The disclosure relates in general to an antenna, and more particularly, to a proximity hybrid antenna array.
Numerous systems, especially handheld and portable systems, utilize different types of antennas in close proximity to each other. Close proximity, as used herein, refers to at least two antennas being within their frequency-dependent near-field range (e.g., “coupled” to those skilled in the art of antenna design), up to and including physical contact which includes capacitive high-frequency contact (e.g., “tightly coupled” or “AC coupled”), and which can even include Ohmic contact (e.g., “DC coupled”). The close proximity of multiple antennas can lead to undesired interactions between them, which can result in de-tuning of a frequency of resonance and/or unacceptable operation of antennas, which result in formation of nulls within one or more antennas' operating bands, and/or redirection of the radiation pattern (e.g., “beam-steering”) of one or more antennas.
The disclosure is directed to a system that includes a first antenna and a second antenna. The first antenna includes an antenna section. The antenna section includes a first antenna segment, a second antenna segment adjacent to the first antenna segment, and a notch circuit disposed within a notch between the first antenna segment and the second antenna segment. The notch circuit prevents a first frequency of a signal from passing from the first antenna segment to the second antenna segment while allowing a second frequency from the signal to pass from the first antenna segment to the second antenna segment. The second antenna is disposed proximate to the first antenna. The first antenna occupies a second near field region of the second antenna and the second antenna occupies a first near field region of the first antenna.
In some configurations, the first antenna is a Quasi-Yagi Ultra High Frequency (UHF) antenna and the second antenna is a nested coaxial helical antenna.
In some configurations, the notch circuit includes a capacitor in parallel with an inductor.
In some configurations, the notch circuit is a first notch circuit and the antenna section includes a third antenna section disposed between the first antenna section and the second antenna section, the first notch circuit including a first capacitor disposed between the first antenna segment and the third antenna segment and the second notch circuit is disposed between the third antenna segment and the second antenna segment, the second notch circuit including a second capacitor in parallel with an inductor.
In some configurations, the antenna section is a first antenna section, the system further including a second antenna section coupled to the first antenna section, the first antenna section preventing a first frequency range from passing to the second antenna section and the second antenna section preventing a second frequency range, the first frequency range different than the second frequency range, from passing beyond the second antenna section.
In some configurations, the system further includes a reflector element that includes the antenna section.
In some configurations, the system further includes a radiator element that includes the antenna section.
In some configurations, the system further includes a director element that includes the antenna section.
In some configurations, the system further includes a reflector element, a radiator element, and a director element, each of the reflector element, the radiator element, and the director element including the antenna section.
In some configurations, the system further includes a Printed Circuit Board (PCB), the first antenna being printed onto the PCB.
In some configurations, the system further includes a ground plane that electrically couples together the first and second antennas.
In some configurations, the second antenna includes a primary outer helix and an inner helix, the ground plane also coupling the primary outer helix and the inner helix together.
The disclosure will now be described with reference to the drawings wherein:
While this disclosure is susceptible of embodiment(s) in many different forms, there is shown in the drawings and described herein in detail a specific embodiment(s) with the understanding that the present disclosure is to be considered as an exemplification and is not intended to be limited to the embodiment(s) illustrated.
It will be understood that like or analogous elements and/or components, referred to herein, may be identified throughout the drawings by like reference characters. In addition, it will be understood that the drawings are merely schematic representations of the invention, and some of the components may have been distorted from actual scale for purposes of pictorial clarity.
In accordance with the embodiment(s) disclosed herein, one or more of a lower frequency first antenna's element(s) is segmented into small sections separated by band-stop circuitry, referred to herein as a notch circuit(s). The notch circuit(s) performs filtering in that the notch circuit(s) prevents signals of a higher frequency second antenna from achieving a resonant condition on original elements of a first antenna, which then renders the first antenna unable to support the transmission, reflection, or radiation of the higher frequency band-stop bands. Because the segments are typically too short in length to adversely affect specific frequencies of interest, they have a reduced impact on antenna performance.
As discussed in more detail below, the first antenna gets segmented, and in at least one embodiment, shortening in length and other physical and/or electrical characteristics to compensate for the addition of the notch circuit(s). The effect on the segmented antenna is typically a size reduction that ensures an aperture size-related reduction in gain, as well as a decrease in efficiency due to the higher losses in band-stop components compared to a typical radiating structure. The reduced efficiency results in a further reduction in realized gain of the segmented antenna beyond that associated with the reduction in aperture size.
High impedance resonant circuitry, or notch circuitry, are used with one or more element(s) of the first antenna, such as a lower-frequency antenna structure. These resonant circuit(s) serve as band stops for the frequency bands used by a second antenna, such as a higher frequency antenna, in close proximity to the first antenna. The band stops are sufficiently close together that the lengths of continuous low-impedance paths are significantly shorter than a half wavelength of the frequencies used by the second antenna. These aspects are arranged to result in a reduction in interference of the second antenna by the proximity of the first antenna.
Referring now to the drawings and in particular to
In at least one embodiment, the second antenna 120 includes a primary outer helix 122 and an inner helix 124. The outer helix 122 has a circular polarization and can operating between 2400 and 2500 MHz. The inner helix 124 has an opposing circular polarization and can operate between 5700 and 5900 MHz. A ground plane 130 electrically couples the first and second antennas 110/120 together and couples the outer and inner helixes 122/124 together. In at least one embodiment, a diameter of the outer helix 122 is approximately (+=10%) 3.9 cm, with spacing between each coil thereof approximately (+=10%) 3.1 cm. In at least one embodiment, a diameter of the inner helix 124 is approximately (+=10%) 1.6 cm, with spacing between each coil thereof approximately (+=10%) 1.3 cm.
With reference to
The single notch circuit 230 is a resonant circuit that has at least one narrowband predominantly reactive (as opposed to resistive) element, having very low series equivalent resistance and a high-quality factor Q. In at least one embodiment as shown in
With reference to
The dual notch circuit 330 is a resonant circuit having very low series equivalent resistance and a high-quality factor Q. In at least one embodiment as shown in
In at least one embodiment, the antenna segments 410a/410b/410d/410e/410g/410h/410j/410k can range between approximately (+−10%) 0.290 and approximately (+−10%) 0.370 inches and the segments 410c/410f/410i can be approximately (+−10%) 0.080 inches. The director element 400 can include a plurality of notch circuits, such as single high-frequency notch circuits 430a/430b/430c/430d that each correspond to the single notch circuit 230 and dual notch circuits 450a/450b/450c that each correspond to the dual notch circuit 330. The director element 400 includes an arrangement of notch circuits, from left to right, such as the single notch circuit 430a, a dual notch circuit 450a, another single notch circuit 430b, another dual notch circuit 450b, another single notch circuit 430c, another dual notch circuit 450c, and another single notch circuit 430d. In at least one embodiment, the length of the director element 400 is approximately (+=10%) 2.97 inches, an appropriate length for enhancing directivity of approximately (+=10%) 856 to 1300 MHz signals, as known to those skilled in the art of Quasi-Yagi antenna design.
The alternating pattern of the single notch circuits 430a/430b/430c/430d and the dual notch circuits 450a/450b/450c results in the director element 400 rejecting passage of 5.7 to 5.9 GHz energy, but only each pair of single and dual notch circuits reject passage of 2.4 to 2.5 GHz energy. In at least one embodiment, length of antenna segments between two neighboring single high frequency notch circuits 430a/430b/430c/430d can be between approximately (+−10%) 0.290 and approximately (+−10%) 0.370 inches, corresponding to approximately (+−10%) 60 degrees of antenna segment length at 5.9 GHz. Counting an initial feed length into the inductor elements prior to the notch rejection, this can result in approximately (+−10%) 65-70 degrees of antenna segment length at 5.9 GHz, to those skilled in the art of RF filter design. This short line length is insufficient to sustain a standing wave, and therefore is largely ignored (other than as a mild scattering obstacle) by frequencies in that range.
For a lower band, the dual notch circuits 450a/450b/450c are disposed approximately (+−10%) every 0.770 inches of printed circuit length, corresponding also to approximately (+−10%) 60 degrees of line length at 2.44 GHz midband. Counting the initial feed length as discussed above, this can result in approximately (+−10%) 65-70 degrees total between the dual notches 450a/450b/450c. As with the higher band, this line length is insufficient to sustain a standing wave between 2.4 and 2.5 GHz, so the entire construct of the director element 400 performs as a patterned mild scattering obstacle rather than a reflecting, radiating, or parasitic element.
In at least one embodiment, the first antenna 110 is a Quasi-Yagi antenna that includes a radiator element 520, a reflector element 510, and at least two director elements, such as director elements 530/540/550/560. With reference to
In at least one embodiment, the reflector element 510 includes eight (8) single notch circuits 511a/511b/511c/511d/511e/511f/511g/511h (e.g., each including 1.2 nH, 0.6 pF), with dual notch circuits 512a/512b/512c/512d/512e/512f/512g (e.g., each including 9 pF, 2.2 nH, 1.8 pF) disposed therebetween. In at least one embodiment, the radiator element 520 includes four (4) sub-elements 520a/520b/520c/520d all coupled to a wire jack 570, such as an MMCX jack. The radiating sub-elements 520a and 520b each include three (3) single notch circuits 521a/521b/521c/521d/521e/521f (e.g., each including 0.6 pF, 1.2 pF) alternating with three (3) dual notch circuits 522a/522b/522c/522e/522f (e.g., each including 9 pF, 2.2 nH, 1.8 pF) coupled thereto, respectively, as shown. The radiating sub-elements 520c and 520d each include two (2) single notch circuits 521g/521h/521i/521j (e.g., each including 0.6 pF, 1.2 pF) alternating with (2) dual notch circuits 522g/522h/522i/522j (e.g., each including 9 pF, 2.2 nH, 1.8 pF) coupled thereto, respectively, as shown.
In at least one embodiment, the antenna system 500 further includes the four (4) director elements 530/540/550/560. In at least one embodiment, the director elements 530/540/550/560 can all be disposed on a same side of the radiator element 520, as shown. In at least one embodiment, the director elements 530/540/550/560 can each be identically configured with a same number of alternating dual notch circuits, e.g., five (5) dual notch circuits (e.g., each including 9 pF, 2.2 nH, 1.8 pF), and single notch circuits, e.g., four (4) single notch circuits (e.g., each including 1.2 nH, 0.6 pF), with antenna sections therebetween, as discussed above. In at least one embodiment, other configurations for the director elements 530/540/550/560 are possible, without departing from the scope of the embodiment(s) disclosed. The director element 530 can include alternating dual notch circuits, e.g., five (5) dual notch circuits 532a/532b/532c/532d/532e, and single notch circuits, e.g., four (4) single notch circuits 531a/531b/531c/531d, with antenna sections therebetween, as discussed above. Likewise, director element 540 can include alternating dual notch circuits, e.g., five (5) dual notch circuits 542a/542b/542c/542d/542e, and single notch circuits, e.g., four (4) single notch circuits 541a/541b/541c/541d, with antenna sections therebetween, as discussed above. Likewise, director element 550 can include alternating dual notch circuits, e.g., five (5) dual notch circuits 552a/552b/552c/552d/552e, and single notch circuits, e.g., four (4) single notch circuits 551a/551b/551c/551d, with antenna sections therebetween, as discussed above. Likewise, director element 560 can include alternating dual notch circuits, e.g., five (5) dual notch circuits 562a/562b/562c/562d/562e, and single notch circuits, e.g., four (4) single notch circuits 561a/561b/561c/561d, with antenna sections therebetween, as discussed above.
In at least one embodiment, the reactive elements of the capacitors and the inductors of the single notch circuit 230 and the dual notch circuit 330 can be printed as part of a circuit trace 610, as shown. The values of capacitance (e.g., 0.6, 1.8, and 9 pF) discussed above and inductance (e.g., 1.2 and 2.2 nH) discussed above used for the 2.4 and 5.8 GHz examples are readily achieved as multilayered integrated passives in PCB fabrication processes. One skilled in the art will understand that such values are exemplary, with such values being selected for a particular implementation's frequency needs. Such PCB fabrication processes reduce manufacturing cost and substantially reduces assembly time.
Given a pad size area A, substrate thickness d, and dielectric constant εr, the return capacitive coupling C can be estimated using conventional parallel-plate capacitor equations by those familiar with basic electrical engineering principals.
A calculation (not shown for the sake of brevity) estimates overlap pads made as integrated passives in a 4-layer board using foil laminated over e.g., pre-preg Isola FR-408, would be approximately (+=10%) 1 mm square yielding 0.6 pF in a more cost and size efficient manner than using a chip capacitor. The 9 pF capacitance, conversely, can be addressed as a chip capacitor.
The foregoing description merely explains and illustrates the disclosure and the disclosure is not limited thereto except insofar as the appended claims are so limited, as those skilled in the art who have the disclosure before them will be able to make modifications without departing from the scope of the disclosure.
The present application is a continuation of U.S. patent application Ser. No. 16/810,776 filed on Mar. 5, 2020, entitled “Filtering Proximity Antenna Array”, the entire specification of which is hereby incorporated by reference in its entirety.
Number | Name | Date | Kind |
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20110063187 | Huang | Mar 2011 | A1 |
20110215984 | Coburn | Sep 2011 | A1 |
20180090829 | McMichael | Mar 2018 | A1 |
20180287244 | Sharawi | Oct 2018 | A1 |
Number | Date | Country | |
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20230006359 A1 | Jan 2023 | US |
Number | Date | Country | |
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Parent | 16810776 | Mar 2020 | US |
Child | 17746837 | US |