CN103633444B - Coupled array microstrip antenna for Beidou navigation system - Google Patents

Abstract

A coupled array microstrip antenna for a Beidou navigation system relates to a microstrip antenna. Provides a high gain, low elevation angle, small size, low axial ratio, high phase center stability, a coupled array microstrip antenna for the Beidou navigation system in the Beidou downlink S-band. There is a single-sided copper-clad substrate, a square copper conductor surface antenna patch is provided on the single-sided copper-clad layer substrate, and a rectangular coupling array is arranged around the square copper conductor surface antenna patch, and the square copper conductor surface antenna patch There are symmetrically distributed outer layer slots, middle layer slots and inner layer slots inside; feeding holes are provided on the antenna patch on the square copper conductor surface.

Description

Coupled array microstrip antenna for Beidou navigation system

technical field

The invention relates to a microstrip antenna, in particular to a coupled array microstrip antenna for a Beidou navigation system.

Background technique

Beidou Satellite Navigation System﹝BeiDou (COMPASS) Navigation Satellite System﹞is a self-developed and independently operated global satellite navigation system being implemented in China. It is the fourth mature satellite navigation system after GPS, GLONASS, and GALILEO. The system is committed to providing high-quality positioning, navigation, timing and communication services to global users. According to the plan, the Beidou satellite navigation system will provide official services to most parts of the Asia-Pacific region in early 2013. Around 2020, the Beidou satellite navigation system will form a global coverage capability. The Beidou satellite navigation system consists of three parts: the space segment, the ground segment and the user segment. The space segment includes 5 geostationary orbit satellites and 30 non-geostationary orbit satellites. The ground segment includes several ground stations such as the main control station, the injection station and the monitoring station. , the user segment includes Beidou user terminals and terminals compatible with other satellite navigation systems. The Beidou system has been widely used in transportation, fishery, hydrology, meteorology, forestry, communication, electric power, rescue and many other fields. The number of registered users has reached 60,000, which has produced significant social and economic benefits. It will become a new growth point of the national economy, and will have a profound impact on improving the level of social informatization, promoting sustainable economic development, improving people's quality of life, enhancing public security and national defense security, and has great strategic significance .

Because Beidou satellites use geosynchronous satellites and are relatively far from the earth's surface, the Beidou satellite signals reaching the ground are very weak. At the same time, the Beidou satellite transmitting antenna array is a shaped beam, and the beam signal with a low elevation angle has a greater contribution to the positioning accuracy, thus requiring a certain elevation angle. In general, the terminal antenna has the following requirements:

1. Phase pattern and phase center. In the Beidou satellite positioning system, due to the phase difference of the antenna output terminals at different angles on the satellite, a certain positioning error will occur, which is unacceptable for users with high precision requirements. Therefore, for the area where the satellite provides services, the antenna should provide Uniform magnitude and phase response. The stability of the phase center of the antenna is related to the form of the antenna and the feeding method. Generally speaking, the better the symmetry of the antenna, the higher the stability of its phase center. The antenna ensures the stability of the phase center of the antenna from the design.

2. Amplitude pattern and gain. During the working process of the navigation and positioning system, if the pitch angle of the satellite is lower than the specified value, the receiver antenna will not receive the signal. At the same time, in order to avoid serious tropospheric effects and multipath effects as much as possible, the directional gain in the effective angle of the antenna is increased. For Beidou navigation satellites, it is required to increase the low elevation gain of the antenna, that is, a pattern with a wider beamwidth.

3. Frequency and polarization. At present, the existing satellite navigation systems have different operating frequencies, but all require the polarization characteristics to be circular polarization. my country's Beidou satellite navigation system works in the uplink L frequency band (where the working frequency point L1: 1610-1626.5MHz, the compensation frequency point L2: 1227.6MHz), this frequency band adopts left-handed circular polarization; the downlink S frequency band (where the working frequency point: 2483.5 -2500MHz), this frequency band adopts right-handed circular polarization. However, for more accurate positioning, in order to compensate for the delay caused in the ionospheric propagation process, dual-frequency or multi-frequency operation is generally used. Therefore, it is required that the terminal antenna has good working performance at each frequency.

To sum up, in the design process of the Beidou satellite navigation system terminal receiving antenna, the following requirements should be considered accordingly: the frequency of the terminal receiving antenna should fall within the frequency band of the Beidou satellite navigation system; the antenna polarization characteristic is circular Polarization, so that it can receive Beidou satellite signals from any polarization and any direction in the sky.

As a new type of antenna, microstrip antenna has irreplaceable advantages compared with ordinary antenna. It has the characteristics of small size, light weight, simple planar structure, easy to achieve circular polarization and dual frequency; in addition, microstrip antenna also has the characteristics of compact structure, stable performance, easy-to-use printed circuit technology and mass manufacturing technology.

For most of the microstrip circularly polarized antennas currently working, the size of conventional microstrip circularly polarized antennas is generally relatively large. Circular polarization characteristics, such as axial ratio, elevation angle, etc. are too large, making it difficult for the antenna to achieve the best performance.

According to the data, no one has applied array coupling technology and phase center stable design to the design of Beidou antenna.

Contents of the invention

The object of the present invention is to provide a high gain, low elevation angle, small size, low axial ratio, high phase center stability, and a coupled array microstrip antenna for the Beidou navigation system in the Beidou downlink S-band.

The invention is provided with a single-sided copper-clad layer substrate, a square copper conductor surface antenna patch is arranged on the single-sided copper-clad layer substrate, and a rectangular coupling array is arranged around the square copper conductor surface antenna patch. The patch is provided with symmetrically distributed outer layer grooves, middle layer grooves and inner layer grooves; a feed hole is arranged on the square copper conductor surface antenna patch.

The single-sided copper-clad substrate can be a composite ceramic dielectric board with a relative dielectric constant of 9.8±5%. The length of the single-sided copper clad substrate may be 25.32±0.01mm, the width may be 25.32±0.01mm, and the thickness may be 3±0.01mm.

The size of the square copper conductor surface antenna patch can be 15.99±0.01mm×2.67±0.01mm, wherein both sides are cut corners, and the length is 2.26±0.01mm.

The size of the rectangular coupling array can be 15.99±0.01mm×15.99±0.01mm, the distance between the rectangular coupling array and the antenna patch on the square copper conductor surface is 1.07±0.01mm; the size of the outer groove can be 9.14±0.01mm× 0.80±0.01mm; the middle groove is a bending groove, the arm length of the middle groove can be 4.81±0.01mm, the two arms are equal in length, the distance between the middle groove and the outer groove can be 0.86±0.01mm, the outer groove and the square copper The edge distance of the conductor surface antenna patch can be 0.73±0.01mm; the size of the inner groove can be 5.33±0.01mm×0.80±0.01mm, and the distance between the inner groove and the middle groove can be 0.81±0.01mm.

The size of the feed hole may be 0.5±0.01mm, and the height may be 3±0.01mm. The center distance between the feed hole and the antenna patch on the square copper conductor surface may be 2.65±0.01mm.

The present invention adopts copper axis offset feed to feed power, which makes the S11 of the antenna lower and the gain increased. Wherein, the inner core of the copper axis is connected with the rectangular patch on the upper surface through the feed hole, and the outer core of the copper axis is connected with the reflection plate on the lower surface of the composite ceramic dielectric plate.

The size of the present invention can be designed to be 25.32mm±0.1mm×25.3±0.1mm, which is 10% of the size of a common microstrip antenna, and achieves the purpose of miniaturizing the Beidou antenna. At the same time, the present invention has very good low-elevation angle characteristics, the central frequency axial ratio is 1.2, the 3dB axial ratio bandwidth reaches 15MHz, and the return loss (S11) of the central frequency can reach below -35dB. The invention can completely put it in the Beidou navigation terminal, and has the advantages of simple structure, low cost, good performance, easy integration and the like. The two main features of the present invention are: one is to use array coupling to achieve the purpose of low elevation angle, and the other is to use slotting technology and high dielectric constant substrate to achieve the purpose of miniaturization, so that the overall antenna size is only about 25mm.

The present invention is mainly composed of two parts, one is the main patch, which mainly generates the radiation of the corresponding frequency; the other is the coupling array, which mainly adjusts the elevation angle performance of the main patch. The main patch adopts a square cut corner structure to generate circular polarization, and uses slotting technology to reduce the size of the antenna.

The array coupling technology adopted in the present invention makes the elevation angle of the antenna smaller, and the gain of the antenna at 0 and 90° is close to that of a hemisphere, and has good low elevation angle performance. At the same time, slots are made on the patch to form a slot array. to reduce the size of the antenna. Compared with the existing circularly polarized microstrip antenna, the array coupling structure adopted by the present invention can well improve the elevation angle performance of the antenna. Applying the coupled array mechanism to the microstrip patch antenna can improve the antenna's radiation characteristics in the half-plane and suppress its radiation in the lower half-plane. Moreover, a symmetrical structure is adopted, and the width of the grooves in each layer is also the same size, so the present invention has a high phase center stability. The present invention can also be extended to other antennas in engineering applications, and has important significance for engineering applications.

Description of drawings

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

Fig. 2 is a performance diagram of the return loss (S11) of the present invention.

Fig. 3 is an axial ratio diagram of the present invention within a frequency band.

Fig. 4 is the E-plane and H-plane gain pattern of the present invention at 2.492 GHz. In Figure 4, curve a is E plane and curve b is H plane.

Detailed ways

The following embodiments will further illustrate the technical solutions and outstanding effects of the present invention in conjunction with the accompanying drawings.

Referring to Figures 1 to 3, the embodiment of the present invention is provided with a single-sided copper-clad substrate 1, on which a square copper conductor surface antenna patch 3 is provided, and around the square copper conductor surface antenna patch 3 A rectangular coupling array 2 is provided, and outer layer slots 4, middle layer slots 5 and inner layer slots 6 are arranged symmetrically in the square copper conductor surface antenna patch 3; Hole 7.

The single-sided copper-clad substrate 1 adopts a composite ceramic dielectric board with a relative dielectric constant of 9.8±5%. The length of the single-sided copper-clad substrate 1 is 25.32±0.01mm, the width is 25.32±0.01mm, and the thickness is 3±0.01mm.

The size of the square copper conductor surface antenna patch 3 is 15.99±0.01mm×2.67±0.01mm, and the two sides are cut corners, and the length is 2.26±0.01mm.

The size of the rectangular coupling array 2 is 15.99±0.01mm×15.99±0.01mm, and the distance between the rectangular coupling array 2 and the square copper conductor surface antenna patch 3 is 1.07±0.01mm; the size of the outer slot 4 is 9.14±0.01mm mm×0.80±0.01mm; the middle groove 5 is a bending groove, the arm length of the middle groove 5 is 4.81±0.01mm, the two arms are equal in length, the distance between the middle groove 5 and the outer groove 4 is 0.86±0.01mm, the outer The distance between the slot 4 and the antenna patch 3 on the square copper conductor surface is 0.73±0.01mm; the size of the inner slot 6 is 5.33±0.01mm×0.80±0.01mm, and the distance between the inner slot 6 and the middle slot 5 is 0.81± 0.01mm.

The size of the feed hole 7 is 0.5±0.01mm, and the height is 3±0.01mm. The center distance between the feed hole 7 and the antenna patch 3 on the square copper conductor surface is 2.65±0.01mm.

In the present invention, copper axis offset feed is used for feeding, and this feeding form makes the S11 of the antenna lower and the gain increased. Wherein, the inner core of the copper axis is connected with the rectangular patch on the upper surface through the feed hole, and the outer core of the copper axis is connected with the reflection plate on the lower surface of the composite ceramic dielectric plate.

It can be seen from FIG. 2 that the working frequency band of the present invention may be 2.47-2.52 GHz. The return loss (S11) of the antenna in this working frequency band is below 10dB, and the minimum return loss at 2.51GHz is -35dB. It can be seen from the above that the return loss performance of the antenna in the entire passband can meet the requirements. The absolute bandwidth and relative bandwidth of the present invention at 2.492GHz are 55M and 2.1% respectively; the performance is stable and can directional radiation, so it can be well applied in satellite communication systems such as Beidou and GPS.

Referring to Fig. 3, the present invention has good axial ratio performance in the Beidou navigation downlink frequency band of 2.487-2.497 GHz, all of which are below 3dB.

Referring to Fig. 4, it is the direction diagram of the E plane and the direction diagram of the H plane. It can be seen from Fig. 4 that the present invention has directional radiation characteristics and can meet the requirements of the satellite communication system. At the same time, it can also be seen that the antenna reaches ±60° in the direction of 0dB, has very good low elevation angle characteristics, and the elevation angle performance is very good. At the same time, if the size of the dielectric plate is increased, the directional gain of the antenna can be increased.

See Table 1 for the influence of manufacturing processing errors on antenna characteristics in the present invention.

Table 1

To sum up, the present invention adopts the array coupled microstrip antenna technology to design the antenna. It can be seen from the return loss (S11) performance diagram of the antenna that the antenna has already covered the frequency band of 2.474-2.529 GHz, and has reached the Beidou uplink S frequency band. Require. It can be seen from the simulated radiation pattern and the E-plane pattern and the H-plane pattern that the antenna has very good low elevation angle characteristics.

Claims (7)

1. The coupled array microstrip antenna for the Beidou navigation system is characterized in that a single-sided copper-clad substrate is provided, and a square copper conductor surface antenna patch is arranged on the single-sided copper-clad layer substrate. There is a rectangular coupling array around the patch, and there are symmetrically distributed outer layer slots, middle layer slots and inner layer slots in the square copper conductor surface antenna patch; feed holes are provided on the square copper conductor surface antenna patch; The size of the outer groove is 9.14±0.01mm×0.80±0.01mm; the middle groove is a bending groove, the arm length of the middle groove is 4.81±0.01mm, the two arms are equal in length, and the distance between the middle groove and the outer groove is 0.86 ±0.01mm, the distance between the outer groove and the edge of the antenna patch on the square copper conductor surface is 0.73±0.01mm; the size of the inner groove is 5.33±0.01mm×0.80±0.01mm, and the distance between the inner groove and the middle groove is 0.81 ±0.01mm. 2. The coupled array microstrip antenna for the Beidou navigation system according to claim 1, wherein the single-sided copper-clad substrate adopts a composite ceramic dielectric plate with a relative permittivity of 9.8±5%. 3. The coupled array microstrip antenna for Beidou navigation system as claimed in claim 1 or 2, characterized in that the length of the single-sided copper clad substrate is 25.32 ± 0.01mm, the width is 25.32 ± 0.01mm, and the thickness is 3±0.01mm. 4. The coupled array microstrip antenna for Beidou navigation system as claimed in claim 1, characterized in that the size of the square copper conductor surface antenna patch is 15.99 ± 0.01mm × 2.67 ± 0.01mm, wherein both sides are cut corners , the length is 2.26±0.01mm. 5. The coupled array microstrip antenna for Beidou navigation system as claimed in claim 1, characterized in that the size of the rectangular coupled array is 15.99 ± 0.01mm × 15.99 ± 0.01mm, and the rectangular coupled array and the square copper conductor surface antenna The distance between the patches is 1.07±0.01mm. 6. The coupled array microstrip antenna for Beidou navigation system according to claim 1, characterized in that the size of the feeding hole is 0.5±0.01mm, and the height is 3±0.01mm. 7. The coupled array microstrip antenna for Beidou navigation system according to claim 1 or 6, characterized in that the center distance between the feeding hole and the square copper conductor surface antenna patch is 2.65±0.01mm.