CN109193147B - A Low Profile Filter Antenna Using Slotted Dielectric Patch - Google Patents

Abstract

The invention relates to a low-profile filter antenna adopting a grooved dielectric patch, which comprises a metal reflection floor, a substrate and the dielectric patch which are sequentially stacked from bottom to top, wherein a feeder line connected with the dielectric patch is arranged on the upper surface of the substrate and used for direct feeding, a pair of inner wall printed metal grooves are arranged at the connection part of the feeder line and are symmetrical to the connection part of the feeder line at one side of the dielectric patch connected with the feeder line, and the dielectric constant of the dielectric patch is 90. The dielectric patch filter antenna has the advantages of simple structure, easy manufacture, small volume, low profile and the like. Through the silver-coated groove, the miniaturization of the antenna can be realized, a radiation zero point can be introduced into a lower frequency band, and the antenna can obtain good filtering characteristics by combining the radiation zero point brought by a high-order mode of the dielectric patch.

Description

A Low Profile Filter Antenna Using Slotted Dielectric Patch

technical field

The present invention relates to the technical field of wireless communication, in particular to a low-profile dielectric patch filter antenna.

Background technique

In wireless communication systems, antennas and filters are usually designed as two separate components. In this case, their respective matching circuits and additional transmission lines for connecting them are required, which inevitably increases the system size and introduces additional losses and loading effects. To overcome this, co-design methods of various filters and antennas (also called filter antennas) have been widely developed in recent years. Design methods can be mainly divided into three categories. One approach is to design bandpass/bandstop filters and antennas and then combine them. The second method is a variation of the first method, where the antenna acts as both a radiator and a final stage resonator of the filter. However, they all belong to cascade design, which makes the antenna structure complex and bulky, especially in the feeding network. To solve the cascade design problem, some scholars have proposed a third method: embedding some filtering structures into the antenna radiator to achieve a gain bandpass response, which means that the antenna radiator itself has filtering capability. Therefore, this method is an effective method to reduce the filter antenna size and loss. Additionally, radiators with filtering properties are attractive in dual-band arrays to reduce mutual coupling between elements operating at different frequencies.

As we all know, the dielectric resonator antenna, as a typical antenna, has the advantages of small size, light weight, and easy excitation. In recent years, dielectric resonator filter antennas have become a hot spot for high-frequency applications. However, the dielectric resonator filter antenna designed based on the above-mentioned first and second methods has a high profile and a bulky feeding structure. In order to reduce the profile of the dielectric resonator antenna, some scholars proposed a high-density dielectric patch antenna in 2013. Its main mode (the lowest-order resonance mode) is the TE ₁₁ mode and has a similar electric field distribution of the microstrip patch. .

After searching, it is found that the Chinese invention patent application CN 105720364 A discloses a dual-polarization filter antenna with high selectivity and low cross-polarization, no additional filter circuit is required, and the antenna itself integrates filter characteristics and radiation characteristics, which solves the problem of traditional level. The insertion loss and extra size of the filter antenna caused by the connected type. However, the disadvantage is that its structure is complicated, and the filtering characteristic is realized on the feeding network, rather than the filtering ability of the antenna radiator itself.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned defects of the prior art, and to propose a low-profile filter antenna with a simple structure using a slotted dielectric patch. The antenna feeds the dielectric patch by means of direct feeding. With the help of the non-radiating high-order mode of the dielectric patch and a pair of grooves with metal printed on the inner wall in the dielectric patch, two radiation nulls at the high and low ends can be obtained without adding any additional filter circuit, making the antenna The radiator itself has filtering capabilities. At the same time, the electrical length of the antenna is changed in the process of slotting the dielectric patch, thereby realizing the miniaturization of the antenna.

In order to achieve the above purpose, the low-profile filter antenna using a slotted dielectric patch proposed by the present invention includes a metal reflective floor, a substrate and a dielectric patch that are sequentially stacked from bottom to top, and the upper surface of the substrate is provided with a dielectric patch. The feeder connected to the sheet is used for direct power feeding. The side of the dielectric patch connected to the feeder is symmetrically provided with a pair of metal grooves printed on the inner wall at the connection of the feeder. The dielectric constant of the dielectric patch is greater than 40.

The dielectric patch filter antenna of the invention has the advantages of simple structure, easy manufacture, small volume and low profile. Through the introduction of the silver coating groove, not only the miniaturization of the antenna can be realized, but also the radiation null point can be introduced in the lower frequency band. Combined with the high frequency band radiation null point generated by the high-order mode of the dielectric patch, the antenna can obtain good filtering performance. . By changing the length and width of the slot, the operating frequency of the antenna and the position of the radiation null point will change regularly at the same time, so that it is easy to tune to the desired frequency for suppression.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings.

FIG. 1 is a perspective view of the slotted dielectric patch filter antenna of the present invention.

FIG. 2 is an exploded view of the slotted dielectric patch filter antenna of the present invention.

3 is a top view of the slotted dielectric patch filter antenna of the present invention.

FIG. 4 is a graph showing the simulated reflection coefficient (S ₁₁ ) and gain of the slotless dielectric patch antenna.

FIG. 5 is a graph showing the simulated reflection coefficient (S ₁₁ ) and gain of the slotted dielectric patch filter antenna of the present invention.

6 is a comparison diagram of the reflection coefficient (S ₁₁ ) and the gain curve of the simulation and test of the slotted dielectric patch filter antenna of the present invention.

FIG. 7 is the antenna radiation E-plane pattern of the simulation and test at the frequency point of 4.17 GHz for the slotted dielectric patch filter antenna of the present invention.

FIG. 8 is the antenna radiation H-plane pattern of the simulation and test at the frequency point of 4.17 GHz for the slotted dielectric patch filter antenna of the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

As shown in Figures 1-3, this embodiment adopts a low-profile filter antenna with a slotted dielectric patch, including a metal reflection floor 1, a substrate 2, and a dielectric patch 3 that are stacked in sequence from bottom to top. There is a feeder 4 connected to the dielectric patch for direct feeding. In this example, the substrate 2 is a printed circuit board, the metal reflective floor 1 is printed on the bottom surface of the printed circuit board 2 , and the feeder 4 is printed on the top surface of the printed circuit board 2 . A rectangular metal feeder 5 is printed on the middle of one side of the dielectric patch, and the feeder 4 is connected to the metal feeder 5. The side of the dielectric patch 3 connected to the feeder 4 is symmetrically provided with a pair of metal feeders 5. The inner wall is printed with a rectangular groove 6 of metallic silver, and the dielectric patch 3 is a microwave dielectric ceramic, and its dielectric constant ε _r = 90. In the filter antenna of this structure, the dielectric constant of the dielectric patch needs to be greater than 40.

The parameters of the antenna in this embodiment are shown in the following table

parameter <i>W</i>₁ <i>W</i>₂ <i>L</i>₁ <i>L</i>₂ <i>h</i>₁ Value (mm) 20 44 17 47 1.1 parameter <i>h</i>₂ <i>l</i> <i>w</i> <i>d</i> <i>t</i> Value (mm) 0.813 7 0.95 9.8 0.8

W1 is the width _of the dielectric patch, W2 is the width of the substrate, L1 is the length _of the dielectric patch, L2 is the length of the substrate, _h1 is the height _of the dielectric _patch , h2 is the height of the substrate , l _is the slot length, w is the width of the slot, d is the distance between the two slots, and t is the height of the metal feeder. By changing the length l and width w of the slot, the operating frequency of the antenna and the position of the radiation null point can be adjusted. The input matching of the antenna can be adjusted by changing the height t of the metal feeder.

Dielectric patches are made of high-density ceramic materials to replace microstrip metal patches. The dominant mode (lowest-order resonant mode) of the dielectric patch is the TM ₁₁ mode, and its electric field distribution is similar to that of the microstrip patch. Figure 4 shows the simulated reflection coefficient (S ₁₁ ) and gain of a slotless dielectric patch antenna fed directly by a microstrip line. Since the upper surface of the dielectric patch can be approximated as a magnetic wall, the radiation of the TM ₁₁ mode is along the two sides of the y-axis direction, and the polarization direction is along the x-axis. The electric field distribution of the higher-order mode HEM ₂₁ at the lowest end of the dielectric patch is perpendicular to the feeding microstrip line, so it is not excited (S ₁₁ ≈0 dB). More importantly, the HEM ₂₁ mode has no radiating elements in the x-axis polarization direction. Therefore, an inherent high-end radiation zero can be obtained under this excitation mode. At the same time, the higher-order mode HEM ₁₂ , whose electric field distribution is parallel to the feeder, can be excited and works well.

To create another radiation null at low frequencies for enhanced selectivity, this example etched a pair of slots along the x-axis in the dielectric patch and printed silver on three inner surfaces. Figure 5 shows the simulated _S11 and gain. As can be seen in Figures 4 and 5, the silvered grooves pull down the frequencies of the TM ₁₁ and HEM ₂₁ modes. At the same time, the inverse electric field is perpendicular to the slot, so the silver slot can generate another radiation null at low frequency. As the length l of the slot increases, the operating frequency of the antenna decreases, and the low-end and high-end radiation nulls are adaptive, with stable high selectivity. At the same time, the width w of the slot mainly affects the low-end radiation zero point, and has little effect on the high-end radiation zero point. Therefore, the two zeros can be independently controlled so that they can be easily tuned to the desired frequency for rejection.

The dielectric patch filter antenna of this embodiment is tested, and the test results are consistent with the simulation, as shown in FIG. 6 . The antenna has a narrow filter band, _S11 < -20 dB at center frequency f0 ₌ 4.17 GHz, two radiation nulls at 4.02 and 4.31 GHz are observed in the measured gain response, the passband edge is steep, and Has high selectivity. The maximum gain measured at 4.17 GHz is 4.8 dB. The E and H plane radiation patterns at 4.17 GHz are shown in Figures 7 and 8. The measured cross polarization is at least 15 dB lower than the main polarization. As can be seen from the figure, slight differences between the simulated and measured results can be observed, which can be attributed to manufacturing and measurement errors.

In addition to the above-described embodiments, the present invention may also have other embodiments. All technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (6)

1. A low-profile filter antenna using a slotted dielectric patch, comprising a metal reflection floor, a substrate and a dielectric patch that are stacked sequentially from bottom to top, and the upper surface of the substrate is provided with a feeder that is connected to the dielectric patch, For direct power feeding, the side of the dielectric patch connected to the feeder is symmetrically provided with a pair of inner wall printed metal grooves at the connection of the feeder, and the dielectric constant of the dielectric patch is greater than 40; the substrate is a printed circuit board, the metal reflection floor is printed on the bottom surface of the printed circuit board, and the feeder is printed on the top surface of the printed circuit board; a metal feeder is arranged in the middle of one side of the dielectric patch, and the feeder is connected to the metal feeder. Electrical connection. 2 . The low-profile filter antenna using a slotted dielectric patch according to claim 1 , wherein the metal feeder is printed and arranged on the side surface of the dielectric patch. 3 . 3. The low-profile filter antenna using a slotted dielectric patch according to claim 1, wherein the metal feeder is rectangular, and the bottom edge is flush with the bottom surface of the dielectric patch, and the metal feeder is in the shape of a rectangle. The height t of the sheet does not exceed the height of the media patch. 4 . The low-profile filter antenna using a slotted dielectric patch according to claim 3 , wherein the slot is a rectangular slot, and the metal coated on the inner wall of the slot is silver, manganese, copper, tin or nickel. 5 . 5. The low-profile filter antenna using a slotted dielectric patch according to claim 4, wherein the dielectric patch is located at the center of the substrate, the width of the substrate is W2=44mm, and the length of the substrate L2= 47mm, the height of the substrate h2=0.813mm, the length of the medium patch L1=17mm, the width of the medium sticker W1=20mm, the height of the medium patch h1=1.1mm, the slot width w=0.95mm , the slot length l=7mm, the distance between the two slots d=9.8mm. 6 . The low-profile filter antenna using a slotted dielectric patch according to claim 5 , wherein the dielectric constant of the dielectric patch is 90. 7 .

Images