CN103682612A - Rectangular slotted dual-frequency microstrip antenna with swastika-shaped arm closed-loop coupling regulation for Beidou system - Google Patents

Abstract

The invention relates to a rectangular slotted dual-frequency microstrip antenna with a swastika arm closed-loop coupling control for a Beidou system, and relates to a dual-frequency microstrip antenna. There is a dielectric substrate, and a rectangular patch is arranged on the upper surface of the dielectric substrate. There are rectangular grooves symmetrically opened at the midpoints of the four sides of the rectangular patch. The center of the wide side of each groove is vertically connected to the coupling arm, which extends to the outer edge of the rectangle and then bends counterclockwise. folded to form a "swastika" arm loading, and the loading end forms a capacitive coupling closed loop with the outer edge of the rectangular antenna; the "swastika" arm is composed of two rectangular straight arms with similar dimensions, and the included angle is 90°; the length of the upper and lower rectangular slots The length of each rectangular straight arm of the connected folding arm is 0.1 mm longer than the length of the left and right rectangular slots and the length of each rectangular straight arm of the folding arm; a grounding plate is provided on the lower surface of the dielectric substrate. It has novel structure, flexible control, low return loss, high gain, meets circular polarization, and has little interference with receiving and transmitting signal channels.

Description

Rectangular Slotted Dual-band Microstrip Antenna with Swastika Arm Closed-loop Coupling Control for Beidou System

technical field

The invention relates to a dual-frequency microstrip antenna, in particular to a rectangular-slotted dual-frequency microstrip antenna with a swastika arm closed-loop coupling control for the Beidou satellite navigation and positioning system.

Background technique

Satellite navigation system is an important space infrastructure. With the continuous innovation of navigation technology, satellite navigation system is widely used in surveying and mapping, telecommunications, water conservancy, fishery, transportation, forest fire prevention, disaster relief and public security, etc. area, which has both political and military significance. As the largest developing country in the world, my country has developed the fourth largest global satellite navigation system, the Beidou satellite navigation and positioning system, after the US GPS, Russia's GLONASS and Europe's Galileo.

The Beidou satellite navigation and positioning system (BeiDou) is a regional active three-dimensional satellite positioning and communication system independently developed by China. So far, China has successfully launched 4 Beidou-1 navigation and positioning satellites and 16 Beidou-2 navigation and positioning satellites, has completed the Beidou-1 navigation test system, and is building the Beidou-2 satellite positioning system covering the whole world. The navigation system already has positioning, navigation, timing services and short message communication services in China and surrounding areas.

The antenna is a key component of the satellite navigation system, and the quality of the antenna directly affects the performance of the satellite navigation system. With the continuous advancement of satellite technology, people's demand for antennas is developing towards miniaturization, broadband and multi-frequency. For the Beidou satellite navigation and positioning system, which is an active two-way ranging two-dimensional navigation, the user terminal must include a transmitter, which puts higher requirements on the Beidou terminal antenna. The Beidou satellite navigation and positioning system works in the uplink L-band (left circular polarization) and downlink S-band (right circular polarization), so the multi-frequency and circular polarization of the Beidou antenna has become the focus of research.

With the wide application of satellite navigation and positioning systems, research on the receiving antennas of satellite navigation and positioning systems is emerging in an endless stream. At present, the commonly used satellite terminal antennas include monopole antennas, dipole antennas, quadrilateral helical antennas, helical antennas and microstrip antennas. Microstrip antenna has been widely used in mobile communication, satellite communication, missile telemetry, etc. Many fields such as Pule radar have been widely used (J.R.James and P.S.Hall.Handbook of Microstrip Antennas[M].Peter Peregrinus Ltd.(IEE),London,1989:71-81; I.J.BAHL,P.BHARTIA.Microstrip Antennas [M]. Artech House (Dedham, Mass.), 1980:60-71). The shape of the microstrip antenna radiation patch is one of the important factors affecting the performance of the antenna, which directly affects the bandwidth, frequency, gain and polarization of the antenna.

Contents of the invention

The purpose of the present invention is to provide a Beidou system with a "swastika" arm with a novel structure, flexible control, low return loss, high gain, circular polarization, and low interference between receiving and transmitting signal channels, which can be used in the Beidou system's transceiver frequency band Rectangular slotted dual-band microstrip antenna with closed-loop coupling regulation.

The invention is provided with a dielectric substrate, a rectangular patch is arranged on the upper surface of the dielectric substrate, rectangular slots are symmetrically opened at the midpoints of the four sides of the rectangular patch, and the coupling arm is vertically connected to the center of each wide side of the slot, extending to the outer edge of the rectangle and reversed. The hour hand is bent to form a "swastika" arm for loading, and the loading end forms a capacitive coupling closed loop with the outer edge of the rectangular antenna; the "swastika" arm is composed of two rectangular straight arms with similar dimensions, and the included angle is 90°; the upper and lower rectangular slots The length of the length and the length of each rectangular straight arm of the connected folding arm is 0.1mm longer than the length of the left and right rectangular slots and the length of each rectangular straight arm of the folding arm; a grounding plate is provided on the lower surface of the dielectric substrate.

The side length of the rectangular patch can be 10-30mm, the length of the rectangular slot on each side of the rectangular patch can be 4-16mm, and the width can be 2-6mm; the length of the rectangular straight arm can be 6.5-12mm, and the width It can be 0.5-3 mm.

The dielectric constant of the dielectric substrate can be 6-20, preferably 10, the dielectric substrate can be a rectangular substrate, the side length of the rectangular substrate can be 40-60mm, and the thickness can be 2-4mm, preferably the side length is 50mm, The thickness is 3mm.

The invention utilizes the loading and slotting technology, adds perturbation, changes the current distribution on the surface of the radiation patch, changes the field distribution of different natural modes of the patch, interferes with its resonant frequency, and then adjusts the position of the feed point to excite and separate two Orthogonally polarized degenerate modes to achieve dual-frequency circular polarization. By slotting and loading the size of the structure, the working frequency of the antenna can be guaranteed to meet the uplink and downlink frequency band requirements and circular polarization requirements of the Beidou satellite navigation and positioning system.

Through the loading technology of the present invention, the magnitude of the equivalent magnetic current corresponding to the electric field generated in the far-field region can be increased, thereby increasing the gain of the antenna at the zenith. And by changing the symmetry of the slot and the loading arm, increasing the side lengths of the upper and lower straight arms and the slot, causing perturbation to the patch, so as to realize the dual-frequency circular polarization characteristic.

Compared with conventional microstrip antennas, the present invention has the following advantages:

1. Easy to achieve circular polarization. Due to the use of loading and slotting technology, by loading the four "swastika" arm structures and the symmetry of the slotting, four currents are formed at 90° to each other, and the feeding position is set to produce orthogonal polarization with a phase difference of 90° degenerate mode, so as to realize the circular polarization of the antenna.

2. It is easy to realize the dual frequency characteristic. By adjusting the loaded "Swastika" arm structure, the size of the slot and the center patch, a dual-frequency working frequency band is formed: L frequency band and S frequency band, the L frequency band is 1.615-1.625GHz, the absolute bandwidth is 10MHz, and the relative bandwidth is 0.62 %; the S frequency band is 2.487-2.499GHz, the absolute bandwidth is 12MHz, and the relative bandwidth is 0.44%.

3. It is easy to realize the miniaturization of the antenna. One is the use of a high dielectric constant substrate, which reduces the size of the microstrip patch antenna. Second, the slotting technology is adopted to reduce the size of the antenna. The third is to load the curved four "Swastika" arm structure, and further reduce the size of the antenna by bending the loading arm.

In summary, the present invention has excellent comprehensive characteristics such as high symmetry, high integration, miniaturization, good radiation characteristics, and high gain, and is low in cost and easy to integrate, which can meet the requirements of the Beidou satellite navigation and positioning system for antennas.

Description of drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention.

Fig. 2 is a schematic side view of an embodiment of the present invention.

Fig. 3 is a return loss (S11) performance diagram of an embodiment of the present invention. Among them, the abscissa represents the frequency Frequency (GHz), and the ordinate represents the return loss intensity The return loss of the Antenna (dB); the coordinates in the figure are rectangular coordinates.

FIG. 4 is an E plane pattern in the L frequency band according to an embodiment of the present invention. The coordinates in the figure are polar coordinates.

Fig. 5 is an H plane pattern in the L frequency band according to the embodiment of the present invention. The coordinates in the figure are polar coordinates.

FIG. 6 is an E-plane pattern in the S-band according to an embodiment of the present invention. The coordinates in the figure are polar coordinates.

FIG. 7 is an H plane pattern in the S frequency band according to the embodiment of the present invention. The coordinates in the figure are polar coordinates.

Detailed ways

The following embodiments will further illustrate the present invention in conjunction with the accompanying drawings.

1 and 2, the embodiment of the present invention adopts a rectangular ceramic dielectric substrate 1 with a dielectric constant of 10, each side length is 50mm, and the height is 3mm. Both sides of the ceramic dielectric substrate 1 are coated with copper, and the upper surface thereof is a copper clad layer 2 loaded with slots, and its basic shape is rectangular. In the center of the copper-clad layer 2, rectangular slots are symmetrically opened at the midpoints of the four sides of the rectangular patch, and the sizes and lengths of the upper and lower rectangular slots are slightly different from those of the left and right rectangular slots. The relevant parameters of the rectangular slots are as follows: the length of the upper and lower rectangular slots is 5.10mm±0.10mm, the length of the left and right rectangular slots is 5.00mm±0.10mm, and the width of the four rectangular slots is 3mm±0.5mm. At the same time, the center of the wide side perpendicular to each side of the rectangular patch is loaded with a "swastika" arm structure. The "swastika" arm can be composed of two rectangular straight arms of similar size, and the included angle is generally 90°. Wherein, the length of the upper and lower rectangular straight arms is 8.40mm±0.10mm, the length of the left and right rectangular straight arms is 8.31mm±0.10mm, and the width of each straight arm is 1mm±0.5mm. The lower surface of the ceramic dielectric substrate 1 is a ground plate 3 covered with copper layers, which serves as a reflector for the microstrip antenna. Mark 4 in Figure 1 is the feed point, which is a hollow cylinder with a radius of 0.5mm±0.1mm and a height of 3mm±0.1mm passing through the ceramic dielectric substrate. In the present invention, the eccentric feeding form of the copper axis is adopted, as shown in FIG. 2 , this feeding form makes the S11 of the antenna lower and the gain increased. Wherein, the inner core of the copper axis is connected to the rectangular patch 2 through the feed hole, and the outer core of the copper axis is connected to the ground plate 3 on the lower surface of the ceramic dielectric board.

Referring to Fig. 3, as can be seen from Fig. 3, the working frequency band of antenna of the present invention is 1.615～1.625GHz and 2.487～2.499GHz, and the return loss (S11) of antenna in these two working frequency bands is all below-10dB, The minimum return loss in the L-band is -23.6884dB, and the minimum return loss in the S-band is -17.2145dB. It shows that the return loss performance of the antenna in these two working frequency bands all meet the required indicators. The absolute bandwidth and the relative bandwidth of the antenna of the present invention in the L frequency band are respectively: 10MHz and 0.62%; the absolute bandwidth and the relative bandwidth in the S frequency band are respectively: 12MHz and 0.44%, so it can be well applied in the Beidou satellite navigation and positioning system .

Refer to Figures 4 to 7, where Figures 4 and 5 are the E-plane and H-plane pattern diagrams of the 1.616GHz frequency point, and Figures 6 and 7 are the E-plane and H-plane pattern patterns of the 2.492GHz frequency point. It can be seen from the figure that the invention has directional radiation characteristics, can meet the requirements of the Beidou satellite navigation and positioning system, and has superior radiation performance.

Referring to Table 1, the influence of the manufacturing process error of the present invention on the two operating frequency points of the antenna characteristics is given.

Table 1

Note: The data in the table has certain redundancy, and there is a certain correlation between each parameter, and the given is the equilibrium characteristic, and the special design can be completed by optimizing the structural parameters according to the demand.

The manufacturing and processing errors of the present invention have a great influence on the parameters of the antenna, requiring a very fine manufacturing process. For example, the size of the patch, the length and width of the slot, the distance between the slot and each side, the size of the ceramic dielectric substrate, the thickness of the metal-coated good conductor layer of the dielectric board, and the position of the feed point are controlled within 2%. When the relative permittivity error of the substrate is controlled within 5%, the parameters of the antenna do not change much.

Claims (9)

1. The rectangular slotted dual-frequency microstrip antenna with Swastika arm closed-loop coupling control of the Beidou system is characterized in that it is provided with a dielectric substrate, and a rectangular patch is arranged on the upper surface of the dielectric substrate, which is symmetrically opened at the midpoint of the four sides of the rectangular patch. There are rectangular slots, the coupling arm is vertically connected at the center of the wide side of each slot, and then bent counterclockwise after extending to the outer edge of the rectangle to form a "swastika" arm loading, and the loading end forms a capacitive coupling closed loop with the outer edge of the rectangular antenna; "Swastika" The word arm is composed of two rectangular straight arms with similar dimensions, and the included angle is 90°; the length of the upper and lower rectangular slots and the length of each rectangular straight arm of the connected folding arms are more than the length of the left and right rectangular slots and the length of each rectangular straight arm of the folding arms The length is 0.1 mm long; a ground plate is provided on the lower surface of the dielectric substrate. 2. The rectangular slotted dual-frequency microstrip antenna of Beidou system with swastika arm closed-loop coupling regulation as claimed in claim 1, characterized in that the side length of the rectangular patch is 10-30mm. 3. as claimed in claim 1, the Beidou system has a rectangular slotted dual-frequency microstrip antenna with swastika arm closed-loop coupling regulation, wherein the length of each side rectangular slot of the rectangular patch is 4 to 16 mm, and the width is 2 ~ 6mm. 4. The rectangular slotted dual-frequency microstrip antenna with swastika arm closed-loop coupling control of the Beidou system according to claim 1, characterized in that the length of the rectangular straight arm is 6.5-12 mm, and the width is 0.5-3 mm. 5. The rectangular slotted dual-band microstrip antenna with swastika arm closed-loop coupling regulation of the Beidou system according to claim 1, characterized in that the dielectric constant of the dielectric substrate is 6-20. 6. The rectangular slotted dual-band microstrip antenna with swastika arm closed-loop coupling control of the Beidou system according to claim 5, wherein the dielectric constant of the dielectric substrate is 10. 7. The rectangular slotted dual-band microstrip antenna with swastika arm closed-loop coupling regulation of the Beidou system according to claim 1, wherein the dielectric substrate is a rectangular substrate. 8. The rectangular slotted dual-band microstrip antenna with swastika arm closed-loop coupling regulation of the Beidou system according to claim 7, characterized in that the side length of the rectangular substrate is 40-60 mm, and the thickness is 2-4 mm. 9. The rectangular slotted dual-frequency microstrip antenna of the Beidou system with swastika arm closed-loop coupling regulation as claimed in claim 8, wherein the side length of the rectangular substrate is 50mm and the thickness is 3mm.

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