WO2018166300A1 - Filtering antenna - Google Patents

Abstract

The present invention provides a filtering antenna, comprising a planar printed antenna module. The planar printed antenna module comprises: a first dielectric plate (4); a radiating element (1), the radiating element (1) being printed on the upper surface of the first dielectric plate (4); a second dielectric plate (5), the second dielectric plate (5) being disposed below the first dielectric plate; a floor (3), the floor (3) being printed on the lower surface of the second dielectric plate (5); and an antenna feeder, the antenna feeder being connected to the radiating element (1) and comprising a double-layer filtering component (2).

Description

Filter antenna Technical field

The invention belongs to the technical field of antennas, and relates to a filter antenna, in particular to a filter antenna which can be used for receiving and transmitting electromagnetic waves in a complex electromagnetic environment in the fields of radio frequency identification, radar and wireless communication.

Background technique

In recent years, wireless communication devices have gradually developed in the direction of light weight, low price, and high performance.

As the most important two passive components of the RF front-end circuit, the design of filters and antennas has always been the focus and hotspot of research. On the one hand, a good performance filter can filter out unwanted signals and is widely used in oscillation, amplification, frequency multiplication and mixing circuits. On the other hand, well-designed antennas can be used as sensors, transducers, radiators, and transducers. The transmitting antenna converts the electrical signal on the transmission line into electromagnetic waves and transmits them into free space; the receiving antenna receives the incident electromagnetic waves in the free space and then converts it into electrical signals to propagate on the transmission line. In the traditional design method, the filter and antenna are cascaded as two independent subsystems to the RF front-end circuit. Some systems also require the balun to perform single-ended signal and differential signal conversion. In order to eliminate the effects between the ports, they are usually connected by coaxial lines, waveguides or microstrip transmission lines. This cascading of discrete devices may cause filter and antenna port mismatch, which seriously affects the radiation efficiency and directivity of the antenna. At the same time, due to the existence of the matching circuit, the circuit becomes complicated, and the size and loss become large.

In recent years, techniques have been developed in which an antenna and a filter are designed as a whole device as a filter antenna. The filter antenna has radiation, impedance matching, filtering and balance conversion functions. However, the existing filter antenna or the out-of-band suppression band is too narrow, and the effect of wideband suppression is not achieved; or the size of the filter structure is large, and after the feed line is added to the antenna structure, the overall size of the antenna is made larger, and the miniaturization characteristic cannot be realized. .

Summary of the invention

According to an embodiment of the present invention, there is provided a filter antenna, the filter antenna comprising a planar printed antenna module, wherein the planar printed antenna module comprises: a first dielectric plate; a radiating unit, the radiating unit is printed on the An upper surface of the first dielectric plate; a second dielectric plate disposed under the first dielectric plate; a floor printed on a lower surface of the second dielectric plate; and an antenna a feeder, the antenna feed is coupled to the radiating element and includes a dual layer filter assembly.

In some embodiments, the dual layer filter assembly includes: a stepped impedance resonator printed on an upper surface of the first dielectric plate and electrically connected to the radiating element; and a via structure The via structure is disposed on the second dielectric plate and below the stepped impedance resonator.

In some embodiments, the antenna feed line further includes a first antenna feed line portion and a second antenna feed line portion, the first antenna feed line portion and the second antenna feed line portion being printed on the first dielectric plate a surface, and the first antenna feed portion is coupled to the radiating element, and the stepped impedance resonator is coupled between the first antenna feed portion and the second antenna feed portion.

In some embodiments, the stepped impedance resonator is a U-shaped stepped impedance resonator, the U-shaped stepped impedance resonator has a rectangular resistor; the U-shaped stepped impedance resonator further includes a U-shaped resistor, The U-shaped resistor has a pair of projecting arms, and each of the projecting arms is respectively connected to a rectangular resistor extending in the extending direction of the projecting arm.

In some embodiments, the width of the projecting arm is less than the width of the rectangular resistor and the outer edge of the projecting arm is flush with the outer edge of the corresponding rectangular resistor.

In some embodiments, the via structure includes: a metal patch printed on an upper surface of the second dielectric plate and located directly under the rectangular resistor of the stepped impedance resonator And a metal through hole, the metal through hole is formed on the second dielectric plate and located under the metal patch, wherein the metal patch is electrically connected to the floor through the metal through hole .

In some embodiments, the radiating element is a triangular radiating patch, a dome shaped radiation patch, and the radiating element is one of a circular radiating patch.

DRAWINGS

1 is a schematic structural view of a filter antenna according to Embodiment 1 of the present invention;

2 is a schematic structural view of a radiation unit according to Embodiment 1 of the present invention;

Figure 3 is a side view of the double layer filter assembly of the present invention;

Figure 4 is a partial perspective view of the double layer filter assembly of the present invention;

5 is a schematic diagram of a single layer filter structure without a via structure;

Figure 6 is a plan view of the double layer filter assembly of the present invention;

7 is a comparison diagram of S-parameter simulation of the double-layer filter component of the present invention and a general single-layer filter structure;

8 is a graph showing simulation results of return loss (S11) of an antenna according to Embodiment 1 of the present invention and a conventional microstrip fed antenna;

9 is a graph showing gain simulation results of an antenna according to Embodiment 1 of the present invention and an antenna of a conventional microstrip feed;

10 is a diagram showing a simulation result of a pattern of an antenna according to Embodiment 1 of the present invention and a conventional microstrip-fed antenna;

Figure 11 is a front elevational view of a filter antenna according to Embodiment 2 of the present invention;

Figure 12 is a schematic view of a radiation unit according to Embodiment 2 of the present invention;

13 is a S11 simulation result diagram of an antenna according to Embodiment 2 of the present invention and an ordinary microstrip-fed antenna;

14 is a graph showing gain simulation results of an antenna according to Embodiment 2 of the present invention and an antenna of a conventional microstrip feed;

15 is a diagram showing a simulation result of a pattern of an antenna according to Embodiment 2 of the present invention and an antenna of a conventional microstrip feed;

Figure 16 is a schematic diagram of a filter antenna according to Embodiment 3 of the present invention;

17 is a S11 simulation result diagram of an antenna according to Embodiment 3 of the present invention and an ordinary microstrip fed antenna;

18 is a graph showing gain simulation results of an antenna according to Embodiment 3 of the present invention and an antenna of a conventional microstrip feed;

Fig. 19 is a view showing a result of simulation of a pattern of an antenna according to Embodiment 3 of the present invention and an antenna of a conventional microstrip feed.

detailed description

The invention provides a miniaturized wide stopband filter antenna for solving the problem that the band suppression band of the existing miniaturized filter antenna is too narrow.

The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

FIG. 1 , FIG. 11 and FIG. 16 respectively illustrate three structural diagrams of a miniaturized wide stop band filter antenna provided by the present invention, and the filter antenna includes a planar printed antenna module. As can be seen from the figure, the planar printed antenna module of the present invention comprises: a first dielectric plate 4; a radiating unit 1 printed on the upper surface of the first dielectric plate 4; a second dielectric plate 5, the second dielectric plate 5 disposed below the first dielectric panel 4; a floor 3 printed on the lower surface of the second dielectric panel 5; and an antenna feed line connected to the radiating element 1 and including a double layer filter assembly 2. Wherein, the double-layer filter component 2 is used as a part of the antenna feed line for realizing broadband external suppression.

The invention uses a planar printed antenna to realize radiation, and uses a miniaturized wide stopband low-pass filter component to access the antenna feed line instead of the original feeder of the antenna, thereby realizing broadband external suppression without increasing the overall size of the antenna, so that the antenna is The performance in a complex electromagnetic environment is more stable.

The structure of the filter antenna of the present invention will be described in detail below with reference to the accompanying drawings and the three embodiments.

Example 1

1 is a schematic structural view of a filter antenna according to a first embodiment of the present invention. As can be seen from FIG. 1, the filter antenna of the present invention includes a first dielectric plate 4 and a second dielectric plate 5 disposed above and below. The upper surface of the first dielectric plate 4 is printed with a radiation unit 1 and an antenna feed line connected to the radiation unit 1. The antenna feed line includes a two-layer filter assembly 2 for achieving wideband rejection, which is a low pass filter assembly. The lower surface of the second dielectric plate 5 is printed with a floor 3.

Specifically, as shown in FIGS. 1, 3, and 4, the double layer filter assembly of the present invention includes a step impedance resonator 21 and a via structure 22. Among them, the step impedance resonator 21 is printed on the upper surface of the first dielectric plate 4 and is connected between the first antenna feed portion 231 and the second antenna feed portion 232 which are also printed on the upper surface of the first dielectric plate 4. The stepped impedance resonator 21 is electrically connected to the radiating element 1 through the first antenna feed line portion 231.

The stepped impedance resonator is a U-shaped stepped impedance resonator having a U-shaped resistor 212 and a pair of rectangular resistors connected to a pair of projecting arms of the U-shaped resistor and extending forward in the extending direction of the projecting arm 211. The width W2 of the projecting arm of the U-shaped resistor is smaller than the width W3 of the rectangular resistor 211. The outer edge of the projecting arm of the U-shaped resistor is flush with the outer edge of the corresponding rectangular resistor. The via structure 22 is disposed on the second dielectric plate 5 and under the at least one stepped impedance resonator 21 for reducing the cutoff frequency of the antenna and widening the stop band multiplication of the antenna.

Referring to FIG. 3 and FIG. 4 , the through hole structure 22 is located in the second dielectric plate 5 , and the through hole structure 22 includes: a metal patch 221 printed on the upper surface of the second dielectric plate 5 , The metal patch 221 is a rectangular metal patch directly under the rectangular resistor 211 of the stepped impedance resonator 21; and a metal through hole 222 is formed on the second dielectric plate 5 at the metal patch 221 Below the second dielectric plate 5 is penetrated in the thickness direction of the second dielectric plate 5. In practice, a through hole may be formed in the second dielectric plate 5, and a metal layer is plated on the inner wall of the through hole of the second dielectric plate 5 by a prior art process to conduct electricity. Thereby, the metal patch 221 is electrically connected to the floor panel 3 through the metal through hole 222. In the present embodiment, the size of the rectangular metal patch 221 is the same as that of the rectangular resistor 211.

In this embodiment, the thickness of the first dielectric plate 4 is H1=0.2 mm, and the thickness of the second dielectric plate 5 is H2=0.5 mm. Both dielectric plates are made of FR-4 (flame resistant material grade) material, and the two dielectric plates are the same size. , both are 75mm × 42mm.

The shape and size of the radiating element 1 are determined by the operating frequency band of the filter antenna. In the present embodiment, the radiating element 1 employs a triangular radiating patch. Referring to FIG. 2, a sharp corner of the triangular radiation patch for connecting (through the first antenna feed portion 231) to the U-shaped stepped impedance resonator 21 is processed into a rectangular shape, wherein the geometry of the triangular radiation patch is as follows: Side M = 35 mm, height N = 28 mm, rectangular width W4 = 0.5 mm, rectangular length G = 0.5 mm.

In order to explain the action of the via structure 22, Fig. 5 of the present invention shows a schematic diagram of a filter structure without a via structure as a comparative example. Compared with the double-layer filter assembly disclosed in the embodiments of the present invention, the filter structure of FIG. 5 is a single-layer dielectric substrate structure. The size of the U-shaped step impedance resonator of the filter structure is the same as that of Embodiment 1, and the thickness of the dielectric substrate is H = H1 + H2.

Referring to FIG. 6, the size of each segment of the U-shaped step impedance resonator 21 and related components according to Embodiment 1 of the present invention may be respectively the following values: the width of the projecting arm W2 = 0.2 mm, and the U-shaped step impedance resonator 21 The width L2=2.2mm, the width of the rectangular resistor W3=1mm, the distance from the two ends of the U-shaped step impedance resonator to the first and second antenna feeder portions L4=5mm, L3=5mm, metal pass The radius of the hole 222 is R = 0.25 mm. The length of the first antenna feed portion 231 connected to the radiation unit 1 is L1 = 3 mm, the length of the second antenna feed portion 232 is L1' = 3 mm, and the width of the first antenna feed portion 231 and the second antenna feed portion 232 is W1 = 0.6 mm. . The width of the floor panel 3 is L1 + L1' + L2, and the length of the floor panel 3 is flush with the boundary of the second dielectric panel. With respect to the cutoff frequency of 2.35 GHz, the size of the filter component of this embodiment is only 0.08 λ × 0.06 λ × 0.005 λ, where λ is the wavelength corresponding to the cutoff frequency.

The simulation components in the first embodiment and the comparative example were simulated using the commercial simulation software HFSS_13.0, and the results are shown in FIG.

The S-parameters, gain and 1.9 GHz pattern of the antenna of Example 1 and the antenna of the ordinary microstrip feed (original antenna) were simulated by the commercial simulation software HFSS_13.0. The results of the simulation calculation are shown in Fig. 8 and Fig. 9 and Figure 10 shows.

7 is a comparison of simulation results of S parameters of the double-layer filter assembly 2 and the S-parameters of the single-layer filter structure without the via structure shown in FIG. 5 according to Embodiment 1 of the present invention. When the H2 in the embodiment 1 is changed, the total thickness H1+H2 of the filter structure is unchanged. It can be seen from the figure that when H2 is lowered, the cutoff frequency of the double-layer filter component gradually approaches the cutoff frequency of the single-layer filter structure without the via structure, and when H2 is increased, the cutoff frequency of the double-layer filter component is continuously reduced. When H2 is increased from 0.2mm to 0.6mm, the cutoff frequency of the double-layer filter component is reduced from 2.85GHz to 1.76GHz, while the maximum frequency of the reverse transmission coefficient (S12) less than -10dB is slightly reduced from 12.4GHz to 11.8GHz, filtering The maximum frequency of the stop band of the structure is increased from 4.35 to 6.7 with respect to the cutoff frequency.

The above simulation results show that the double-layer filter component with through-hole structure has more significant miniaturization and wide stopband characteristics. Since the via structure 22 is located below the U-shaped stepped impedance resonator 21, it reduces the cutoff frequency of the filter structure without increasing the circuit size, and broadens the stop band multiplication of the filter structure, thereby achieving better performance. Miniaturization features.

Referring to Fig. 8, the antenna of Embodiment 1 achieves a good out-of-band suppression effect within 13.1 GHz as compared with a conventional microstrip-fed antenna.

Referring to Fig. 9, the antenna of the first embodiment has a good suppression effect on the out-of-band gain as compared with the conventional microstrip-fed antenna. The gain of the center frequency of 1.9 GHz is reduced by 0.2 dB due to the insertion loss of the filter structure.

Referring to Fig. 10, the first embodiment has a good pattern at a center frequency of 1.9 GHz, indicating that the filter antenna of the present embodiment performs well in the operating band.

Example 2

Figure 11 is a block diagram showing the structure of a filter antenna according to Embodiment 2 of the present invention. As can be seen from Fig. 11, the radiation unit 1 of the present embodiment employs a dome-shaped radiation patch. In the present embodiment, the thickness of the first dielectric plate 4 is H1=0.2 mm, and the thickness of the second dielectric plate 5 is H2=0.5 mm. Both dielectric plates are made of FR-4 material, and the dimensions are both 42 mm×29 mm. Wherein, the size of each segment of the U-shaped stepped impedance resonator 21 and related components (refer to FIG. 6) can respectively adopt the following values: W1=1.5mm, L1=3mm, W2=0.2mm, L2=2mm, L4=5mm, W3 = 0.9 mm, L3 = 5 mm, radius of the metal through hole R = 0.25 mm.

Referring to Fig. 12, the size of the radiating element in Embodiment 2 is: width W5 = 0.5 mm, length of long longitudinal side L5 = 15 mm, length of lateral side L6 = 12 mm, length of short longitudinal side L7 = 3.8 mm.

The S-parameters, gains, and 2.3 GHz patterns of the antenna of the above-described Embodiment 2 were simulated using the commercial simulation software HFSS_13.0, and the results are shown in FIGS. 13, 14, and 15.

Referring to Fig. 13, the antenna of Embodiment 2 achieves a good out-of-band suppression effect within 14.4 GHz as compared with a conventional microstrip-fed antenna.

Referring to Fig. 14, the antenna of the second embodiment has a good suppression effect on the out-of-band gain as compared with the conventional microstrip-fed antenna. The gain of the center frequency of 2.3 GHz is reduced by 0.4 dB due to the insertion loss of the filter structure.

Referring to Fig. 15, the second embodiment has a good pattern at a center frequency of 2.3 GHz, indicating that the present invention performs well in the operating band.

Example 3

Figure 16 is a block diagram showing the structure of a filter antenna according to Embodiment 3 of the present invention. As can be seen from Fig. 16, the radiating element 1 of the present embodiment employs a circular radiating element, and the circular radiating element is provided with a rectangular radiating patch on the side connected to the U-shaped stepped impedance resonator. In this embodiment, the thickness of the first dielectric plate 4 is H1=0.2 mm, and the thickness of the second dielectric plate 5 is H2=0.6 mm. Both dielectric plates are made of FR-4 material, and the dimensions are both 85 mm×47 mm. Wherein, the size of each segment of the U-shaped step impedance resonator 21 can be respectively adopted as follows: W1=0.6mm, L1=3mm, W2=0.2mm, L2=2.2mm, L4=5mm, W3=1mm, L3=5mm, The radius of the metal through hole is R = 0.25 mm. The dimensions of the radiating element are as follows: the radius of the circle R1 = 17 mm, the length of the rectangular radiating patch G = 0.5 mm, and the width of the rectangular radiating patch W4 = 0.6 mm.

The S parameters, the gain, and the 2.3 GHz pattern of the antenna of the above-described Embodiment 3 were simulated by the commercial simulation software HFSS_13.0, and the results are shown in Figs. 17, 18, and 19.

Referring to Fig. 17, the antenna of Embodiment 3 achieves a good out-of-band suppression effect at 12.9 GHz as compared with a conventional microstrip-fed antenna.

Referring to Fig. 18, the antenna of the third embodiment has a good suppression effect on the out-of-band gain as compared with the conventional microstrip-fed antenna. The gain of the center frequency of 1.9 GHz is reduced by 0.3 dB due to the insertion loss of the filter structure.

Referring to Fig. 19, the third embodiment has a good pattern at a center frequency of 1.9 GHz, indicating that the present invention performs well in the operating band.

The simulation results of the above three embodiments show that the antenna is improved to a filter antenna under the premise that the overall size of the antenna remains unchanged, and the filter antenna has good working performance in the band, and achieves miniaturization and wideband suppression. effect.

It should be noted that the radiation unit of the present invention may employ other types of radiation units in addition to the radiation units of the above three shapes.

Further, the stepped-impedance resonator of the present invention may be directly connected to the radiation unit, and the step-impedance resonator may adopt other shapes than the shapes shown in FIGS. 4 to 6.

In summary, the filter antenna of the present invention has the following advantages compared with the prior art:

1. The filter antenna of the present invention replaces a part of the feeder of the original antenna by using a miniaturized double-layer filter component, thereby realizing the filtering function without increasing the overall size of the antenna.

2. The double-layer filter assembly of the present invention has the characteristics of a wide stop band, thereby achieving a good out-of-band suppression effect.

3. The filter antenna of the present invention has a through-hole structure located below the U-shaped stepped impedance resonator, thereby reducing the cutoff frequency of the filter component without increasing the circuit size, and widening the stop band multiplication of the filter component, thereby Achieve better miniaturization features.

The above is a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements, retouchings, and feature combinations without departing from the principles of the present invention. Combinations of features and features are also considered to fall within the scope of the invention.

Claims (13)

1. A filter antenna includes a planar printed antenna module, wherein the planar printed antenna module comprises:

   First dielectric plate (4);

   a radiation unit (1), the radiation unit (1) being printed on an upper surface of the first dielectric plate (4);

   a second dielectric plate (5), the second dielectric plate (5) being disposed below the first dielectric plate (4);

   a floor (3) printed on a lower surface of the second dielectric panel (5);

   An antenna feed line connected to the radiating element (1) and comprising a double layer filter assembly (2).
2. The filter antenna of claim 1 wherein said dual layer filter component (2) comprises:

   a stepped impedance resonator (21) printed on an upper surface of the first dielectric plate (4) and electrically connected to the radiating element (1);

   A via structure (22) is disposed on the second dielectric plate (4) and below the stepped impedance resonator (21).
3. The filter antenna according to claim 2, wherein

   The antenna feed line further includes a first antenna feed portion (231) and a second antenna feed portion (232), the first antenna feed portion (231) and the second antenna feed portion (232) printed on the An upper surface of the first dielectric plate (4), and the first antenna feed portion (231) is connected to the radiation unit (1), and

   The stepped impedance resonator (21) is connected between the first antenna feed line portion (231) and the second antenna feed line portion (232).
4. The filter antenna according to claim 2, wherein

   The stepped impedance resonator (21) is a U-shaped stepped impedance resonator having a rectangular resistor (211).
5. The filter antenna according to claim 4, wherein

   The U-shaped stepped impedance resonator further includes a U-shaped resistor (212) having a pair of projecting arms, and each of the projecting arms is coupled to a respective one of the projecting arms A rectangular resistor (211) extending in the extending direction.
6. The filter antenna according to claim 5, wherein

   The width (W2) of the projecting arm is smaller than the width (W3) of the rectangular resistor (211), and the outer edge of the projecting arm is flush with the outer edge of the corresponding rectangular resistor.
7. The filter antenna according to any one of claims 4 to 6, wherein the via structure (22) comprises:

   a metal patch (221) printed on an upper surface of the second dielectric plate (4) and located in a rectangular resistor (211) of the stepped impedance resonator (21) Directly below;

   a metal through hole (222), the metal through hole (222) is formed on the second dielectric plate (4), and is located below the metal patch (221).

   The metal patch (221) is electrically connected to the floor (3) through the metal through hole (222).
8. The filter antenna of claim 7, wherein the metal patch (221) is a rectangular metal patch.
9. The filter antenna of claim 8, wherein the rectangular metal patch has the same size as the rectangular resistor (211).
10. A filter antenna according to claim 1, wherein the shape and size of said radiating element (1) are determined in accordance with an operating band of said filtering antenna.
11. A filter antenna according to claim 1 or 10, wherein said radiating element is a triangular radiating patch.
12. A filter antenna according to claim 1 or 10, wherein said radiating element is a dome shaped radiation patch.
13. A filter antenna according to claim 1 or 10, wherein said radiating element is a circular radiating patch

Images