Field of the Invention
This invention relates to antennas for wireless communications; and more particularly, to a circular polarized antenna with four isolated magnetic dipole elements disposed one adjacent to another about a square column substrate.
Description of the Related Art
A Square Quadrifilar Helical Antenna (S-QHA) is described in US 2010/0177014, published Jul. 15, 2010; hereinafter referred to as an “SQH Antenna”; the contents of which are hereby incorporated by reference.
The SQH Antenna provides a convenient manufactured device capable of receiving circular polarized signals for satellite communications. Manufacturing of the SQH Antenna is simple, and low-cost, which is a significant benefit in the industry. However, the SQH Antenna is not without complications, but instead is rather limited in terms of signaling efficiency and other performance characteristics.
It would be well received in the art to provide an improved antenna possessing the manufacturing benefits of the SQH Antenna, while enhancing performance characteristics associated with the antenna.
A circularly polarized isolated magnetic dipole (CP-IMD) antenna is described.
The CP-IMD antenna generally comprises: a first isolated magnetic dipole (IMD) element; a second IMD element positioned adjacent to the first IMD element; a third IMD element positioned adjacent to the second IMD element and configured to oppose the first IMD element; a fourth IMD element disposed positioned adjacent to each of the first and third IMD elements and configured to oppose the second IMD element; and a feed network configured to supply signals to the first thru fourth IMD elements at a phase difference of ninety degrees in a clockwise or counterclockwise direction.
Other features and advantages will be recognized by those with skill in the art upon a thorough review of the following descriptive examples and detailed embodiments.
In the following description, for purposes of explanation and not limitation, details and descriptions are set forth in order to provide a thorough understanding of the present invention in accordance with an illustrated embodiment. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments that depart from these details and descriptions without departing from the spirit and scope of the invention. An illustrated embodiment will be described below with reference to the drawings wherein illustrative features are denoted by reference numerals.
As used herein, the term “isolated magnetic dipole” (IMD) antenna element is generally a dipole conductor arranged with a portion of a first terminal end configured to overlap with a portion of a second terminal end thereof, forming a loop portion with a corresponding inductive reactance, and a capacitive region with a corresponding capacitive reactance, resulting in improved isolation of the antenna from nearby components. Examples of IMD elements can be referenced in commonly owned U.S. Pat. Nos. 7,084,813; 7,777,686; 8,421,702; and 7,932,869; the contents of each of which are hereby incorporated by reference.
Although the M-IMD element is illustrated, the invention may be practiced by incorporating any isolated magnetic dipole element in place of the M-type IMD element, or a combination of IMD elements.
The M-IMD can be tuned to vary a frequency response of the antenna by changing the distance of a gap between overlapping horizontal portions, or by elongating or reducing the amount or length overlap of horizontal portions. The idea is that more or less capacitance can be implemented between the horizontal portions for tuning the antenna element to a desired frequency.
Additionally, the size of ground can be used to vary the frequency response of the antenna in accordance with known methods.
Other IMD elements can be incorporated depending on the desired application.
With each of the IMD antennas tuned to a desired frequency, or multiple frequencies, one can produce four IMD antennas for incorporating into a circularly polarized isolated magnetic dipole assembly as described herein.
In general, a circularly polarized isolated magnetic dipole antenna (CP-IMD antenna) comprises a first isolated magnetic dipole (IMD) element; a second IMD element positioned adjacent to the first IMD element; a third IMD element positioned adjacent to the second IMD element and configured to oppose the first IMD element; and a fourth IMD element disposed positioned adjacent to each of the first and third IMD elements and configured to oppose the second IMD element; and a feed network configured to supply signals to the first thru fourth IMD elements at a phase difference of ninety degrees in a clockwise or counterclockwise direction.
The use of isolated magnetic dipole elements provides several benefits, including: each of the four adjacent IMD elements is disposed on one of four sides of the antenna, providing better isolation and improved manufacturing; and each of the IMD elements is inherently configured for improved isolation between adjacent elements. These benefits result in an improved antenna performance over prior art circularly polarized antennas.
In one embodiment, a CP-IMD antenna assembly is manufactured to comprise each of: a square column substrate extending from a bottom end to a top end thereof and having a first side through a fourth side each adjacently disposed about an external surface of the column; a first antenna plate comprising a planar substrate and a first isolated magnetic dipole (IMD) element disposed on at least one planar surface thereof, a second antenna plate, a third antenna plate, and a fourth antenna plate; each of the first through fourth antenna plates being separately disposed on one of said first thru fourth sides of the column; and four dielectric insulators each being disposed above one of the first thru fourth antenna plates and configured to cover the respective IMD elements; wherein each of the antenna plates is disposed between a respective side of the column and a corresponding dielectric insulator; and wherein the assembly is housed within a cylindrical cover. The antenna and manufacturing method are illustrated and described herein.
Each of the four antenna plates can comprise an IMD antenna element, the four IMD elements being positioned about the square column for providing enhanced isolation between adjacent elements.
Each of the four IMD elements, respectively, can be individually confined to a single side of the square substrate.
In another embodiment, the first and third IMD elements are each positioned on a first pair of opposing sides of the square column, and the first and third IMD elements are tuned to a first frequency. The second and fourth IMD elements are each positioned on a second pair of opposing sides of the square column, and the second and fourth IMD elements are tuned to a second frequency that is slightly distinguished from the first frequency. This results in improved isolation between the adjacent IMD elements and improves the radiation efficiency of the structure.
In another embodiment, the first through fourth IMD elements are each tuned to a slightly distinguished frequency. In this regard, the first IMD element is tuned to a first frequency, the second IMD element is tuned to a second frequency slightly higher than the first frequency, the third IMD element is tuned to a third frequency slightly higher than the second frequency, and the fourth IMD element is tuned to a fourth frequency slightly higher than the third frequency. Thus, the antenna comprises a slight increase in frequency from one element to the next around a perimeter of the antenna, resulting in an increase in return loss and/or axial ratio bandwidth.
In yet another embodiment, the antenna is configured to generate a dual resonance from each of the four IMD elements about the antenna for providing a dual frequency circular polarized antenna.
Now turning to the drawings, the CP-IMD antenna will be described with reference to a preferred embodiment as illustrated in
To further illustrate a preferred embodiment, the substrate 210 is further shown in
Covers are illustrated in
In the CP-IMD antenna, variations may be produced which have resulting distinct benefits. For example, in an embodiment, the first IMD element and third IMD element, which are configured to oppose one another, may be tuned to a first frequency using any of the methods discussed above. Similarly, the second and fourth IMD elements, which are also configured to oppose one another, may be tuned to a second frequency slightly distinct from the first frequency. In this embodiment, it becomes feasible to expand either or both the return loss bandwidth or axial ratio bandwidth.
In another variation, each of the first thru fourth adjacent elements can be tuned to a slightly distinct and increased frequency beginning with the first element thru the fourth element about the antenna. This embodiment has been shown to result in increased return loss and/or axial ratio bandwidth.
In yet another varied embodiment, each of the four respective IMD elements can be tuned to produce a dual frequency response. The resulting CP-IMD antenna will provide a dual-frequency circular polarization.
A particularly beneficial application for the CP-IMD antenna includes the global positioning system (GPS) application. GPS frequencies include at least: 1575 MHz; 1227 MHz; and 1381 MHz; however others can be implemented depending on the desired application. Although GPS is a useful application, it should be recognized that other frequencies, and multiple frequencies, can be tuned for use within the CP-IMD antenna.
In another embodiment, it is possible to use two CP-IMD antenna elements and place them opposite to each other on the first and third face of a square substrate. These elements can be used to generate circular polarization.
In another embodiment, it is possible to use two CP-IMD antenna elements that are placed adjacent to each other on either the first and second face or the first and fourth face of the square substrate and fed 90 degree out of phase to produce Right Hand or Left Hand Circular Polarization respectively.
This application claims benefit of priority with U.S. Provisional Ser. No. 61/955,165, filed Mar. 18, 2014, titled “CIRCULAR POLARIZED ISOLATED MAGNETIC DIPOLE ANTENNA”; the contents of which are hereby incorporated by reference.
Number | Name | Date | Kind |
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4479127 | Barbano | Oct 1984 | A |
4933680 | Shapiro | Jun 1990 | A |
5173711 | Takeuchi | Dec 1992 | A |
6486853 | Yoshinomoto | Nov 2002 | B2 |
6919859 | McCarthy | Jul 2005 | B2 |
8390526 | O'Connell | Mar 2013 | B1 |
20100177014 | Min | Jul 2010 | A1 |
Number | Date | Country | |
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20150311600 A1 | Oct 2015 | US |
Number | Date | Country | |
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61955165 | Mar 2014 | US |