Ultra-wideband antenna based on C-shaped split ring structure

Abstract

The invention discloses an ultra-wideband antenna based on a C-shaped split ring structure. Belongs to the technical field of wireless communication antennas. The antenna is fed by a coplanar waveguide structure, and a trident frequency band broadening technology is used for better realizing broadband characteristics; the antenna structurally comprises a dielectric substrate, a C-type radiation patch and an annular ground structure, wherein the dielectric substrate is made of Tacoic TLY-5 (epsilon r is equal to 2.2, and tan delta is equal to 0.0009); the C-type radiation patch and the annular ground structure are positioned on the upper surface of the substrate; according to the antenna, a C-shaped bending structure is used as a radiation unit, so that a current path is effectively prolonged, and multimode resonance is realized while the size of the antenna is reduced; the return loss of the antenna in the frequency band of 4.5 GHz-19.4 GHz is smaller than-10 dB, the relative bandwidth reaches 125%, the working range of the antenna comprises a part of C wave band, all X wave band and Ku wave band, and the antenna has high gain (3.5-8.1 dBi) in the working frequency band; the antenna is wide in working range, simple in structure, easy to process and suitable for an ultra-wideband wireless communication system.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication antenna technology, specifically relating to a miniaturized ultra-wideband (UWB) microstrip antenna fed by a coplanar waveguide (CPW). Background Technology

[0002] With the rapid development of modern wireless communication systems, ultra-wideband (UWB) technology, due to its high data transmission rate, low power consumption, high security, and high resolution, has been widely applied in short-range high-speed communication, electronic warfare, radar detection, precision positioning, and medical imaging. Antennas, as front-end components of communication systems, are ubiquitous in daily life. The demands of UWB communication technology in both civilian and military fields are driving the continuous iteration of UWB antennas and related active devices. Planar UWB antennas meet the requirements of portable devices for miniaturization, integration, and low profile, making their research of significant practical value and a research hotspot.

[0003] Among various feeding methods, the coplanar waveguide (CPW) feeding structure is highly favored. Compared with traditional microstrip line feeding, the signal line and ground plane of the CPW structure are located on the same side of the dielectric substrate. It has significant advantages such as simple single-layer structure, easy integration with monolithic microwave integrated circuits and active devices, low dispersion characteristics, and low radiation loss, and is widely used in the design of broadband antennas. Summary of the Invention

[0004] In view of the shortcomings of the prior art, this invention proposes an ultra-wideband antenna based on a C-shaped open-loop structure, using coplanar waveguide feeding and trident bandwidth extension technology. This antenna uses a C-shaped bending structure to effectively extend the current path and achieve miniaturization; the use of a trident-shaped transition structure introduces multimode resonance and gradually varying impedance matching, successfully achieving continuous ultra-wideband coverage from 4.5 GHz to 19.4 GHz while maintaining a small planar size. Its operating range includes part of the C-band, all X-bands, and Ku-bands, and it exhibits high gain (3.5~8.1 dBi) within the operating frequency band.

[0005] The technical solution adopted in this invention is as follows:

[0006] An ultrawideband antenna based on a C-shaped open-loop structure includes: a dielectric substrate, a C-shaped radiating patch printed on the upper surface of the dielectric substrate, a coplanar waveguide feed line, a coplanar waveguide ground plane, and a trident-shaped bandwidth extension structure.

[0007] The coplanar waveguide feed line is located at the central axis of the upper surface of the dielectric substrate. One end of the line serves as a signal input port, and the other end is connected to the C-type radiating patch via the trident bandwidth extension structure.

[0008] The C-type radiating patch is designed as a non-closed, asymmetric open-loop structure, specifically composed of an outer ring bent arm, an inner ring bent arm, and a lateral connecting arm forming a topological shape resembling the letter "G". This structure utilizes the C-shaped bending design to extend the effective path of surface current, thereby reducing the lowest resonant frequency within a limited physical size and introducing multi-mode resonance.

[0009] Specifically, the C-shaped radiating patch includes a horizontally extending rectangular tuning stub on the lower left side near the feed port, with its characteristic dimensions defined as length Ls and width Ws. This rectangular tuning stub serves as a key impedance matching unit for the antenna, directly affecting the surface current distribution near the feed point. By finely adjusting the values ​​of length Ls and width Ws, the real and imaginary parts of the antenna's input impedance can be effectively corrected, eliminating impedance mismatch and thus further optimizing the return loss characteristics within the operating frequency band without changing the overall antenna size.

[0010] The trident-shaped bandwidth broadening structure is located at the connection between the feed line and the radiating patch. It consists of three parallel metal conductors, including a central main branch directly connected to the coplanar waveguide feed line and two auxiliary branches distributed on both sides of the main branch. This multi-segment structure makes the current distribution at the feed point more uniform. Furthermore, by forming multiple branch current paths through the three conductors, it introduces multiple local resonant points using the equivalent electrical lengths of different branches, and forms a gradually changing impedance transformation network at the feed point, thereby effectively suppressing in-band reflection spikes and extending the antenna's impedance bandwidth.

[0011] The coplanar waveguide ground plane has a ring-shaped structure, printed on the upper surface of the dielectric substrate and surrounding the C-shaped radiating patch. A coupling gap of width S is provided between the ground plane and the central conductor to adjust the characteristic impedance to 50 ohms. Furthermore, the ground plane has an asymmetrical structure about the central axis of the feed line; that is, the length LgL of the portion on the left side of the feed line is not equal to the length LgR of the portion on the right side (LgL≠LgR).

[0012] In summary, the present invention has the following beneficial effects:

[0013] 1. This invention effectively excites and fuses multiple resonant modes through the synergistic effect of a C-shaped bending structure and trident-style bandwidth extension technology. The antenna exhibits a return loss of less than -10dB and a relative bandwidth of up to 125% in the 4.5 GHz to 19.4 GHz frequency band. This operating frequency band covers part of the C-band, all of the X-band, and the Ku-band, solving the problem of insufficient bandwidth in high-frequency bands of traditional antennas.

[0014] 2. Employing a coplanar waveguide (CPW) feeding structure, all metal layers of the antenna are located on the same side of the dielectric substrate, eliminating the need for vias. This results in a simple structure that is easy to fabricate and facilitates monolithic integration with RF front-end circuitry. The C-shaped bend structure effectively utilizes substrate space, enabling miniaturized antenna design.

[0015] 3. The introduction of the trident structure forms a broadband impedance transformer, which enables the antenna to maintain smooth impedance matching over an extremely wide frequency band, effectively suppressing in-band VSWR spikes and improving communication quality.

[0016] 4. By introducing rectangular tuning stubs (Ls, Ws), the antenna possesses a more flexible impedance matching capability, effectively suppressing in-band VSWR spikes.

[0017] 5. The use of single-layer PCB technology and low-loss Taconic TLY-5 substrate reduces manufacturing costs while effectively reducing high-frequency dielectric loss and improving antenna radiation efficiency. Attached Figure Description

[0018] Figure 1 A perspective view of an ultra-wideband antenna based on a C-shaped open-loop structure provided for an embodiment of the present invention;

[0019] Figure 2 A top view of an ultra-wideband antenna based on a C-shaped open-loop structure provided in an embodiment of the present invention;

[0020] Figure 3 A side view of an ultra-wideband antenna based on a C-shaped open-loop structure provided in an embodiment of the present invention.

[0021] Figure 4 S11 of an ultra-wideband antenna based on a C-type open-loop structure provided in an embodiment of the present invention

[0022] Figure 5 A gain curve of an ultra-wideband antenna based on a C-type open-loop structure is provided for an embodiment of the present invention;

[0023] Figure 6 The radiation patterns of the E-plane and H-plane of an ultra-wideband antenna based on a C-type open-loop structure at 10.4 GHz are provided for embodiments of the present invention.

[0024] Figure 7 This is a schematic diagram of the lateral stub widths of an ultra-wideband antenna based on a C-shaped open-loop structure, provided as an embodiment of the present invention.

[0025] Explanation of reference numerals in the attached figures: 1. Asymmetric annular ground plane; 2. Semicircular radiating arm; 3. Trident structure; 4. Coplanar waveguide feed line; 5. Lateral connecting arm Xu; 6. Quarter-circular radiating arm; 7. Dielectric substrate; 8. Rectangular impedance tuning stub Ws. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0027] like Figure 1 Figure 2 As shown, the present invention provides an ultra-wideband antenna based on a C-shaped open-loop structure, which mainly consists of a dielectric substrate 7, C-shaped radiating patches (2, 5, 6, 8) printed on the upper surface of the dielectric substrate, a coplanar waveguide feed line 4, a coplanar waveguide ground plane 1, and a trident bandwidth extension structure 3.

[0028] In this embodiment, the dielectric substrate 7 is made of low-loss material Taconic TLY-5. Its relative permittivity εr = 2.2, dielectric loss tangent tanδ = 0.0009, and substrate thickness h = 0.762 mm. The overall geometric dimensions of the dielectric substrate 7 are designed to be 32 mm × 24 mm × 0.762 mm. This specific material and size combination aims to meet the requirements of miniaturization and high integration of antennas in portable wireless communication devices.

[0029] The antenna adopts a coplanar waveguide feeding mode, and the antenna's radiating patch and the ring ground are both located on the same side (upper surface) of the dielectric substrate 7.

[0030] The coplanar waveguide feed line 4 is located at the central axis of the dielectric substrate 7, and its width is designed to be Wf.

[0031] A uniform coupling gap, S, is provided between the coplanar waveguide feed line 4 and the coplanar waveguide ground plane 1 located on both sides of it. By precisely adjusting the ratio of Wf to S and combining it with the dielectric constant of the substrate, the characteristic impedance of the feed port is precisely matched to 50 ohms, thereby achieving low-loss transmission of radio frequency energy and reducing signal reflection.

[0032] The C-shaped radiating patch is the core radiating element of the antenna, exhibiting a non-closed "C"-shaped topology. This structure specifically consists of an outer ring bent arm 2, an inner ring bent arm 6, and a transverse connecting arm 5 connecting the two. The outer diameter D2 of the outer ring bent arm 2 and the inner diameter D1 of the inner ring bent arm 6 together determine the antenna's fundamental resonant frequency. This C-shaped bending structure effectively extends the path of surface current, enabling the antenna to excite lower-frequency resonant modes within limited physical dimensions, thus achieving miniaturization.

[0033] A trident-shaped bandwidth broadening structure 3 is provided in the transition region connecting the coplanar waveguide feed line 4 and the C-shaped radiating patch. This structure consists of three parallel metal conductors, including a main branch in the middle and auxiliary branches symmetrically distributed on both sides. This multi-branch feed structure introduces distributed coupling capacitance and inductance components at the feed point, constructing a gradually changing impedance transformation network, which significantly improves the impedance bandwidth of the antenna.

[0034] like Figure 1 As shown, a rectangular impedance tuning stub 8 extends from the lower left side of the C-shaped radiating patch near the feed port. The geometry of this stub is defined as length Ls and width Ws. This stub 8 can serve as an independent impedance tuning structure to optimize antenna bandwidth.

[0035] The coplanar waveguide ground plane 1 surrounds the C-shaped radiating patch, forming a semi-closed ring structure. This ring ground confines the current to flow along the ring path, increasing the equivalent electrical length, which is beneficial for introducing resonant points and impedance matching in the low-frequency band. In addition, the ring ground can suppress uncontrolled edge backflow and parasitic modes, and can improve the pattern stability to a certain extent.

[0036] To verify the effectiveness of the antenna described in this invention, the applicant used the full-wave electromagnetic simulation software CST to model and simulate the antenna.

[0037] Figure 4 Simulation curves of the return loss (S11) of the antenna in this embodiment as a function of frequency are presented. Simulation results show that the antenna bandwidth is 4.5 GHz to 19.4 GHz (percentage bandwidth 125%). Within this operating frequency band, the S11 curve exhibits multiple resonant points, confirming the multimode resonance mechanism of the C-type radiating patch and the broadband matching structure of the trident structure.

[0038] Figure 5 Simulation curves showing the gain of the antenna in this embodiment as a function of frequency are presented. Data shows that within the operating range of 4.5 GHz to 19.4 GHz, the antenna gain fluctuates between 3.5 dBi and 8.1 dBi.

[0039] Figure 6 The radiation pattern of the antenna in this embodiment at 9.4 GHz is shown when comparing the main polarization and cross polarization.

[0040] Figure 7The return loss (S11) of the rectangular tuning stub 8 under different widths Ws is presented. Simulation results show that when Ws is preferably 3mm, the antenna exhibits good impedance matching performance in the 4.5GHz~19.4GHz frequency band. This confirms that the rectangular tuning stub, as an independent tuning variable, plays a crucial role in correcting the input impedance at the feed and eliminating in-band reflection spikes.

[0041] In summary, the ultra-wideband antenna based on a C-shaped open-loop structure provided by this invention, through unique structural innovation, successfully solves the problem of ultra-wideband coverage while achieving device miniaturization, and has significant technological advancement and engineering application value.

Claims

1. An ultrawideband microstrip antenna based on a C-shaped open-loop structure, characterized in that, include: Dielectric substrate, C-type radiating patch printed on the upper surface of dielectric substrate, coplanar waveguide feed line, coplanar waveguide ground plane and trident bandwidth extension structure; One end of the coplanar waveguide feed line serves as a signal input port, and the other end is connected to the C-type radiating patch via a trident structure; The C-type radiating patch is a non-closed asymmetric open-loop structure, which is composed of an outer ring bent arm, an inner ring bent arm and a transverse connecting arm to form a topological shape similar to the letter "C". The C-type bent structure is used to extend the current path to achieve multimode resonance. The ground plane is a ring-shaped structure that covers the upper surface of the dielectric substrate and is located around the C-type radiating patch. The ring-shaped ground can regulate the current path and extend the equivalent electrical length, realize multi-resonance synthesis, thereby broadening the impedance bandwidth. At the same time, it can improve the stability of the radiation pattern and the polarization purity to a certain extent.

2. The ultra-wideband microstrip antenna based on a C-shaped open-loop structure according to claim 1, characterized in that: The outer contour of the C-shaped radiating patch is formed by an arc with a diameter of D2, and the inner contour of the inner ring bent arm is formed by an arc with a diameter of D1; this semi-circular structure provides the basic resonant point; the left side of the C-shaped radiating patch is formed by an arc with a radius of R2, and the inner contour of the inner ring bent arm is formed by an arc with a radius of R1; the rotation angle of the arc is theta2, and by adjusting this arc angle, the equivalent electrical length is changed, adding a new resonance in the low-frequency band; the opening of the C-shaped radiating patch has a gap Xu, and the lateral connecting arm has a width Lu, and by adjusting the gap Xu and the width Lu, the impedance characteristics of the antenna in the 4.5GHz to 19.4GHz frequency band are optimized.

3. The ultra-wideband microstrip antenna based on a C-shaped open-loop structure according to claim 1, characterized in that: The coplanar waveguide feed line is connected to the C-shaped radiating patch via a trident bandwidth broadening structure. The trident bandwidth broadening structure consists of three parallel metal conductors, including a central main branch directly connected to the coplanar waveguide feed line and two auxiliary branches distributed on both sides of the main branch. The multiple branches make the antenna feed more uniform. The three metal conductors form a multi-branch current path, and the equivalent electrical length of different branches introduces multiple local resonant points. A gradually changing impedance transformation network is formed at the feed point to suppress in-band reflection spikes and extend the impedance bandwidth of the antenna.

4. The ultra-wideband microstrip antenna based on a C-type asymmetric open-loop structure according to claim 1, characterized in that: The coplanar waveguide feeding structure consists of a central conductor strip on the upper surface of a dielectric substrate and metal ground planes on both sides of the central conductor strip. A coupling gap with a width of S is provided between the central conductor strip and the two metal ground planes. The width of the central conductor strip is Wf. By adjusting the width S of the coupling gap and the width Wf of the central signal conductor strip, the characteristic impedance of the feeding structure is matched to 50 ohms, and the two metal ground planes extend outward and merge with the ring ground structure, realizing low-loss energy transmission from the coplanar waveguide to the C-type radiating patch.

5. The ultra-wideband microstrip antenna based on a C-shaped open-loop structure according to claim 1, characterized in that: The ground plane has an asymmetrical structure; the length of the portion of the ground plane on the left side of the feed line is LgL, and the length of the portion on the right side of the microstrip feed line is LgR, and LgL≠LgR; By asymmetrically setting the lengths of the left and right sides of the ground plane, impedance matching can be optimized and the radiation pattern can be corrected.

6. The ultra-wideband microstrip antenna based on a C-shaped open-loop structure according to claim 1, characterized in that: The dielectric substrate is made of Taconic TLY-5 organic polymer material, with a relative permittivity εr of 2.2 and a dielectric loss tangent tanδ of 0.0009; the C-type radiating patch and the ground plane are both made of copper, with a conductivity of 5.8 x 10^7 S / m.

7. The ultra-wideband microstrip antenna based on a C-shaped open-loop structure according to claim 1, characterized in that: The antenna operates in a frequency band from 4.5 GHz to 19.4 GHz, with a relative bandwidth of 125%, and has a return loss of less than -10 dB within the operating frequency band, with a gain range of 3.5 dBi to 8.1 dBi.

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