This application claims priority to Indian patent application no. 201641009006 filed on Mar. 15, 2016, the complete disclosure of which, in its entirely, is herein incorporated by reference.
Technical Field
The embodiments herein generally relate to a phased array antenna, and more particularly, to a method of transmitting circularly polarized signals while providing a down tilt by using local oscillator phase shifting technique.
Description of the Related Art
Phased array antennas operate on the principle that different phases of the signal obtained using phase shifters are fed to different radiating elements in the antenna array to steer the beam in the required direction. A phased array antenna will have in general āNā number of radiating elements. Each element will receive a signal having phase related to the direction in which transmit the beam that needs to be steered. A down tilt is necessary to the radiated beam to give proper coverage to areas close to the antenna and also not to interfere with other cell arrays. An electrical down tilt is better than a mechanical down tilt as the tilt can be easily programmed if it is electrical. If it is mechanical, then the antenna has to be manually tilted making use of motors or hinges.
Accordingly, there remains a need for a system and a method for achieving circular polarization and electrical down tilt using multiple phases of the local oscillator clock of a super heterodyne receiver.
In view of a foregoing, an embodiment herein provides a smart antenna system for generating circularly polarized and electrically down tilted phased array signals is provided. The smart antenna system includes a baseband transmitter, a first voltage controlled oscillator (VCO), a plurality of power amplifiers and a plurality of antennas. The baseband transmitter transmits a baseband signal. The first voltage controlled oscillator (VCO) generates at least one of a plurality of phase shifted local oscillator (LO) signals which modulates the baseband signal to a plurality of phase shifted intermediate frequency (IF) signals. The plurality of phase shifted intermediate frequency signals further modulated to a plurality of phase shifted radio frequency (RF) signals using a plurality of local oscillator (LO) signals generated by a second voltage controlled oscillator. The first voltage controlled oscillator (VCO) further generates a plurality of phase shifted local oscillator (LO) signals which modulate the baseband signal directly to the plurality of phase shifted radio frequency signals. The plurality of power amplifiers that amplifies the plurality of phase shifted radio frequency signals. The plurality of antennas that radiate the plurality of phase shifted radio frequency signals for generating the phased array signals. The phased array signals achieve (i) tilting of an antenna radiation plane of the plurality of radiating antennas from an initial position to a tilted position and (ii) transmitting the plurality of phase shifted radio frequency signals in a circular polarization.
In one embodiment, the circular polarization is achieved by (i) arranging a plurality of first phase array radiating elements in a horizontal plane in addition to a plurality of second phase array radiating elements in a vertical plane and (ii) feeding individual radiating elements of the plurality of first phase array radiating elements with exactly 90 degree phase shifted clocks with respect to the plurality of second phase array radiating elements.
In another embodiment, the phased array signals (i) provide proper coverage to areas close to the plurality of antennas and (ii) provide the down tilt for the antenna radiation plane to avoid interference between signals with other cell arrays.
In yet another embodiment, the first voltage controlled oscillator (VCO) generates multiple phases of the plurality of phase shifted LO signals and the second voltage controlled oscillator generates the plurality of LO signals. The multiple phases of the plurality of phase shifted LO signals from the first VCO modulate the baseband signal to generate at least one of (i) the plurality of phase shifted intermediate frequency signals and the plurality of phase shifted intermediate frequency signals further modulated to the plurality of radio frequency signals using the plurality of LO signals generated by the second VCO or (ii) the plurality of phase shifted radio frequency signals. The multiple phases further include the quadrature clocks that are generated in the first voltage controlled oscillator.
In yet another embodiment, the first voltage controlled oscillator (VCO) and the second voltage controlled oscillator are either at least one of (i) a ring oscillator voltage controlled oscillator or (ii) an inductance-capacitance (LC) voltage controlled oscillator.
In yet another embodiment, the ring oscillator voltage controlled oscillator includes a plurality of rings which are oscillating at fixed phase differences with respect to each other to generate the plurality of local oscillator (LO) signals that are phase shifted.
In yet another embodiment, the antenna radiation plane is tilted using an electrical down tilt. The electrical down tilt is a programmable tilt. The electrical down tilt is achieved by programming the phase difference between (i) the plurality of phase shifted intermediate frequency signals or (ii) the plurality of phase shifted radio frequency signals that are sent to the second phase array radiating elements.
In one aspect, a smart antenna system for generating circularly polarized and electrically down tilted phased array signals is provided. The smart antenna system includes a baseband transmitter, a first voltage controlled oscillator (VCO), a plurality of power amplifiers and a plurality of antennas. The baseband transmitter transmits a baseband signal. The first voltage controlled oscillator (VCO) generates of at least one of: (a) a plurality of first clocks or (b) a plurality of clocks. The plurality of first clocks are phase shifted which modulates the baseband signal to a plurality of phase shifted intermediate frequency signals.
The plurality of phase shifted intermediate frequency signals further modulated to a plurality of phase shifted radio frequency (RF) signals using a plurality of second clocks that is generated by a second voltage controlled oscillator. The plurality of clocks are phase shifted which modulates the baseband signal directly to the plurality of phase shifted radio frequency signals. The plurality of power amplifiers amplifies a plurality of phase shifted radio frequency signals. The plurality of antennas radiates the plurality of phase shifted radio frequency signal for generating the phased array signals. The phased array signals achieve (i) tilting of an antenna radiation plane of the plurality of antennas from an initial position to a tilted position, and (ii) transmitting the plurality of phase shifted radio frequency signals in a circular polarization. The antenna radiation plane is tilted using an electrical down tilt. The electrical down tilt is a programmable tilt. The electrical down tilt is achieved by programming the phase difference between (i) the plurality of phase shifted intermediate frequency signals or (ii) the plurality of phase shifted radio frequency signals that are sent to a plurality of second phased array radiating elements.
In one embodiment, the circular polarization is achieved by (i) arranging a plurality of first phase array radiating elements in a horizontal plane in addition to the plurality of second phase array radiating elements in a vertical plane and (ii) feeding individual radiating elements of the plurality of first phase array radiating elements with exactly 90 degree phase shifted clocks with respect to the plurality of second phase array radiating elements.
In another embodiment, the second voltage controlled oscillator includes a plurality of second clocks. The plurality of second clocks modulates the plurality of phase shifted intermediate frequency signals to the plurality of phase shifted radio frequency signals.
In another aspect, a method for generating circularly polarized and electrically down tilted phased array signals is provided. The method includes the steps of: (i) transmitting, using a baseband transmitter, a baseband signal; (ii) generating, using a first voltage control oscillator (VCO), at least one of (i) a plurality of first clocks that are phase shifted which modulates the baseband signal to a plurality of phase shifted intermediate frequency signals, wherein the plurality of phase shifted intermediate frequency signals are further modulated to a plurality of phase shifted radio frequency (RF) signals using a plurality of second clocks that is generated by a second voltage controlled oscillator or (ii) a plurality of clocks that are phase shifted which modulates the baseband signal directly to the plurality of phase shifted radio frequency signals; (iii) amplifying, using a plurality of power amplifiers, the plurality of phase shifted radio frequency signals; (iv) transmitting, using a plurality of antennas, the plurality of phase shifted radio frequency signals in a circular polarization; and (vii) tilting, using an electrical tilt down, an antenna radiation plane of the plurality of antennas using the phased array signals. The phased array signals (i) provide proper coverage to areas close to the plurality of antennas and (ii) provide the down tilt for the antenna radiation plane to avoid interference between signals with other cell arrays.
In one embodiment, the method further includes the steps of: (i) arranging a plurality of first phase array radiating elements in a horizontal plane in addition to a plurality of second phase array radiating elements in a vertical plane; and (ii) feeding individual radiating elements of the plurality of first phase array radiating elements with exactly 90 degree phase shifted clocks with respect to the plurality of second phase array radiating elements to achieve the circular polarization.
In another embodiment, the first voltage controlled oscillator and the second voltage controlled oscillator are either at least one of (i) a ring oscillator voltage controlled oscillator or (ii) an inductance-capacitance (LC) voltage controlled oscillator.
In yet another embodiment, the ring oscillator voltage controlled oscillator includes a plurality of rings that oscillate at fixed phase differences with respect to each other to generate multiple phases of a plurality of phase shifted local oscillator (LO) signals.
These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which:
The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein. Referring now to the drawings and more particularly to
The circular polarization is achieved by (i) arranging the plurality of first phase array radiating elements 202A-N in the horizontal plane in addition to the plurality of second phase array radiating elements 204A-N in the vertical plane, (ii) feeding the individual radiating elements of the plurality of first phase array radiating elements 202A-N with exactly 90 degree phase shifted clocks with respect to the plurality of second phase array radiating elements 204A-N.
In one embodiment, the ring oscillator voltage controlled oscillator includes a plurality of rings that oscillate at fixed phase differences with respect to each other to generate multiple phases of a plurality of phase shifted local oscillator signals as required. The plurality of antennas 102A-N radiates the plurality of phase shifted radio frequency signals in the circular polarization. The antenna radiation plane of the plurality of antennas 102A-N is tilted from the initial position 104 to the tilted position 106 using a programmable electrical down tilt. In one embodiment, the down tilt is an electrical down tilt. The electrical down tilt is achieved by programming the phase difference between (i) the plurality of phase shifted intermediate frequency signals or (ii) the plurality of phase shifted radio frequency signals that are sent to the plurality of second phase array radiating elements 204A-N.
The Programmable Electrical down tilt may be achieved by choosing one or more phases among the many phases of the ring oscillator VCO. In yet another embodiment, based on the chosen phases, their quadrature clocks should be fed to the plurality of first phase array radiating elements 202A-N to achieve perfect circular polarization with respect to the plurality of second phase array radiating elements 204A-N.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein may be practiced with modification within the spirit and scope of the appended claims
Number | Date | Country | Kind |
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201641009006 | Mar 2016 | IN | national |