CN106935982B

CN106935982B - Planar array antenna

Info

Publication number: CN106935982B
Application number: CN201511030537.3A
Authority: CN
Inventors: 邓海; 金永斗; 刘洋
Original assignee: Aisino Corp
Current assignee: Aisino Corp
Priority date: 2015-12-31
Filing date: 2015-12-31
Publication date: 2020-09-25
Anticipated expiration: 2035-12-31
Also published as: CN106935982A

Abstract

The invention relates to the field of communication, and discloses a planar array antenna which comprises a substrate, a plurality of radiating devices attached to a first surface of the substrate, and a power divider connected with the radiating devices through microstrips, wherein each radiating device comprises 4 rectangular patch antennas connected through microstrips, and the 4 rectangular patch antennas are arranged to have phase differences of 0 degrees, 45 degrees, 90 degrees and 135 degrees respectively. Through the technical scheme, the individual radiators of the array antenna are sequentially rotated to artificially add the phase differences of 0 degrees, 45 degrees, 90 degrees and 135 degrees, and the individual radiators are rotated by 45 degrees in the direction of the right-hand circularly polarized wave, so that the circularly polarized wave can be realized according to the superposition of the polarized waves even if the central frequency is deviated.

Description

Planar array antenna

Technical Field

The present invention relates to the field of communications, and in particular, to a planar array antenna.

Background

An intelligent traffic information system (ITS) is a system technology related to a traffic system and a sophisticated technology that is inserted into electric appliances, electronics, control, information, communication, computers, automobiles, etc., and is also a new traffic system that is generated in order to effectively cope with increasingly deeper traffic problems and effectively improve a traffic environment of traffic mobility, safety, and efficiency along with the progress of industrial development and urbanization.

The ITS improves the utilization efficiency of traffic facilities, relieves traffic difficulties, ensures the smoothness of roads and complete vehicles, reduces traffic accidents, realizes the informatization of mass traffic and the automation and informatization of a logistics system, provides various traffic information collection and filtration services, and can provide convenience and traffic safety for users and managers.

Dedicated Short Range Communication (DSRC) is a new short range communication means for realizing ITS, and is considered to be the best communication technology for realizing ITS at present. DSRC is a communication system that realizes wireless digital communication between a Road Side Unit (RSU) installed on a roadside and an end-point unit (OBU) on a vehicle, and is a communication method suitable for performing various services such as information collection and transmission of traffic signals with an Electronic Toll Collection (ETC) system of a vehicle-passing unmanned toll collection system.

The use frequency band of the dedicated short-range communication (DSRC) is 5.8GHz, the communication distance between the Road Side Unit (RSU) and the vehicle is several meters to several hundred meters, and the data transmission speed can reach the wireless communication speed of more than two-way 1 Mbps. A dedicated short-range communication (DSRC) system forming the ITS system is designed into a two-way communication mode, and factors such as vehicle speed on a lane, the number of lanes, the width of the lane and the like are considered in the design, so that the system can guarantee the smoothness of communication in different traffic environments.

Because of this, the antenna of the roadside unit (RSU) must limit the beam width and the side lobe size within its horizontal range in order to prevent interference with communications on other vehicles on the surrounding lanes; also, for long-distance communication characteristics, a structural design having high gain and a circular polarization (RHCP) characteristic capable of receiving signals reflected multiple times is required.

In order to accommodate the smooth wireless communication using a Dedicated Short Range Communication (DSRC) system in the 5.8GHz band, an antenna (OBU) of a vehicle communication device mounted on a vehicle is required to be designed as a wide 3dB beam antenna that can communicate smoothly with a roadside base station regardless of the mounting position and location, but the antenna design of a roadside unit of the DSRC is limited by a radiation beam that can communicate with the OBU mounted on the vehicle only within a specific range. The antenna for the roadside unit is required to have a vertical 3dB beam width suitable for a road width of 3-4 m, a horizontal 3dB beam width capable of communicating within a maximum of 10-15 m in a road traveling direction, and a right-hand circular polarization (RHCP) characteristic in order to minimize the influence of multiple reflections reflected by other reflectors. In order to realize such an antenna having high gain characteristics and circular polarization characteristics in a planar form, a microstrip array antenna having a single feed structure is designed. The circularly polarized array antenna with the single feed structure realizes multiple matching lines by offsetting unnecessary radiation of the feed line, and maintains the proposed axial ratio characteristic and the proper 3dB beam width and side lobe size. Generally, a relatively simple method of implementing a circularly polarized wave on a quadrangular microstrip of an array in order to obtain a high gain is exemplified by a method of feeding a power distribution device having a phase difference of 90 ° or a Hybrid (Hybrid) device.

By feeding on radiating microstrip edges, inducing TM^x ₀₁₀Mode waves, in turn TM induced by feeding on the other side of the radiating microstrip^x ₀₀₁The wave is circularly polarized. However, when the above feeding method is adopted, it is very difficult to obtain a corresponding feeding distance in the circularly polarized wave generated in the high-order mode, and the complicated feeding line not only generates unnecessary radiation to reduce the radiation efficiency of the antenna, but also increases the physical volume of the array antenna. Therefore, the array antenna is preferably fed in a single feeding manner. A specific implementation method for realizing circular polarization by single feed is a method of generating the same magnitude (intensity) in any frequency and feeding at 2 orthogonal mode positions. That is, the radiation microstrip is physically deformed so that 2 principal modes generated in a certain center frequency are perpendicular to each other and have the same size, and when a phase difference of 90 ° exists, circular polarization is generated. The electric fields radiated by the modes are perpendicular to each other and produce circular polarization in the broadside direction.

The principle of generating circular polarization of a single feed angle truncated (Corner truncated) radiating element that is physically deformed on the radiating element is as follows: the current in the feeder direction of a single feed exciting (excitation) onto the radiating patch is split into two orthogonal modes, the magnitude (amplitude) and phase of which are at the central frequency f_oCentered at a resonant frequency f with a phase difference of 90 DEG between both sides_aAnd f_bOrthogonal mode of (2). Such a circular polarized wave antenna of a single feed structure is a form which is very useful when a power divider using dual vertical feeds without a space or an array radiating device is added for obtaining a high gain. However, compared with the method of generating circularly polarized waves by using the dual feeding method, the single feeding method also has the following disadvantages: the axial ratio bandwidth is narrow, and the resonance frequency bandwidth and the axial ratio bandwidth of the antenna are relatively sensitive to the physical deformation of the patch. Furthermore, the feed network of the antennas arrayed to obtain the high radiation gain required by the system is placed in a narrow space, which may generate radiationMutual coupling between the emitter devices and leakage of the feed lines themselves, which can add extra sidelobe levels and non-paradoxical effects on the beam shape.

The low side lobe requirement characteristic of an array antenna for a Road Side Unit (RSU) is achieved by a weight value method of controlling a feed current of an individual radiating device. The array antenna is structured to increase the number of radiators to increase the gain of the antenna and obtain the narrow beam width required by the system, but also causes numerous side lobes to be generated.

In view of the above problems, no good solution exists in the prior art.

Disclosure of Invention

An object of the present invention is to provide a planar array antenna having high gain and low sidelobe characteristics.

In order to achieve the above object, the present invention provides a planar array antenna including a substrate and a plurality of radiation devices attached to a first surface of the substrate and a power divider connecting the plurality of radiation devices by a microstrip, wherein each of the radiation devices includes 4 rectangular patch antennas connected by a microstrip, the 4 rectangular patch antennas being disposed to have phase differences of 0 °, 45 °, 90 ° and 135 °, respectively.

Furthermore, each of the 4 rectangular patch antennas is cut in a diagonal direction at the upper right corner and the lower left corner with reference to the microstrip input end.

Further, the distance between two adjacent 4 rectangular patch antennas is greater than lambdag/2 and smaller than lambdag, wherein lambdag is the wavelength in the medium.

Further, the range of the spacing between two adjacent 4 rectangular patch antennas is greater than 0.8 λ g and less than λ g.

Further, the distance between two adjacent 4 rectangular patch antennas is 0.72 λ g.

Further, the material of the substrate is F4B.

Further, the dielectric constant of the substrate is 2.2.

Further, the number of the plurality of radiating devices is 4, and the 4 radiating devices are attached to the first surface of the substrate so that the rectangular patch antenna is in a 2 × 8 array.

Further, the 2x8 array is a first stage in

rows

1 and 2, a second stage in row 3, and a third stage in row 4 from the centerline to both sides, wherein the first, second, and third stages conform to a three-stage taylor distribution.

Further, the electric power distribution of the power divider located between the first phase and the second phase is 1: 4; and the electric power distribution of the power divider located between the second phase and the third phase is 1: 4.

through the technical scheme, the individual radiators of the array antenna are sequentially rotated to artificially add the phase differences of 0 degrees, 45 degrees, 90 degrees and 135 degrees, and the individual radiators are rotated by 45 degrees in the direction of the right-hand circularly polarized wave, so that the circularly polarized wave can be realized according to the superposition of the polarized waves even if the central frequency is deviated.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

fig. 1(a) and fig. 1(b) are schematic structural diagrams of a planar array antenna according to an embodiment of the present invention;

fig. 2 is a detailed front view of an array antenna using a sequential rotation manner in an embodiment of the present invention;

FIG. 3 is a schematic diagram of a power divider for implementing multi-port current division according to an embodiment of the present invention;

FIGS. 4(a) and 4(b) are schematic diagrams of Taylor distributed current distribution networks for sequentially rotating array antennas;

fig. 5 is a reflection loss diagram of a 2 × 8 array antenna of the sequential rotation scheme with low sidelobe characteristic;

fig. 6 is an axial ratio characteristic diagram of a 2 × 8 array antenna in a sequential rotation manner;

fig. 7(a) shows a cross polarization discrimination (XPD) characteristic phi of a 2 × 8 array antenna of the sequential rotation system of 0 °;

fig. 7(b) shows a cross polarization discrimination (XPD) characteristic phi of a 2 × 8 array antenna of the sequential rotation system of 90 °;

FIG. 8(a) is a 5790MHz vertical plane pattern;

FIG. 8(b) is a 5800MHz vertical plane pattern;

FIG. 8(c) is a 5830MHz vertical plane pattern;

FIG. 8(d) is a 5840MHz vertical plane pattern;

FIG. 9(a) is a 5790MHz horizontal plane pattern;

FIG. 9(b) is a 5800MHz horizontal plane pattern;

FIG. 9(c) is a 5830MHz horizontal plane pattern;

FIG. 9(d) is a 5840MHz horizontal plane pattern; and

fig. 10 is a graph showing the actual test results of the read range in combination with the response sensitivity of a conventional OBU.

Description of the reference numerals

100: a substrate;

101: a connection hole connecting an external structure (antenna housing) and a metal support;

200: an RF radiating device having right-hand circularly polarized (RHCP) radiation characteristics;

210: a single feed network feeding the radiators;

220: a feed network for realizing electric distribution in different stages;

300: a ground plane commonly grounded to the antenna;

400: an RF port wired to an external signal source.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

Hereinafter, the constituent features and effects of the present invention will be described in detail with reference to the accompanying drawing.

Fig. 1(a) and fig. 1(b) are schematic structural diagrams of a planar array antenna according to an embodiment of the present invention. The planar array antenna structure can be mounted at an arbitrary angle by fixing an external structure (housing) and a metal holder through an even number of mounting holes 101 provided around the substrate 100. The integrated Road Side Unit (RSU) microstrip array antenna can adjust the installation angle of the array antenna at any angle inside the structure for specifying the radiation directivity in a specific direction, and the radiation directivity can be maintained according to the installation angle of the structure itself for the array antenna having the same installation angle with the structure (housing). The planar array antenna structure provided by the embodiment of the invention is an antenna for a Road Side Unit (RSU) based on dedicated short-range communication (DSRC), and the planar array antenna structure comprises the following specific components: a radiation device 200 mounted on a substrate 100 of a limited area for reliably transmitting/receiving an array antenna for communication of a 5.8GHz band; a feeder line (or microstrip) 210 for exciting a signal to the radiation device in a single feeding manner; electric

power distribution networks

210 and 220 of different stage taylor distributions are implemented in the return path of the feed distributor for proper beam width and low side lobe characteristics; a ground portion 300 on the back surface of the substrate 100, which shares the same ground with the array antenna; a port 400 for connection to an RF connector of an external signal source. The

distribution networks

210 and 220 providing signals to the radiating device 200 utilize the basic λ g/4 impedance transformation principle, where λ g is the wavelength in the medium (e.g., F4B), in order to improve the matching characteristics between the distribution networks, the form is changed into a cut form, and a design is adopted that is close to the radiating element 200 to minimize the interference and coupling effects between the distribution network 210 and the radiating element 200.

The principle of circular polarization generation of the radiating device 200 is to use two orthogonal modes into which a current excited into the feeder direction of a single feed on the radiating element is split. The RF substrate 100 used in the embodiment of the present invention may be an F4B plate material having a thickness of 1.6mm and a dielectric constant (r) of 2.2.

Fig. 2 is a detailed front view of an array antenna using a sequential rotation manner in an embodiment of the present invention. In order to generate right-hand circular polarization (RHCP) of a single-feed microstrip array antenna, the input port of a microstrip is used as a reference, the upper right corner and the lower left corner of a common 4-corner patch (rectangular patch) antenna are cut at a diagonal angle, each radiating device 200 includes 4 rectangular patch antennas (for example, square patch antennas) connected through the microstrip, and the two connected rectangular patch antennas are connected by using a λ g/4 impedance converter, so that impedance matching between a multi-feed line and the radiating device of a single antenna is realized. Generally, the axial ratio bandwidth of a single array antenna is sharply reduced as the distance from the center frequency is increased, and the gain is lower than the standard of a Road Side Unit (RSU) antenna of the DSRC.

The basic principle of the sequentially rotating array antenna is to adjust the distance from a reference feed point to each rectangular patch antenna so as to cancel the reflected voltage at the feed point. In order to compensate for the phase delay in the sequence of the rectangular patch antennas caused by the difference in the feeder lines, the rectangular patch antennas should be physically rotated in sequence so that the electric fields radiated from the rectangular patch antennas are in the same direction at the same time. In the embodiment of the present invention, the rectangular patch antennas are artificially given phase differences of 0 °, 45 °, 90 °, and 135 °, and are sequentially rotated by 45 ° in a right-hand circular polarization (RHCP) direction. Thus, the circularly polarized wave can be realized by means of superposition of the polarized waves although the frequency is deviated from the resonance center frequency. Those skilled in the art know that when designing array antennas on the same plane, it is very important that a factor to be considered in the design is a distance between the center of the radiating device and the center thereof, i.e., a pitch between the radiating devices. This becomes an important factor for determining the direction and gain of the main lobe, and when the wavelength is larger than the wavelength (λ g), a Grating lobe (Grating lobe) having the same size as the main lobe is generated in the detection range of the array antenna. Conversely, if the radiator element pitch is too small, grating lobes are not produced, but the mutual coupling between the radiator elements is responsible for distortion of the far-field radiation lobe, thereby increasing the side lobe level and also producing a null radiation lobe (Pattern null).

Therefore, the distance between two 4 rectangular patch antennas is selected in the range of lambdag/2 < d < lambdag, and the grating lobe minimization in the specified main 4 corners is realized. In general, the radiation gain is increased as the pitch of the rectangular patch antenna is increased, but the gain may be decreased when the pitch is larger than 0.7 λ g. In addition, the axial ratio variation following the pitch of the rectangular patch antenna is such that the axial characteristics are relatively good when the pitch is maintained at 0.8 λ g or more. This is because the larger the rectangular patch antenna pitch, the smaller the mutual coupling effect therebetween. In order to satisfy the operating characteristics of the circular polarized wave antenna, a range of 0.8 λ g < d <1.0 λ g, which is excellent in axial ratio characteristics, may be selected, and d, which is the optimum gain characteristic, may be selected to be 0.72 λ g.

In order to meet the characteristic requirement of low side lobe of a Road Side Unit (RSU) array antenna, the low side lobe is realized by controlling current weighted value on a rectangular patch antenna. In the array antenna structure, the radiation gain of the antenna is increased by increasing the number of rectangular patch antennas, and the narrow-band beam width required by the system is obtained, but a plurality of side lobes are generated at the same time. Therefore, in order to obtain a proper beam width and low sidelobe characteristic, it is necessary to select an optimal array pitch and adopt a taylor distribution method to achieve compactness and better performance of the entire antenna structure.

Fig. 3 is a schematic diagram of a power divider for implementing multi-port current division according to an embodiment of the present invention. As shown in fig. 3, in order to provide a predetermined feeding current to the individual rectangular patch antenna, the width of the power divider is designed to be asymmetric to the left and right, so as to embody different impedance designs, and finally, the impedance matching of the array feeding loop is realized. With a Taylor distribution, where the side lobe is predetermined to a design value of-25 dB, the array device is designed to have an electrical power distribution of 1: 4 (0.25: 1). The predetermined design value of the side lobe size required by the system is-25 dB, and when the distribution of the array device is expanded to 3-stage distribution, the feed current on the radiation device of the array can be controlled to be 1: 0.25: 0.0625. in the current distribution method for controlling different stages according to the taylor distribution, impedance matching of 50 Ω is adopted for 3 ports of a basic power divider of an array antenna, and in order to realize 1: 4 (0.25: 1), and a 56 Ω and 112 Ω λ g/4 impedance transformation loop can be connected to the port 2 and the port 3, respectively, by using the λ g/4 impedance transformation principle.

Fig. 4(a) and 4(b) are schematic diagrams of taylor distribution current distribution networks of a sequentially rotating array antenna, and fig. 4 shows an array antenna using a power distribution circuit network according to taylor distribution in order to improve the sidelobe level of a 2x8 antenna. The planar array antenna shown in fig. 4 constitutes a 2 × 8 rectangular patch antenna array for 4 radiating devices arranged, the 2 × 8 array being a 1 st stage, a 2 nd stage in a 3 rd row, and a 3 rd stage in a 4 th row from the center line to both sides, wherein the 1 st stage, the 2 nd stage, and the 3 rd stage conform to a three-stage taylor distribution. The electric power distribution of the power divider located between the 1 st and 2 nd phases is 1: 4; and the electric power distribution of the power divider located between the 2 nd and 3 rd phases is 1: 4. a power distribution circuit network is arranged for controlling the weight value of the current between the stage 1 and the adjacent stage 2 of the arrangement center, and the power distribution circuit network is also formed between the stage 2 and the stage 3 based on the unit sequential rotation mode. The rectangular patch antenna arranged in the vertical plane forms 2 radiating oscillators according to a unit sequential rotation mode, and because the arrangement structure cannot effectively control the current weight value, a distribution circuit network is not formed in the vertical plane. The unit array of the sequentially rotated array antenna in the present invention may be an array expansion composition of various geometries in the horizontal plane.

Fig. 5 is a reflection loss diagram of a 2 × 8 array antenna of the sequential rotation system with low sidelobe characteristic. As shown in fig. 5, the reflection loss bandwidth of the 10dB reference is from 5.6GHz to 5.92GHz, i.e., has a bandwidth of 320MHz, which is about 5.5% of the bandwidth, calculated at a center frequency of 5.8 GHz. This covers the range of 5.79GHz-5.80GHz up-link frequency and 5.83GHz-5.84GHz down-link frequency required by standard systems, with a minimum reflection loss value of 5.8GHz, which is about-33 dB.

Fig. 6 is an axial ratio characteristic diagram of a 2 × 8 array antenna of the sequential rotation system. As shown in fig. 6, in the range of angle Θ (theta) of 5.82GHz at the center frequency from-90 ° - +90 °, the horizontal in-plane axial ratio when Φ is 0 ° and the vertical in-plane axial ratio when Φ is 90 °. In the reference range of 3dB, the axial ratio characteristic is such that Φ at an angle θ of 0 ° (the direction in which the radiation gain is maximum) becomes 0.4dB in the direction of 0 °, and Φ becomes 0.5dB in the direction of 90 °. In the implementation mode of the invention, the upper right corner and the lower left corner of a common 4-corner patch antenna are cut off in the diagonal direction, and in order to embody the unit sequence rotation array antenna, a mode of artificially applying phase differences of 0 degree, 45 degrees, 90 degrees and 135 degrees on each patch is adopted, so that the satisfactory axial ratio characteristic in the whole bandwidth required by the system is realized.

Fig. 7(a) and 7(b) show Cross-polarization discrimination (XPD) characteristics of a 2 × 8 array antenna in a sequential rotation manner, in which Φ is 0 ° and Φ is 90 ° directions at a center frequency of 5.82GHz, according to an embodiment of the present invention. As shown in fig. 7(a), the right-hand circular polarization (RHCP) radiation gain at the maximum radiation gain is 17.1dB, the LHCP radiation gain is-13.7 dB, and the drop (size difference) of the cross polarization (XPD) is 31.2dB in the direction of Φ equal to 0 °. In the radiation angle of 3dB of maximum radiation gain phase difference, the difference of cross polarization (XPD) is 16.6dB, and the requirements of the cross polarization (XPD) difference of more than 15dB and the cross polarization discrimination (XPD) difference of more than 10dB in the radiation angle required by the system standard are met.

Fig. 7(b) shows that the right-hand circular polarization (RHCP) radiation gain at the maximum radiation gain is 17.2dB, the LHCP radiation gain is-14.0 dB, and the difference in cross polarization discrimination (XPD) is 31.2dB in the direction of Φ ═ 90 °. Moreover, the difference in cross polarization discrimination (XPD) is 10.2dB in the direction where the gain ratio is less than the maximum gain by 3 dB. Therefore, the circular polarization characteristic of the sequential rotation array technique of the present invention has excellent performance as shown by the axial ratio characteristic and cross polarization (XPD) result in the full frequency band.

Fig. 8(a) - (d) and fig. 9(a) - (d) show the far field radiation patterns at the azimuth angle and elevation angle of the center frequency, fig. 8(a) - (d) refer to the radiation patterns in the vertical plane, and fig. 9(a) - (d) are the radiation patterns in the horizontal plane. As shown in fig. 8(a) - (d), the radiation angle that produces the strongest radiation is in the vertical plane perpendicular to the plane of the array antenna, with a maximum radiation gain of 17dBi, a main lobe Half power width (3 dB) in the vertical plane of 38 °, and a front-to-back ratio of 23 dB. As shown in fig. 9(a) - (d), the maximum radiation gain in the horizontal plane is 17dBi, the main lobe half-power width in the vertical plane is 9 °, and the front-to-back ratio is 23 dB.

As shown in the far-field radiation diagram, the half-power width of the main lobe in the vertical plane is about 38 °, which can effectively distribute the radiation directivity of the antenna in the traveling direction of the vehicle, and the half-power width of the main lobe in the horizontal plane is about 9 °, which is relatively narrow, so that the mutual interference of adjacent lanes can be avoided.

Fig. 10 is a graph showing the actual test results of the read range in combination with the response sensitivity of a conventional OBU. As shown in fig. 10, a Road Side Unit (RSU) antenna according to the sequential rotation technique provided by the embodiment of the present invention was tested in an actual use environment, and the relative induction strength of the OBU is illustrated on the ground surface. The ground surface on the side of the driving road in the vehicle entering direction is 5 m high, and the RSU array antenna is installed at an inclination angle of 45 degrees. The test results showed that the maximum recognition distance in the traveling direction of the vehicle at this time was 20 meters, and the maximum recognition distance in the road width direction was 3.4 m.

The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. A planar array antenna comprising a substrate and a plurality of radiating elements attached to a first surface of the substrate and a power divider connecting the plurality of radiating elements by a microstrip, wherein

Each of the radiating devices includes 4 rectangular patch antennas connected by a microstrip, the 4 rectangular patch antennas being disposed to have phase differences of 0 °, 45 °, 90 °, and 135 °, respectively;

the rectangular patch antennas are sequentially rotated by 45 ° in the right-hand circular polarization direction.

2. The planar antenna of claim 1, wherein each of the 4 rectangular patch antennas is diagonally chamfered at an upper right corner and a lower left corner with respect to the microstrip input terminal.

3. The planar antenna of claim 1, wherein a spacing between two adjacent 4 of the rectangular patch antennas ranges from greater than λ g/2 to less than λ g, where λ g is a medium wavelength.

4. The planar array antenna of claim 3, wherein a distance between two adjacent 4 rectangular patch antennas is in a range of greater than 0.8 λ g and less than λ g.

5. The planar antenna of claim 3, wherein a spacing between two adjacent 4 of the rectangular patch antennas is 0.72 λ g.

6. The planar antenna of claim 1, wherein the substrate is F4B.

7. The planar antenna of claim 6, wherein the substrate has a dielectric constant of 2.2.

8. The planar antenna of claim 1, wherein the plurality of radiating elements is 4 in number, the 4 radiating elements being attached to the first surface of the substrate such that the rectangular patch antenna is in a 2x8 array.

9. The planar antenna of claim 8, wherein the 2x8 array is flanked on rows 1 and 2 by a first phase, row 3 by a second phase, and row 4 by a third phase from a center line, wherein the first phase, the second phase, and the third phase conform to a three-phase taylor distribution.

10. The planar antenna of claim 9, wherein a power divider located between the first stage and the second stage has an electrical power division of 1: 4; and

the electric power distribution of the power divider located between the second stage and the third stage is 1: 4.