Single, dual-band reconfigurable microstrip quasi-yagi antenna

Abstract

This invention discloses a single- and dual-band reconfigurable microstrip quasi-Yagi antenna. The antenna includes a dielectric substrate, a coplanar radiating patch, a first director, a second director, a microstrip feed line, and four radio frequency (RF) PIN diodes. The coplanar radiating patch is printed on the front side of the dielectric substrate. RF PIN diodes are respectively disposed between the first and second directors, the main radiating patch of the coplanar radiating patch, and the four parasitic radiating patches. The microstrip feed line is printed on the back side of the dielectric substrate. By reasonably setting the conduction and cutoff of the four PIN diodes, this invention can operate in the n78 or n79 frequency band, or simultaneously operate in both the n78 and n79 frequency bands as a dual-band antenna. This antenna achieves good directional radiation in all operating frequency bands, with stable radiation performance. It is a novel, small-sized, lightweight, low-profile, and small-scattering-cross-section directional antenna.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, and in particular relates to a single- or dual-band reconfigurable microstrip quasi-Yagi antenna. Background Technology

[0002] With the technological transformation and rapid promotion of 5G communication, 5G communication is gradually becoming the mainstream communication technology. As leading enterprises in China's commercial communications industry, the four major operators, China Mobile, China Telecom, China Unicom, and China Broadcasting Network, are keeping up with the technological trend and actively carrying out 5G deployment. They have already completed 5G coverage in key areas of many cities. In the 5G spectrum allocation of the four major operators in China, the mature n78 (3.3-3.8GHz) and n79 (4.4-5.0GHz) are both key 5G frequency bands for deployment (among which, China Mobile owns the 4.8-4.9GHz band, China Telecom owns the 3.4-3.5GHz band, China Unicom owns the 3.5-3.6GHz band, China Broadcasting Network owns the 4.9-5.0GHz band, and China Unicom, China Telecom, and China Broadcasting Network share the 3.3-3.4GHz band).

[0003] As an indispensable key component in 5G communication, the performance of antennas largely determines the quality of the communication system. For communication applications using multiple frequency bands such as n78 and n79, a single antenna is insufficient for the use of multi-functional communication devices. However, adopting a multi-antenna design would inevitably increase the weight burden and manufacturing costs of the communication equipment, wasting space resources. Furthermore, improper consideration of electromagnetic compatibility issues between antennas could significantly reduce communication quality. To avoid these drawbacks, achieving tunable multiplexing of resonant frequencies on a single antenna has become a current research focus. The microstrip quasi-Yagi antenna, as a classic directional antenna, combines the advantages of microstrip and Yagi antennas, possessing high gain, good directional radiation characteristics, light weight, low profile, and small scattering cross section. It has been widely used in satellite communication, spectrum environment monitoring, weapon fuses, and other fields. Combining frequency reconfigurable technology with microstrip quasi-Yagi antenna technology allows for real-time reconfiguration of the antenna's resonant frequency in a 5G communication environment based on actual needs, while simultaneously satisfying high-gain directional characteristics. However, there are currently very few frequency reconfigurable microstrip quasi-Yagi antennas that combine both technologies and are applied to the 5G band. In existing research, such as the paper "A Frequency Reconfigurable End-Fire Antenna Applied to 5G-FR1" published by Shang Feng et al., a reconfigurable end-fire antenna with a center resonant frequency of 3.5GHz or 4.9GHz was proposed. This design utilizes a total of 10 switches to achieve frequency switching. The frequency switching function is complex to implement, has few frequency modulation modes, and requires multiple switch control circuits, making it difficult to manufacture. In the patent application with publication number CN107785671A entitled "A frequency-reconfigurable microstrip patch Yagi antenna and reconfiguration method", a frequency-reconfigurable microstrip patch antenna with a center tuning frequency that can be adjusted from 14.2GHz to 13.15GHz is proposed. This antenna adopts a three-layer structure and uses liquid crystal material to achieve frequency reconfiguration. The cost is high and the complex frequency modulation method is affected by many parameters. The antenna radiation gain is low and frequency reconfiguration is difficult in practical applications. Summary of the Invention

[0004] In view of this, the present invention provides a single / dual-band reconfigurable microstrip quasi-Yagi antenna for use in the n78 and n79 frequency bands of 5G communication. The present invention combines frequency reconfiguration technology with microstrip quasi-Yagi antenna technology, enabling the antenna to switch frequencies between the n78 and n79 frequency bands. At the same time, it has good electrical performance and stable directional radiation performance. The invention has low production cost, low profile, small scattering cross-section, simple structure, easy manufacturing, and low processing difficulty, which is conducive to engineering implementation.

[0005] To achieve the above objectives, the technical solution created by this invention is implemented as follows:

[0006] A single- or dual-band reconfigurable microstrip quasi-Yagi antenna is characterized by comprising a dielectric substrate, wherein a coplanar radiating patch, a first director, and a second director are printed on the front side of the dielectric substrate, the bottom of the coplanar radiating patch is connected to the lower edge of the front side of the dielectric substrate, a first radio frequency PIN diode, a second radio frequency PIN diode, a third radio frequency PIN diode, and a fourth radio frequency PIN diode are disposed on the coplanar radiating patch, and a microstrip feed line is printed on the back side of the dielectric substrate, the bottom end of the microstrip feed line being connected to the lower edge of the back side of the dielectric substrate.

[0007] Specifically, the main radiating patch consists of a coplanar stripline, two pairs of unequal-length rectangular double dipoles, and a truncated ground plane with loaded rectangular stubs. Based on the fundamental principle of microstrip quasi-Yagi antennas, the coplanar stripline serves as the excitation source for the main radiating patch, transmitting electromagnetic energy to the double dipoles. The double dipoles, acting as the excitation elements of the quasi-Yagi antenna, determine the antenna's resonant frequency. The design of the two pairs of unequal-length rectangular double dipoles in this invention enables the antenna to operate in both the n78 and n79 frequency bands of 5G communication. The truncated ground plane with loaded rectangular stubs acts as a reflector for the quasi-Yagi antenna, suppressing back lobe radiation and improving the front-to-back ratio of the radiation pattern. This invention effectively reduces the antenna's lateral dimension while functioning as a reflector by symmetrically loading two extended rectangular stubs onto both ends of the truncated ground plane.

[0008] Furthermore, the coplanar stripline has three stepped slots that increase in width from bottom to top along the centerline of the dielectric substrate. This structure is equivalent to a balun structure, achieving the purpose of transitioning the coplanar stripline from the three stepped slots to the double dipole impedance.

[0009] Furthermore, the first and second directors, serving as the guiding elements of the quasi-Yagi antenna, can effectively concentrate electromagnetic energy in the antenna's end-firing direction, improving the antenna's radiation efficiency in the operating frequency band and enhancing the directivity of the main lobe radiation direction.

[0010] Furthermore, the microstrip feed line possesses the characteristics of a broadband impedance transformer, achieving good impedance matching with a 50Ω feed source. This invention employs a microstrip line with a coplanar stripline transition band as the feed method. By providing a 180° phase delay, the unbalanced input signal can be converted into a balanced signal capable of propagating on a dual dipole, thus realizing the directional radiation characteristics of the Yagi antenna. Moreover, the microstrip feed line structure designed in this invention can also overcome the narrow bandwidth limitation of traditional microstrip quasi-Yagi antennas, effectively widening the antenna's impedance bandwidth.

[0011] Furthermore, the parasitic radiating patch is loaded mainly close to the two pairs of unequal-length rectangular double dipoles of the main radiating patch. This does not change the basic structure of the microstrip quasi-Yagi antenna, nor does it affect the directional radiation characteristics of the antenna itself, thus achieving frequency reconstruction while realizing high-gain radiation.

[0012] Furthermore, the coplanar radiating patch on the front side of the dielectric substrate is composed of a main radiating patch and a parasitic radiating patch. An RF PIN diode is disposed in the gap between the two. The conduction or cutoff of the RF PIN diode extends or cuts off the distribution path of the current on the antenna surface, changes the field distribution, and affects the antenna resonant frequency, thereby realizing frequency reconstruction.

[0013] Compared with existing technologies, the single- and dual-band reconfigurable microstrip quasi-Yagi antenna described in this invention has the following advantages:

[0014] The antenna provided by this invention can flexibly switch between the n78 and n79 frequency bands, making it suitable for new 5G communication frequency bands. The frequency switching method is simple and effective and has three frequency switching modes. By reasonably setting the conduction and cutoff of four PIN diodes, this invention can work in the n78 or n79 frequency bands, or it can work as a dual-band antenna in both the n78 and n79 frequency bands simultaneously.

[0015] This invention creates an antenna that achieves good impedance bandwidth and impedance matching in the n78 and n79 frequency bands of 5G communication by designing unequal-length double dipoles, designing a coplanar stripline along the center line of the dielectric substrate with a three-step slot that is narrower and wider from bottom to top, and designing an improved microstrip line transition band coplanar stripline feeding method.

[0016] This invention creates an antenna with a single-layer structure, which is small in size, lightweight, has a low profile, and a small scattering cross-section. It can be installed on various communication equipment platforms, facilitating modular design of communication equipment and minimizing structural interference with other communication modules, thus possessing high engineering application value.

[0017] This invention presents an antenna with a clear working principle, a novel and simple structure, and can be manufactured using conventional production methods, enabling low-cost and high-efficiency production. The antenna has a wide operating bandwidth, stable electrical performance, requires minimal physical testing and adjustment, and is easy to implement in engineering.

[0018] The antenna provided by this invention achieves good directional radiation in all operating frequency bands, with stable radiation performance. It can be used in various devices such as spectrum monitoring, signal blind spot filling, and communication relay. It is suitable for various 5G communication scenarios, both indoors and outdoors, and also provides a new array element idea for 5G communication antenna array design. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0020] Figure 1 This is a front structural view of one embodiment of the antenna created by the present invention;

[0021] Figure 2 This is a rear structural diagram of one embodiment of the antenna invented in this invention;

[0022] Figure 3 This is a return loss curve of the antenna in Embodiment 1 of the present invention;

[0023] Figure 4 This is the far-field radiation pattern at 3.6 GHz when the antenna operates in the n78 frequency band in Embodiment 1 of the present invention;

[0024] Figure 5 This is the far-field radiation pattern at 4.8 GHz when the antenna operates in the n79 frequency band in Embodiment 1 of the present invention;

[0025] Figure 6 This is the far-field radiation pattern of the antenna in Embodiment 1 of the invention when it operates in dual-frequency modes n78 and n79.

[0026] Explanation of reference numerals in the attached figures

[0027] 1-Dielectric substrate; 2-Coplanar radiating patch; 3-First director; 4-Second director; 5-Microstrip feeder. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0029] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] This invention creates and designs a single / dual-band reconfigurable microstrip quasi-Yagi antenna (hereinafter referred to as the antenna, see n78 and n79 bands) for use in 5G communication. Figure 1-2 The antenna includes a dielectric substrate 1, a coplanar radiating patch 2, a first director 3, a second director 4, a microstrip feed line 5, a first RF PIN diode (SW1), a second RF PIN diode (SW2), a third RF PIN diode (SW3), and a fourth RF PIN diode (SW4). The coplanar radiating patch 2, the first director 3, and the second director 4 are printed on the front side of the dielectric substrate. The bottom of the coplanar radiating patch 2 is connected to the lower edge of the front side of the dielectric substrate 1. The first RF PIN diode (SW1), the second RF PIN diode (SW2), the third RF PIN diode (SW3), and the fourth RF PIN diode (SW4) are disposed on the coplanar radiating patch 2. By controlling the conduction or cutoff of the RF PIN diodes, the antenna operating frequency can be reconstructed. The microstrip feed line 5 is printed on the back side of the dielectric substrate, and the bottom end of the microstrip feed line 5 is connected to the lower edge of the back side of the dielectric substrate 1.

[0033] The coplanar radiating patch 2 of the antenna includes a main radiating patch and parasitic radiating patches. The main radiating patch consists of a coplanar stripline, two pairs of unequal-length rectangular double dipoles, and a truncated ground plane with loaded rectangular branches. The coplanar stripline has stepped slots that increase in width from bottom to top along the centerline of the dielectric substrate. The parasitic radiating patches are divided into an upper parasitic radiating patch and a lower pair of parasitic radiating patches. The upper parasitic radiating patch consists of two rounded rectangles of the same shape and size, and is connected to the left and right sides of the coplanar stripline of the main radiating patch by a first RF PIN diode (SW1) and a second RF PIN diode (SW2). The lower parasitic radiating patch consists of two rectangles of the same shape and size, and is connected to the left and right sides of the lower rectangular double dipole of the main radiating patch by a third RF PIN diode (SW3) and a fourth RF PIN diode (SW4). The main radiating patch and the two pairs of parasitic radiating patches are symmetrically placed on the left and right sides of the front side of the dielectric substrate 1, with respect to the centerline of the dielectric substrate 1.

[0034] The first director 3 and the second director 4 of the antenna are rectangular patches of the same shape and size, and are collinear with the centerline of the coplanar radiating patch 2. The first director 3 is directly above the coplanar radiating patch 2, and the second director 4 is directly above the first director 3.

[0035] The microstrip feed line 4 of the antenna consists of a rectangular patch and an irregularly rounded rectangular ring. The irregularly rounded rectangular ring is located above the rectangular patch and the two are connected.

[0036] Example 1

[0037] In this embodiment, the dielectric substrate 1 is rectangular in shape (see...). Figure 1-2 The material used is glass fiber epoxy resin copper clad laminate (FR-4), with a relative permittivity of 4.4. The dimensions of dielectric substrate 1 are 50mm × 33mm × 1.6mm (see...). Figure 3 The front side of the dielectric substrate 1 is printed with a coplanar radiating patch 2, a first director 3, a second director 4, and four radio frequency PIN diodes (SW1, SW2, SW3, SW4). The back side of the dielectric substrate 1 is printed with a microstrip feed line 5.

[0038] The coplanar radiation patch 2 consists of a main radiation patch and a parasitic radiation patch.

[0039] The main radiating patch consists of a coplanar stripline, two pairs of unequal-length rectangular double dipoles, and a truncated ground plane with a loaded rectangular branch. The coplanar stripline measures 31mm × 10mm and is located at the centerline of the front side of the dielectric substrate 1, 5mm away from the bottom edge of the substrate 1. The coplanar stripline has stepped slots that increase in width from bottom to top along the centerline of the dielectric substrate, with slot dimensions of 14mm × 0.3mm, 3mm × 0.8mm, and 14mm × 2mm from bottom to top. The two pairs of unequal-length rectangular double dipoles are connected to the coplanar stripline and are symmetrical about the centerline of the dielectric substrate 1. The upper rectangular double dipole measures 9.5mm × 4mm and is connected to the top of the coplanar stripline, while the lower rectangular double dipole measures 7.5mm × 4mm. The distance between the two pairs is 13mm. The dimensions of the truncated ground plane are 33mm × 5mm, and rectangular branches with dimensions of 6mm × 0.9mm are symmetrically loaded on the left and right sides near the dielectric substrate 1.

[0040] The parasitic radiation patch consists of two pairs of radiation patches, upper and lower. The upper parasitic radiation patch is composed of a 5mm × 2mm rounded rectangular patch and a 1mm × 0.9mm rectangular patch, positioned 1mm below the upper bipolar pole and 1.1mm from the left and right sides of the coplanar stripline. The lower parasitic radiation patch is a 5.9mm × 2mm rectangular radiation patch, placed vertically 1.1mm from the left and right sides of the lower bipolar pole.

[0041] The first director 3 and the second director 4 are rectangular patches of the same shape and size, each measuring 15mm × 2.5mm. The first director 3 is directly above the coplanar radiating patch 2, 2.5mm away from it. The second director 4 is directly above the first director 3, 3mm away from it. The second director 4 is 3.5mm away from the upper edge of the dielectric substrate 1.

[0042] The microstrip feed line 5 is composed of a rectangular patch connected to an irregularly rounded rectangular ring. The rectangular patch is 6mm × 3mm in size and is connected to the lower edge of the dielectric substrate 1. The distance between the rectangular patch and the lower edge of the dielectric substrate 1 is 12mm. The irregularly rounded rectangular ring is composed of rectangular patches with sizes of 10mm × 2mm, 8.5mm × 2mm and 10mm × 3mm. The top of the rectangular ring is rounded with radii of 1mm and 2mm respectively.

[0043] The RF PIN diodes (SW1, SW2, SW3, SW4) are Infineon's BAR50-02V series. These devices feature low on-resistance, an operating frequency of 10MHz-6GHz, a lead inductance of 0.6nH, an on-resistance of 3Ω, a turn-off parallel resistance of 5kΩ, a turn-off capacitance of 0.15pF, and an operating temperature range of -55 to 125℃. When all SW1, SW2, SW3, and SW4 are on, the antenna operates in the frequency range of 3.11-4.11GHz, covering the n78 band. When all SW1, SW2, SW3, and SW4 are off, the antenna operates in the frequency range of 3.97-5.01GHz, covering the n79 band. When SW1 and SW2 are on, and SW3 and SW4 are off, the antenna is a dual-band antenna, operating in the frequency ranges of 3.10-4.12GHz and 4.62-5.04GHz, operating within both the n78 and n79 bands.

[0044] Figure 3 This is a graph showing the return loss (S11) of the antenna in this embodiment. Figure 3 (a) Displays the return loss curve of the antenna operating in the n78 frequency band, with an effective operating bandwidth of 3.11-4.11 GHz; Figure 3 (b) Display the return loss curve of the antenna operating in the n79 frequency band, with an effective operating bandwidth of 3.97-5.01 GHz; Figure 3 (c) Display the return loss curve of the antenna operating in the n78 and n79 frequency bands. The effective operating bandwidth is 3.10-4.12GHz and 4.62-5.04GHz, which shows that the antenna of this embodiment can effectively operate in the 5G communication n78 and n79 frequency bands with good impedance bandwidth and realize the frequency reconfiguration function of three states.

[0045] Figure 4 , Figure 5 ,and Figure 6 These are the radiation patterns of the antenna in this embodiment at frequencies of 3.6 GHz and 4.8 GHz, respectively. In the figures, E-Plane / H-Plane refer to the electric or magnetic field. Figure 4 It can be seen that when the antenna operates in the n78 band, the gain at 3.6 GHz is 4.96 dBi; from Figure 5 It can be seen that when the antenna operates in the n79 band, the gain at 4.8 GHz is 6.74 dBi; Figure 6 (a) and Figure 6 (b) Far-field radiation patterns at 3.6 GHz and 4.8 GHz, respectively. Figure 6 As can be seen, when the antenna operates in the n78 and n79 frequency bands, the gain at 3.6 GHz is 5.09 dBi and the gain at 4.8 GHz is 6.41 dBi. This indicates that the antenna radiation pattern of this embodiment exhibits directional radiation and has good directional radiation characteristics. In the above three operating states, the antenna shows good directional radiation function, stable radiation performance and good gain performance, and has practical engineering value.

[0046] The foregoing has provided a detailed description of a single / dual-band reconfigurable microstrip quasi-Yagi antenna for 5G communication in the n78 and n79 frequency bands. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Modifications and improvements to this invention are possible without exceeding the concept and scope defined in the appended claims. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A single- or dual-band reconfigurable microstrip quasi-Yagi antenna, characterized in that: The substrate includes a dielectric substrate (1), on the front side of which a coplanar radiating patch (2), a first director (3), and a second director (4) are printed. The bottom of the coplanar radiating patch (2) is connected to the lower edge of the front side of the dielectric substrate (1). A first radio frequency PIN diode, a second radio frequency PIN diode, a third radio frequency PIN diode, and a fourth radio frequency PIN diode are disposed on the coplanar radiating patch (2). A microstrip feed line (5) is printed on the back side of the dielectric substrate, and the bottom end of the microstrip feed line (5) is connected to the lower edge of the back side of the dielectric substrate (1). The coplanar radiating patch (2) includes a main radiating patch and a parasitic radiating patch. The main radiating patch includes a coplanar stripline, two pairs of unequal-length rectangular double dipoles, and a truncated ground plane with loaded rectangular branches. The coplanar stripline has a stepped slit that is narrow to wide along the center line of the dielectric substrate from bottom to top. The parasitic radiating patch is divided into an upper parasitic radiating patch and a lower parasitic radiating patch. The upper parasitic radiating patch includes two rounded rectangles of the same shape and size, which are connected to the coplanar stripline of the main radiating patch on the left and right sides by a first radio frequency PIN diode and a second radio frequency PIN diode. The lower parasitic radiating patch includes two rectangles of the same shape and size, which are connected to the lower rectangular double dipole of the main radiating patch on the left and right sides by a third radio frequency PIN diode and a fourth radio frequency PIN diode. The main radiating patch and the two pairs of parasitic radiating patches are symmetrically placed on the left and right sides of the front side of the dielectric substrate (1) along the center line of the dielectric substrate. By setting the on and off states of four PIN diodes, the antenna can be reconfigured between single-band and dual-band modes.

2. The single- or dual-band reconfigurable microstrip quasi-Yagi antenna according to claim 1, characterized in that: The first director (3) and the second director (4) are rectangular patches of the same shape and size, and are collinear with the centerline of the coplanar radiating patch (2). The first director (3) is directly above the coplanar radiating patch (2), and the second director (4) is directly above the first director (3).

3. The single- or dual-band reconfigurable microstrip quasi-Yagi antenna according to claim 1, characterized in that: The microstrip feed line (5) consists of a rectangular patch and an irregularly rounded rectangular ring. The irregularly rounded rectangular ring is located above the rectangular patch and the two are connected.

4. The single- or dual-band reconfigurable microstrip quasi-Yagi antenna according to claim 1, characterized in that: The dielectric substrate (1) is rectangular in shape, with length, width and height dimensions of 50 mm × 33 mm × 1.6 mm. Its material is glass fiber epoxy resin copper clad laminate, and its relative permittivity is 4.

4.

5. The single- or dual-band reconfigurable microstrip quasi-Yagi antenna according to claim 1, characterized in that: The coplanar radiating patch (2), the first director (3), the second director (4), and the microstrip feed line (5) are all metal patches.

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