The present disclosure is generally related to antenna elements that are adapted to radiate signals in a wide pattern.
Selection of an antenna to use for a mobile platform, such as an aircraft, may involve tradeoffs between countervailing considerations. For example, there may be a tradeoff between various transmission or reception concerns and other countervailing considerations, such as aerodynamic profile. To illustrate, a conventional phased array antenna may have a limited scan angle, e.g. up to an angle of about 65° from a vertical axis toward a horizon. However, phased array antennas provide a small aerodynamic profile that result in little or no additional drag on the mobile platform. In contrast, a dish antenna may provide a wider scanning pattern, but may incur a significant aerodynamic profile penalty that results in higher drag on the mobile platform. Other tradeoffs may be considered with other types of antennas. For example, continuous transverse stub array antennas may provide a wide scanning range with a relatively small aerodynamic profile. However, continuous transverse stub array antennas tend to scan at relatively low speeds, which may not be suitable for applications where high scanning speed is desired.
In addition, different communications applications executing on the mobile platform may benefit from different antenna profile types. However, providing multiple antennas may add complexity, cost, bulk, weight, or some combination of these undesirable attributes to the mobile platform.
Embodiments disclosed herein include antenna elements that are operable to radiate signals in desired patterns over a wide area. When an antenna element is mounted relative to a surface, the antenna element is operable to radiate a signal through a range extending from a first direction perpendicular to the surface through a second direction parallel with the surface. The antenna element includes a plurality of radiating elements. A radiating element may include two connected conductive members that may be disposed within a non-conductive member. In the presence of other radiating members, the radiating element generates a radiation pattern that includes a null. The position of the null can be controlled. For example, by controlling phases of a supplying signal to two or more radiating elements, the location of the null of each of the radiating elements can be adjusted. Thus, the antenna element may radiate in a pattern similar to an open-ended waveguide, in a patter similar to a dipole antenna, or as another type of antenna.
In a particular embodiment, an apparatus includes a first antenna element having a plurality of radiating elements. Each of the plurality of radiating elements includes a first elongated member having a first end and a second end. The first end is coupled to an antenna interface and the second end extends a length of the first elongated member from the first end. A second elongated member has a third end and a fourth end. The third end is electrically coupled to the first elongated member at a point partway along the length of the first elongated member. The fourth end extends away from the first elongated member. When a first radiating element of the plurality of radiating elements is radiating in the presence of a second radiating element of the plurality of radiating elements, a null is generated in a radiation pattern of the first radiating element.
In another particular embodiment, an apparatus includes an antenna element that includes a non-conductive body and a plurality of radiating elements supported within the non-conductive body. Each of the plurality of radiating elements includes a first conductor extending to a conductor end at a distance of approximately λ/2 above an antenna interface, where λ is the wavelength of a signal intended to be transmitted via the antenna element. Each of the plurality of radiating elements also includes a second conductor electrically coupled to the first conductor at a distance of approximately λ/4 above the antenna interface. The second conductor extends substantially transversely from the first conductor. The plurality of radiating elements is arranged such that the second conductor of each of the plurality of radiating elements extends generally toward an adjacent radiating element.
In still another embodiment, a method includes receiving a signal at each of a plurality of radiating elements of an antenna element. Each of the radiating elements includes a first conductor having a first end and a second end. The first end is coupled to an antenna interface. The second end extends a length of the first conductor from the first end. A second conductor has a third end and a fourth end. The third end is electrically coupled to the first conductor at a point partway along the length of the first conductor. The fourth end extends away from the first conductor. The method also includes propagating the signal via the plurality of radiating elements. The signal is propagated in a first mode when the signal received by each of the plurality of radiating elements is at a same magnitude and in a common phase. The signal is propagated in a second mode when the signal received by each of the plurality of radiating elements is in the same magnitude and at a shifted phase with respect to an adjacent radiating element.
The features, functions, and advantages that are described can be achieved independently in various embodiments or may be combined in yet other embodiments, further details of which are disclosed with reference to the following description and drawings.
According to an illustrative embodiment, an antenna element is provided that may be used in a phased array to radiate signals in desired patterns over a wide area. The antenna element may be mounted over a surface and configured to radiate a signal through a range extending from a first direction perpendicular to the surface through a second direction parallel with the surface. The antenna element includes a plurality of radiating elements. When radiating in the presence of one or more other radiating members, each of the radiating elements generates a radiation pattern having a null. The null generated by each radiating member may be controlled to adjust a radiation pattern of the antenna element or of a phased array antenna that includes the antenna element. For example, by controlling a relative phase of a signal supplied to each of the radiating elements, the radiation pattern generated by the antenna element may be varied from a radiation pattern similar to an open-ended waveguide to a radiation pattern similar to a dipole antenna.
The second member 120 has a first end (designated as a third end 121 for eased of differentiation from the first end 111 of the first member 110) and a second end (designated as a fourth end 122 for eased of differentiation from the second end 112 of the first member 110). The second member 120 may be coupled, physically and electrically, to the first member 110 at a coupling point 130 partway along the first length 132 of the first member 110. In a particular embodiment, the coupling point 130 is approximately halfway along the first length 132. Thus, for example, where the first length 132 is approximately of λ/2, the coupling point 130 is at a distance 134 of approximately λ/4 from the first end 111 of the first member 110 and at a distance 136 of approximately λ/4 from the second end 112 of the first member 110. However, the distance 136, the distance 134, or both, may be adjusted during design of the radiating element to tune radiative properties of the radiating element 100.
As further described below with reference to
In a particular embodiment, the second member 120 has a second length 138 that is about one-half of the first length 132, e.g., approximately λ/4. The second member 120 may extend at an angle away from the first member 110. For example, the second member 120 may be approximately perpendicularly to the first member 110. To illustrate, the first member 110 may extend along the z-axis 106 and the second member 120 may extend in a plane defined by the x-axis 102 and the y-axis 104. The coordinate labels are assigned merely as a convenience to provide a reference system to facilitate the description. Thus, for example, in some embodiments, the first member 110 and the second member 120 may not be perpendicular to one another. However, the coordinate labels are used with other drawings disclosed herein to assist with understanding possible configurations of the disclosed embodiments. Also for ease of reference, an angle θ 140 is defined as a declination from the z-axis 106 toward the plane defined by the x-axis 102 and the y-axis 104. An angle Φ 150 is defined as an angle in the plane defined by the x-axis 102 and the y-axis with Φ starting at 0° at the x-axis 102 and increasing through Φ=90° at the y-axis 104 in a clockwise direction as viewed from the second end 112 of the first member 110 along the z-axis 106.
The graph 200 of the Φ scan shows a symmetrical co-polarization 202 radiation pattern. However, a cross-polarization 204 radiation pattern diminishes to a null 206 at an angular position of about Φ=−30°. When the radiating element 100 is used in the presence of other radiating elements, constructive and destructive interaction of radiation patterns including nulls, such as the null 206, enable an array of radiating elements 100 to be used to radiate signals in a number of different patterns that may suit a number of different applications. The configuration of the radiating elements, the phase of a signal applied to each of the radiating elements, and possibly other factors may be configured to generate different radiation patterns.
For example, four radiating elements, such as the radiating element 100, may be used to form an antenna element. The radiating elements may be arranged in a square pattern. A first member, such as the first member 110 of
In the particular embodiment illustrated in
The Φ scans 312, 314, 316, and 318 associated with each of the radiating elements 302, 304, 306, and 308 include nulls 313, 315, 317, and 319, respectively. In particular, each null is offset at an angle Φ=90° relative to the null of the adjacent radiating element 308, 302, 304, and 306. For example, the Φ scans 318 associated with the fourth radiating element 308 has a cross-polarization null 319 at about Φ=−30°; the Φ scans 312 associated with the first radiating element 302 has a cross-polarization null 313 at about Φ=+60°; the Φ scans 314 associated with the second radiating element 304 has a cross-polarization null 315 at about Φ=+150°; and the Φ scans 316 associated with the third radiating element 306 has a cross-polarization null 317 at about Φ=−120°.
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The signal may be propagated via the plurality of radiating elements, at 804. For example, the signal may be propagated in a first mode when the signal received by each of the plurality of radiating elements is in a common phase. The signal may be propagated in a second mode when the signal received by each of the plurality of radiating elements is in a shifted phase with respect to an adjacent radiating element. For example, the antenna element 500 of
The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. For example, method steps may be performed in a different order than is shown in the figures or one or more method steps may be omitted. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.
Moreover, although specific embodiments have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar results may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the description.
The Abstract of the Disclosure is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, the claimed subject matter may be directed to less than all of the features of any of the disclosed embodiments.
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