include inserting an at least partially stripped coaxial cable (i.e., the differential transmission line 124) in a cable clamp such that the center conductor 112 in the coaxial cable at least partially protrudes from the cable clamp. A crimp sleeve can then be crimped over the coaxial cable to hold in place a cable shield of the coaxial cable. The cylindrical dipole sleeve 116 may then be crimped into place. These connections may similarly be made with solder style connections replacing some or all of the crimping connections.
It should be emphasized that the above-described embodiments of the present invention are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiments of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.
