Patent Application
20180159246
The present invention relates generally to multiple-input multiple-output (MIMO) antenna arrays, and more particularly, to a modular and configurable MIMO antenna array architecture.
Advanced radar systems in use today use a multiple-input multiple-output (MIMO) concept that employs multiple antennas at the transmitter to transmit independent (orthogonal) waveforms and multiple antennas at the receiver to receive the radar echoes. In a “collocated” MIMO radar configuration, the antennas in both the transmitter and the receiver are spaced sufficiently close so that each antenna views the same aspect of an object such that a point target is assumed. In the MIMO receiver, a matched filter bank is used to extract the orthogonal waveform components. When the orthogonal signals are transmitted from different antennas, the echoes of each signal carry independent information about detected objects and the different propagation paths. Phase differences caused by different transmitting antennas along with phase differences caused by different receiving antennas mathematically form a virtual antenna array that provides for a larger virtual aperture using fewer antenna elements. Conceptually, the virtual array is created by an interleaving between each of the transmitter Tx and receiver Rx antenna elements such that the elements in the virtual array represent Tx-Rx pairs for each of the transmitter Tx and receiver Rx antennas in the MIMO array. For collocated MIMO antennas, a transmit array having NTx transmitter antennas and a receive array having NRx receiver antennas produces a virtual array having NTxNRx virtual receiver elements. In other words, the orthogonal waveforms are be extracted by the matched filters at the receiver such that there are a total of NTxNRx extracted signals in the virtual array.
As understood by those skilled in the art, the interleaving between the transmitter Tx and receiver Rx antenna elements in uniformly spaced linear arrays requires a non-half-wavelength interelement spacing between either the transmit or receive array elements in order to maintain a uniform virtual array. For example, as illustrated by the known MIMO array 10 configuration in
Traditionally, MIMO antenna arrays as shown in
According to an embodiment of the invention, there is provided a multiple input multiple output (MIMO) antenna for a radar system, the antenna for at least one first module having a plurality of antenna elements forming a linear array, wherein the plurality of antenna elements in the linear array are uniformly separated by a first distance; and for at least one second module having a plurality of antenna elements forming a planar array, wherein the plurality of antenna elements in the planar array are uniformly separated by a second distance; and wherein the at least one first module and the at least one second module are selectively configured to function as transmitter modules or receiver modules, and wherein an interleaving between the plurality of antenna elements in the linear array of the at least one first module with the plurality of antenna elements in the planar array of the at least one second module produces a uniform virtual antenna array.
According to another embodiment of the invention, there is provided a multiple input multiple output (MIMO) antenna for a radar system, the antenna for a modular antenna array assembly having a plurality of antenna boards, each of the plurality of antenna boards having an array portion and a circuit portion; and wherein the array portion of at least one of the plurality of antenna boards includes a first plurality of antenna elements forming a linear array, and wherein the array portion of at least another one of the plurality of antenna boards includes a second plurality of antenna elements forming a planar array; and wherein the circuit portion of each of the plurality of antenna boards includes one or more electronic devices configured to control the array portions of the plurality of antenna boards to function as a transmitter antenna array or as a receiver antenna array, and wherein the modular antenna array assembly has at least one of the plurality of antenna boards configured as a transmitter antenna array and at least one of the plurality of antenna boards configured as a receiver antenna array.
According to another embodiment of the invention, there is provided a multiple input multiple output (MIMO) antenna for a radar system, the antenna for a modular antenna array assembly having one or more linear antenna array boards each having a plurality of antenna elements forming a uniform linear array, and one or more planar antenna array boards each having a plurality of antenna elements forming a uniform planar array, wherein each of the one or more linear antenna array boards and each of the one or more planar antenna array boards includes circuitry configured to operate the linear arrays of the one or more linear antenna array boards and the planar arrays of the one or more planar antenna array boards as either transmitter arrays or receiver arrays; wherein the modular antenna array assembly has an equal number of linear antenna array boards and planar antenna array boards, and when the circuitry of the one or more linear antenna array boards operates as one of a transmitter array or a receiver array, then the circuitry of the one or more planar antenna array boards operates as the other.
One or more embodiments of the invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and wherein:
The system and method described below are directed to a modular and configurable MIMO antenna array architecture. In one embodiment, the modular array includes a plurality of antenna modules, each having a plurality of antenna elements arranged to form either a linear or a planar array. Each antenna module further includes transmitter or receiver circuitry such that the linear and planar arrays on each board can be configured to operate as either a transmitter array or a receiver array. The interelement spacing between the antenna elements in both the linear and planar arrays are chosen such that the MIMO antenna array formed by a select combination of the linear and planar arrays form a uniformly spaced virtual array.
The array portion 24 of each antenna module 22 includes a plurality of antenna elements 30 arranged to form either a linear array 32 or a planar array 34. As such, each of the antenna modules 22 in antenna array 20 is configured as either a linear array module 22a or a planar array module 22b. As understood by those skilled in the art, the shape of the antenna element 30 influences the antenna response. Consistent with automotive applications, the antenna elements in the illustrated embodiment are narrow in the horizontal axis and long in the vertical axis, which generates a narrow radiation angle in the vertical axis and a wide angle in the horizontal axis. However, the shape of the antenna elements in the illustrated embodiment is merely exemplary and non-limiting. One of ordinary skill in the art appreciates that the array configuration disclosed herein for each of the antenna modules 22 may be applicable to any suitably shaped antenna element.
The antenna elements 30 in the linear array modules 22a are separated by a distance dLA, which in one embodiment is uniform and equal to 0.5λ, to maintain a uniform and unambiguous beam pattern in the azimuth domain. Referring to planar array module 22b, the planar array 34 has a plurality of columns and rows having a total of MPA×NPA antenna elements 30, where MPA is the number of antenna elements in each column and NPA is the number of antenna elements in each row. In one embodiment, the adjacent antennas elements 30 in any given row or column of planar array 30 are equidistant with interelement spacing dPA. In an antenna array having at least one linear array module 22a and at least one planar array module 22b, the interelement spacing dPA is proportional to the aperture of the linear array 32 in order to maintain uniform spacing in the virtual array. In one embodiment, the interelement spacing dPA=dLANLA, where dLA is the distance between the antenna elements 30 in the linear array modules 22a and NLA is the number of antenna elements 30 in the linear array module 22a. While the spacing dPA between phase centers of the antennas elements 30 in the planar array 34 is the same in the horizontal and vertical axes, due to the geometry of the antenna elements, the physical appearance of the spacing between the antenna elements 30 in the horizontal and vertical axes appears different. In other words, the physical distance between the antenna elements 30 in each row along the horizontal axis appears wider relative to the physical spacing between the antenna elements 30 in each column along the vertical axis.
The circuit portion 26 of each of the antenna modules 22 includes one or more electronic devices 36 associated with the plurality of antenna elements 30. The electronic devices 36 may include without limitation, components and/or devices that comprise transmitter and receiver circuitry such as, for example, power dividers, amplifiers, converters, filters, etc. as known in the art. In the embodiment shown in
In the exemplary embodiment shown in
Moreover, in general, the linear array modules 22a function together and the planar array modules 22b function together such that all of the linear array modules 22a in an antenna array 20 are configured to operate in the same transmitter or receiver manner (i.e., as one of either a transmitter or receiver array), and all of the planar array modules 22b in the antenna array 20 are configured to operate in the same transmitter or receiver manner. In other words, the linear arrays 32 for a particular array all function as either receiver arrays or transmitter arrays, but not both in a given antenna array 20. The same applies for the planar arrays 34 in that all function as receiver arrays or transmitter arrays, but not both. In addition, the linear arrays 32 and the planar arrays 34 have distinct and opposite functionality in that if the linear arrays 32 are configured to operate as receiver arrays, then the planar arrays 34 are configured to operate as transmitter arrays, and vice versa. For example, in one particular implementation, if the linear array modules 22a shown in
The linear array modules 22a and the planar array modules 22b, both as individual modules relative to one another, and as a combined modular antenna array 20 as shown in
As understood by those skilled in the art, to form a virtual array having uniform spacing, the interelement spacing between like elements 30 in adjacent modules (i.e., between adjacent linear array modules 22a and between adjacent planar array modules 22b) must also be spaced according to the convention set forth above. More specifically, to maintain a uniform virtual array, the spacing between antennas elements 30 in the rows and columns between adjacent planar array modules 22b must also be equidistant and equal to the interelement spacing dPA as shown in
As shown in
It is to be understood that the foregoing is a description of one or more embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.
As used in this specification and claims, the terms “e.g.,” “for example,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.
