CN106532248A - Ultra-compacted microstrip patch array antenna - Google Patents

Abstract

The invention discloses an ultra-compact microstrip patch array antenna, which includes a dielectric board, an antenna array and a metal floor; wherein the antenna array and the metal floor are arranged on the dielectric board; wherein the antenna array is composed of more than two antenna array units, Each antenna array unit includes a feeder and a radiation patch; a decoupling network is provided between the radiation patches of every two antenna array units, and a certain gap is left between the decoupling network and the two radiation patches ; Each decoupling network is an interdigitated structure formed by two mutually inserted left and right combs. The invention can greatly reduce the electromagnetic mutual coupling between the arrays while ensuring the excellent bandwidth performance of the antenna unit, and achieve miniaturization of the antenna on the basis of ensuring a certain performance, thereby realizing the ultra-compact structure of the array antenna.

Description

An ultra-compact microstrip patch array antenna

technical field

The invention relates to the technical field of antennas, in particular to an ultra-compact microstrip patch array antenna.

Background technique

With the development of modern wireless communication systems, wireless terminals have been developing in the direction of miniaturization. For microstrip array antennas installed in mobile device terminals, we have to adapt to this limited space by reducing the unit size or reducing the spacing between units. However, the reduction of the distance between the elements of the array antenna has the most direct impact on the increase of the coupling between the antenna elements. The energy of a unit can generate mutual coupling with the surrounding array elements through media such as dielectric plates and free space. The existence of this mutual coupling will have a series of effects on the radiation performance of the antenna array, such as pattern distortion, resonance point shift, and signal-to-noise ratio reduction.

At present, the work of reducing the mutual coupling between antenna arrays is mainly analyzed from two aspects: 1, by changing the geometric structure of the antenna itself or the arrangement of the array elements to reduce the coupling between the antenna elements; Additional structures are loaded between the radiation patches to form a forbidden band for electromagnetic wave transmission, thereby achieving mutual coupling suppression. However, these methods are difficult to achieve ultra-compact antenna arrays (eg, the distance between adjacent patches is smaller than λ/10).

In addition, to realize the miniaturization of the overall structure of the antenna, the size of the feed network should be compressed correspondingly to the size of the radiation patch array. Usually, in order to realize equal-amplitude and in-phase feeding, the feeding network of the array antenna acts as a dual function of a power divider and a phase shifter. The phase shifter in the traditional sense is usually realized by the method of phase accumulation, which is not conducive to the miniaturization of the antenna system.

Contents of the invention

The technical problem to be solved by the invention is that the existing array antenna has the problems of large size and poor unit isolation, and an ultra-compact microstrip patch array antenna is provided.

In order to solve the above problems, the present invention is achieved through the following technical solutions:

An ultra-compact microstrip patch array antenna, including a dielectric board, an antenna array and a metal floor; wherein the antenna array and the metal floor are set on the dielectric board; wherein the antenna array is composed of more than two antenna array units, and each antenna The array unit includes a feeder line and a radiation patch; a decoupling network is provided between the radiation patches of every two antenna array units, and there is a certain gap between the decoupling network and the two radiation patches; each The decoupling network is an interdigitated structure composed of two mutually inserted left and right combs; the left and right combs have the same structure and are independent of each other; the left and right combs The teeth are all composed of knuckle connecting line and two or more knuckles located on the same side of the knuckle connecting line, and the extension direction of the knuckles is perpendicular to the extending direction of the knuckle connecting line; the knuckle of the left comb is located on the knuckle connecting line the right side of the comb; the knuckles of the right comb are on the left side of the knuckle connecting line.

In the above solution, the knuckles of the left comb teeth and the knuckles of the right comb teeth of each decoupling network are alternately arranged at intervals.

In the above solution, the length of the connecting line of knuckles is longer than the length formed after all knuckles are arranged side by side.

In the above solution, the decoupling network and the radiation patch are located on the same layer of the dielectric board.

In the above solution, the feeder is a microstrip feeder, a back feeder or a bottom feeder.

In the above scheme, at least one composite left-handed phase-shifting unit is provided on the feeder of the antenna array unit; each composite left-handed phase-shifting unit is composed of interdigitated capacitors, microstrip lines and metal vias; interdigitated capacitors are arranged in series on the feeder , the metal via is arranged near the feeder, and the interdigitated capacitor and the metal via are connected through a microstrip line.

In the above solution, the number of composite left and right hand phase shifting units on different feeders changes sequentially.

In the above solution, at least one T-junction is provided between the feeder and the feeder of the antenna array unit.

Compared with prior art, the present invention has following characteristics:

1. For antenna arrays with different working frequency bands, the isolation between array elements can be improved by adjusting the size parameters of the decoupling network;

2. Using the proposed structure to reduce the electromagnetic mutual coupling between the array elements, the distance between the array elements can be compressed to less than 0.08 times the wavelength to achieve the purpose of miniaturization;

3. The use of composite left and right-handed transmission line phase shifters can solve the problem that the phase shifters made of traditional bent lines occupy a large space.

Description of drawings

FIG. 1 is a schematic diagram of a three-dimensional structure of an ultra-compact microstrip patch array antenna.

Figure 2 is a schematic diagram of a decoupling network.

FIG. 3 is a schematic diagram of a composite left and right hand phase shifting unit.

Figure 4 is a comparison of the reflection coefficient S11 and the coupling coefficient S21 of the array antenna with the decoupling network loaded and the unloaded decoupling network (the dotted line is the simulation, and the solid line is the actual measurement); (a) is the antenna array without the decoupling network loaded, ( b) Antenna array for loading and decoupling network.

Fig. 5 is an ultra-compact microstrip patch array antenna and a miniaturized feed network overall S-parameter simulation and actual measurement comparison diagram (the dotted line is the simulation, the solid line is the actual measurement).

Figure 6 is an ultra-compact microstrip patch array antenna and the overall normalized far-field pattern of the miniaturized feed network (the dotted line is the simulation, the solid line is the actual measurement); (a) is the H surface, (b) For the E side.

Labels in the figure: 1, dielectric board; 2-1, knuckle; 2-2, knuckle connection line; 3-1, feeder line; 3-2, radiation patch; 4, T-junction; 5-1, alternating current Refers to capacitance; 5-2 microstrip line; 5-3, metal via; 6, metal floor.

detailed description

An ultra-compact microstrip patch array antenna, as shown in Figure 1, consists of a dielectric plate 1, an antenna array, a metal floor 6, a decoupling network and a feed network.

The dielectric board 1 serves as the carrier of the entire microstrip patch array antenna, on which an antenna array, a metal floor 6, a decoupling network and a feeding network are arranged. In the present invention, the antenna array, the decoupling network and the feeding network are located on the upper surface of the dielectric board 1 , and the metal floor 6 is located on the lower surface of the dielectric board 1 . The shape and size of the dielectric board 1 are determined according to the shapes and sizes of the carried antenna array, decoupling network and feed network. In a preferred embodiment of the present invention, the shape of the dielectric board 1 is a convex shape, wherein the upper area of the convex shape is smaller and the feeding network is set, and its size is 108 mm × 23 mm. The lower area of the convex shape is larger and the antenna is set. The size of the array is 150mm x 80mm in length x width. The thickness of the dielectric plate 1 is 0.8mm, the relative permittivity is 4.4, and the loss tangent is 0.02.

The metal floor 6 is a covering metal layer printed on the dielectric board 1 . In a preferred embodiment of the present invention, the metal floor 6 completely covers the lower surface of the dielectric board 1 . The metal floor 6 interacts with the radiation patch 3-2 of the antenna array unit, and the two together form a two-wire structure to ensure the normal operation of the antenna.

The antenna array is composed of more than two antenna array units, which are metal structural layers printed on the dielectric board 1. Each antenna array unit has the same structure and is independent of each other, that is, there is a certain distance between the two antenna array units. Pitch. In a preferred embodiment of the present invention, the number of antenna array units is three. The size of the antenna array unit is determined by the dielectric constant, loss tangent, thickness and antenna operating frequency of the dielectric board 1 . In the present invention, each antenna array unit is composed of a feeder 3-1 and a radiation patch 3-2, the radiation patch 3-2 needs to be covered on the surface of the dielectric board 1, and the feeder 3-1 can be in the form of an external connection (such as back-feed or bottom-feed), can also adopt the form of covering on the surface of the dielectric plate 1 . The radiation patch 3-2 is directly or coupled to the feeder 3-1. In a preferred embodiment of the present invention, both the radiation patch 3-2 and the feeder 3-1 are covered on the surface of the dielectric plate 1, the shape of the radiation patch 3-2 is rectangular, and the feeder 3-1 is a long strip The microstrip feeder 3-1 and the radiation patch 3-2 are directly connected to the feeder 3-1.

In order to reduce the mutual influence between the antenna array units in a limited size, the present invention is provided with a decoupling network between the radiation patches 3-2 of every two antenna array units, and the decoupling network and the two radiation patches A certain gap is left between the patches 3-2. The decoupling network suppresses electromagnetic waves, but is not limited by the feeding form. Referring to FIG. 2 , each decoupling network is an interdigitated structure formed by two mutually inserted left and right combs. Wherein the structures of the left comb teeth and the right comb teeth are the same, and the two are independent of each other. Described left comb tooth and right comb tooth are all made of knuckle connection line 2-2 and more than 2 knuckles 2-1 that are positioned at the same side of knuckle connection line 2-2, and the extension direction of knuckle 2-1 and The extension direction of the knuckle connecting line 2-2 is vertical, and the length of the knuckle connecting line 2-2 is longer than the length formed by all the knuckles 2-1 arranged side by side. The knuckle 2-1 of the left comb tooth is located on the right side of the knuckle connecting line 2-2; the knuckle 2-1 of the right comb tooth is located on the left side of the knuckle connecting line 2-2. The left comb teeth and the right comb teeth can be inserted in a whole or alternately. In the present invention, the left comb teeth and the right comb teeth are inserted alternately, that is, the knuckles 2-1 of the left comb teeth and the knuckles 2-1 of the right comb teeth of each decoupling network are alternately arranged at intervals. The decoupling network is a resonant structure composed of interdigitated knuckles 2-1, which can be adjusted in a limited space by adjusting the corresponding size (including knuckles 2-1 number N, width n, spacing g ₂ and connecting lines on both sides length L _res , etc.), to regulate the transmission characteristics of electromagnetic waves on the surface of the structure. Under the parameters of certain specific structures, the purpose of decoupling in the working frequency band of the antenna is achieved.

In order to provide an appropriate power distribution ratio and phase relationship so that the antenna as a whole has a required radiation pattern, the present invention also provides a feed network, which includes a composite left and right hand phase shifting unit and a T-junction 4 . The composite left and right hand phase shifting unit is used to achieve phase matching between the antenna array units, and the T-junction 4 is used to adjust the power distribution ratio between the antenna array units. In order to facilitate parameter adjustment, the present invention needs to perform equal-power matching adjustment first, and then perform equal-amplitude and in-phase matching adjustment. The antenna array elements are connected.

The invention adopts the composite left and right hand phase shifting unit to realize the same-phase feeding of the antenna. In general, the realization of series in-phase feeding is that the phase delay between the radiating elements is a full wavelength, that is, the length of the transmission line between the two radiating elements is about one working wavelength. For in-phase feeding of ultra-compact antenna arrays, the size of the feeding network also needs to be reduced synchronously, which inevitably results in a distance between the feeding ports of less than one wavelength, and the use of meander lines enables the feeding through phase accumulation. The role of phase shifting between electrical network ports, but inevitably occupies a larger size. By adding the phase-shifting unit of the composite left-handed transmission line, the feed network can output electromagnetic waves in the same phase, while ensuring a compact structure. From the point of view of the analysis method of the circuit, the formation of a composite left-handed transmission line requires a series capacitance and a parallel inductance in a two-wire structure. In the present invention, the composite left and right hand phase shifting unit is arranged on the feeder line 3-1 of the antenna array unit. Referring to FIG. 3 , each composite left and right hand phase shifting unit is composed of an interdigitated capacitor 5-1, a microstrip line 5-2 and a metal via 5-3. The interdigitated capacitor 5-1 is serially arranged on the feeder 3-1, and the interdigitated structure can provide the serial capacitor in the composite left-handed transmission line. The metal via 5-3 is arranged near the feeder 3-1, the interdigitated capacitor 5-1 and the metal via 5-3 are connected through the microstrip line 5-2, and the microstrip line 5-2 passes through the metal via 5-3 Connected to the metal floor 6, a parallel inductance can be provided. By changing the relevant parameters of the interdigitated structure (including e, s, lcap, etc.) and the relevant parameters of the microstrip line 5-2 (including lind and wind), the corresponding capacitance and inductance values will be changed. According to the relevant theory of the composite left-handed transmission line, adjusting the corresponding capacitance and inductance value can change the transmission state of the electromagnetic wave along the transmission line and achieve the purpose of phase shifting. Different numbers of composite left-handed phase-shifting units are set on each feeder 3-1 according to requirements, and the number of composite left-handed phase-shifting units on different feeders 3-1 changes sequentially, that is, the composite left-handed phase-shifting units on different feeders 3-1 The change of the number of phase shifting units can be a linear increasing or a nonlinear increasing change relationship according to design requirements. In a preferred embodiment of the present invention, the antenna array unit positioned on the rightmost side of the dielectric board 1 is used as the reference of all antenna array units, and the composite left and right hand phase shifting unit is not provided on its feeder 3-1, and the antenna array unit located in the middle is provided with 1 composite left and right hand phase shifting unit, and 2 composite left and right hand phase shifting units are installed on the antenna array unit in the left.

The present invention uses the T-junction 4 for equal power distribution. There is at least one T-junction 4 between the feeder 3-1 of the antenna array unit and the feed source. The T-junction 4 actually consists of two microstrip lines, one of which has a wider width than the other. The line width of the microstrip line, thus forming a T-shape. In the preferred embodiment of the present invention, a T-junction 4 is arranged between the antenna array unit on the leftmost side of the dielectric board 1 and the feed source; There is one T-junction 4 between the antenna array units, which is equivalent to two T-junctions 4 between the antenna array unit and the feed source located in the middle of the dielectric board 1; the antenna array located on the far right side of the dielectric board 1 The unit is connected to the antenna array unit located in the middle of the dielectric board 1 through a microstrip line of equal thickness, which is equivalent to two T-junctions 4 between the antenna array unit located on the far right side of the dielectric board 1 and the feed source. The output power ratio of the three output ports of the feed network after optimized parameters is 1:1:1. The overall structure of the feed network is composed of two T-junctions 4 that divide the power into 1:2 and 1:1 respectively. The biggest advantage of T-junction 4 is to adjust the output power division ratio by changing the impedance of the input terminal and the other output terminal when the impedance of one output terminal is fixed (when other conditions remain unchanged, the line width determines the impedance). This facilitates the connection with the antenna feeder 3-1 whose impedance is 50Ω. Wherein, the change of impedance is realized by the line width. In the preferred example of the present invention, the length of the transmission line for changing the line width is a quarter wavelength, so as to be suitable for the impedance matching between the T-junction 4 and the transmission line connected thereto.

Effect of the present invention is illustrated below by a specific example:

The working center frequency of the antenna array is 2.4GHz, and the working bandwidth is greater than 30MHz. The distance between the edges of the radiating patch 3-2 is d=10mm, which is about 0.08 times the wavelength, which is the free-space wavelength at a frequency of 2.4GHz. The feeding port is located on the side of the dielectric board 1, where the dimensions of the radiation patch 3-2 are: L=30mm, W=30mm, and the width of the feeding line 3-1 is 1.53mm. Dimensions of the decoupling network: L _res =30 mm, W _res =8 mm, W _g =2.96 mm, W _s =1 mm, g1 =1 mm, g2 =0.67 mm, n=0.17 mm. The decoupling network is located between the radiation patches 3-2, but not connected to them, and is closely attached to the dielectric board 1.

The simulation and actual measurement results of the antenna's S parameters are shown in Figure 4, where Figure 4(a) is the antenna array without a decoupling network, and Figure 4(b) is the antenna array with a decoupling network loaded. It can be seen from the figure that when the antenna array operates at a frequency of 2.4GHz, after the decoupling network is loaded, the isolation S21 drops to about -40dB. In addition, when the mutual coupling is greatly reduced, the operating bandwidth of the antenna is less affected. Figure 5 and Figure 6 are the comparison diagrams of the simulation and actual measurement results in the near-field and far-field directions after loading the decoupling network and the feed network. Figure 5 is a comparison chart of S parameters. It can be seen that the preferred example of the present invention has a high degree of agreement with the simulation data in terms of near-field results; FIG. 6 is a comparison diagram of the normalized far-field H-plane and E-plane. It can be seen that for the overall antenna loaded with the decoupling network, the antenna radiation main lobe half-power wavenumber width (HPBW) width of the E plane and the H plane are 40° and 70° respectively, which basically meets the directivity requirements of the array antenna.

The present invention uses a resonant interdigitated structure decoupling network to perform decoupling between array antenna units, which can greatly reduce the electromagnetic coupling between adjacent radiation patches 3-2, while ensuring the excellent bandwidth performance of the antenna units, The electromagnetic mutual coupling between the arrays is greatly reduced, and on the basis of ensuring a certain performance, the miniaturization of the antenna is achieved, thereby realizing the ultra-compact structure of the array antenna. At the same time, the miniaturized feed network is designed by using the left and right hand transmission lines, and finally the miniaturization of the overall structure of the antenna array is realized. The invention has the advantages of compact structure, good decoupling effect, easy processing and the like.

The principles, features, functions and related advantages of the present invention have been introduced above. It should be pointed out that the above simulation cases are only used to illustrate the technical solutions of the present invention, and are not limiting. For relevant personnel in this industry, without departing from the principle of the present invention, the improvements made should also be regarded as the protection scope of the present invention. At the same time, combined with the principle of scaling, this method can still be used for electromagnetic decoupling problems in patch array antennas in other frequency bands.

Claims (8)

1. a kind of ultra-compact Section of Microstrip Antenna Array, including dielectric-slab (1), aerial array and metal floor (6)；Wherein day Linear array and metal floor (6) are arranged on dielectric-slab (1)；Wherein aerial array is made up of the antenna array unit of more than 2, Each antenna array unit includes feeder line (3-1) and radiation patch (3-2)；It is characterized in that：

A decoupling network, and the decoupling network and this 2 spokes are provided between radiation patch (3-2) per 2 antenna array units Penetrate certain gap is left between paster (3-2)；Each decoupling network is 2 left comb for plugging each other and right comb institute structure Into interdigital structure；Wherein left comb is identical with the structure of right comb, and both are separate；The left comb and right comb are equal By finger joint connecting line (2-2) and it is located at the finger joint (2-1) of more than 2 of finger joint connecting line (2-2) the same side and constitutes, finger joint (2- 1) bearing of trend is vertical with the bearing of trend of finger joint connecting line (2-2)；The finger joint (2-1) of left comb is positioned at finger joint connecting line (2-2) right side；The finger joint (2-1) of right comb is positioned at the left side of finger joint connecting line (2-2).

2. a kind of ultra-compact Section of Microstrip Antenna Array according to claim 1, it is characterised in that：Each decoupling network The finger joint (2-1) of left comb and the finger joint (2-1) of right comb alternate interval setting.

3. a kind of ultra-compact Section of Microstrip Antenna Array according to claim 1, it is characterised in that：Finger joint connecting line (2-2) length formed after being longer than all finger joints (2-1) side by side by length.

4. a kind of ultra-compact Section of Microstrip Antenna Array according to claim 1, it is characterised in that：Decoupling network and spoke Penetrate same layer of the paster (3-2) positioned at dielectric-slab (1).

5. a kind of ultra-compact Section of Microstrip Antenna Array according to claim 1, it is characterised in that：Feeder line (3-1) is Microstrip-type feeder line (3-1), back feed type feeder line (3-1) or bottom feedback formula feeder line (3-1).

6. a kind of ultra-compact Section of Microstrip Antenna Array according to claim 1, it is characterised in that：Antenna array unit Feeder line (3-1) be provided with least one composite left-and-right-hand phase-shifting unit；Each composite left-and-right-hand phase-shifting unit is by interdigital capacitor (5-1), trickle band wire (5-2) and metallic vias (5-3) composition；Interdigital capacitor (5-1) string is located on feeder line (3-1), metal mistake Hole (5-3) is arranged on the vicinity of feeder line (3-1), and interdigital capacitor (5-1) and metallic vias (5-3) are connected by trickle band wire (5-2) Connect.

7. a kind of ultra-compact Section of Microstrip Antenna Array according to claim 6, it is characterised in that：Different feeder line (3- 1) number of the composite left-and-right-hand phase-shifting unit on changes successively.

8. a kind of ultra-compact Section of Microstrip Antenna Array according to claim 1, it is characterised in that：Antenna array unit Feeder line (3-1) at least one T junction (4) is provided with and feed between.