A broadband multi-band communication antenna applied to a smart grid electric box

Abstract

The application discloses a kind of broadband multi-band communication antennas applied to intelligent power grid electric box, print on the medium substrate of front and back not intercommunication, front is the main body of radiation, including the butterfly-shaped metal radiation patch of central symmetry distribution, form dipole structure;Each patch surface is opened three parallel grooves, and evenly loaded resistance.Back loading concentric inner and outer polygon parasitic patch, hollow a ring between inner and outer patch.After power on, on the parasitic patch of back, induced current flows from patch center to outside, guided by polygon structure, increase effective electrical length, and introduce new resonant frequency.At the front of antenna, current spreads from center feed to outside, flows along patch edge and groove, increase effective electrical length of current, so that original high-frequency resonance point moves to low frequency direction and matching deepens;While low-frequency resonance point moves to high frequency direction, affect the change of resonant frequency.The application breaks the restriction of original physical size to resonant wavelength.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication and smart grid hardware terminals, specifically a broadband multi-band communication antenna applied to smart grid electrical boxes. Background Technology

[0002] With the development of the energy internet, smart grids have become an inevitable trend in the development of modern power systems. By integrating advanced sensing and measurement technologies, communication technologies, computer technologies, and control technologies, smart grids enable the intelligent, efficient, and reliable operation of power systems. In smart grids, every link from power generation, transmission, transformation, distribution to power consumption requires the efficient transmission and real-time interaction of massive amounts of data (such as grid status monitoring, advanced metering infrastructure (AMI), and distribution automation).

[0003] Generally speaking, a smart grid can be divided into three parts: Home Area Network (HAN), Neighborhood Network (NAN), and Wide Area Network (WAN).

[0004] HAN (Smart Controller) is a communication network established between smart meters and home appliances, enabling users to collect information about their electricity consumption and costs through home display devices. HAN requires relatively low bandwidth, therefore cost-effective communication technologies such as WiFi, Bluetooth, and ZigBee can be used.

[0005] The role of NAN is to establish a communication network between data concentrators and smart meters in a nearby area. It can use short-range communication technologies such as WiFi and wireless radio frequency networks to collect measurement data from smart meters and transmit the data to the data concentrator.

[0006] A WAN is a communication network established between a power company's data center and data concentrator. It is a two-way communication network with wide bandwidth and high throughput for long-distance data transmission. It typically uses low-cost but widely covered communication technologies, such as 4G-LTE / 5G, 2G-3G systems, and power line communication networks.

[0007] Antennas are devices that transmit and receive electromagnetic waves in wireless communication systems, and their performance directly determines the quality of the entire smart grid communication link. Whether it's an outdoor power pole monitoring terminal or an indoor smart meter, a high-performance antenna is required to ensure stable signal transmission.

[0008] However, in complex power grid environments, high voltage, high current, and strong electromagnetic interference are common, and wireless signals are often interfered with. A single communication technology cannot meet the needs of all aspects of the smart grid. Multi-band antennas provide redundant communication paths, and communication equipment can select the optimal frequency band and network access according to actual business needs to optimize the communication link and contribute to the reliability of smart grid communication.

[0009] In smart grid distribution automation, low-voltage distribution substation terminals, and advanced metering infrastructures (AMIs), smart boxes (such as switch boxes and meter boxes) typically employ a fully enclosed or semi-enclosed metal structure. To enable data acquisition, remote scheduling, and real-time status reporting from multiple sensors in the power grid, the internal communication terminals often require antennas that are compatible with both narrowband low-frequency IoT data transmission (such as around 0.88 GHz) and high-frequency broadband wireless low-power network transmission (such as the ultra-wideband band of 1.7 GHz to 2.7 GHz).

[0010] The services integrated within smart power distribution boxes are becoming increasingly complex, often requiring simultaneous access to the power grid, public IoT networks (such as NB-IoT / 4G / 5G), and local area networks (such as Wi-Fi / LoRa). Existing power grid antennas are mostly narrowband or single-band designs, unable to achieve efficient coverage of these multiple frequency bands within a single miniature antenna. To meet multi-mode communication requirements, multiple different antennas are typically installed, leading to significant space constraints within the power distribution box, low system integration, high susceptibility to electromagnetic interference, and a substantial increase in hardware costs.

[0011] Therefore, it is essential to design a broadband multi-band communication antenna that covers the main communication frequency bands of the smart grid. Summary of the Invention

[0012] To address the aforementioned issues, this invention proposes a broadband multi-band communication antenna for use in smart grid electrical boxes. This antenna achieves an ultra-wide operating frequency range and is compatible with multiple communication frequency bands, including dedicated power grids, public cellular networks (4G / 5G), and wireless local area networks. It reduces interference and space occupation caused by multiple antennas coexisting within the electrical box, improves system integration, and helps reduce hardware costs.

[0013] The broadband multi-band communication antenna is printed on a dielectric substrate with non-interconnected front and back sides. The front side is the main radiating element of the antenna, including a pair of centrally symmetrically distributed butterfly-shaped metal radiating patches located on both sides of the central feed area, forming a dipole structure. On the surface of each butterfly-shaped metal radiating patch, three parallel, slender slots are formed along the direction away from the center, running through the entire patch. The three slots from the center outward are named the first slot, the second slot, and the third slot, respectively; their distances from the center are 31mm, 35mm, and 50mm, respectively; the width of each slot is 1mm; in the second and third slots of each patch, five resistors are uniformly loaded, with a distance of 6mm between the resistors in the second slot and a distance of 12mm between the resistors in the third slot.

[0014] A polygonal parasitic patch is loaded on the back, consisting of two concentric inner and outer parts. The patch itself is composed of four centrally intersecting rectangles; the included angle between any two adjacent rectangles is 45°. A ring is cut out on the patch to divide it into inner and outer patches. The ratio of the radius of the inner patch to the radius of the outer patch is 0.5, and the ratio of the radius of the cut-out ring to the radius of the outer patch is 0.65.

[0015] The working principle of the antenna is as follows: After being powered on, the current diffuses outward from the center feed point. Due to the skin effect and the slotting effect, the current flows along the edge of the patch and the slot. The slotting structure effectively guides and changes the path of the surface current, improves the current distribution on the antenna surface, and increases the effective electrical length of the current. This causes the original high-frequency resonant point to move towards the low-frequency direction and deepen the matching. At the same time, the low-frequency resonant point moves towards the high-frequency direction, affecting the change of the resonant frequency.

[0016] On the parasitic patch on the back side, the induced current flows from the center of the patch outwards. Guided by the polygonal structure on its surface, the current cannot flow in a straight line but is forced to flow along the edge of the patch, increasing the effective electrical length and introducing a new resonant frequency. The formula is as follows:

[0017]

[0018] c is the speed of light. The effective dielectric constant of the dielectric substrate, The effective current length of the parasitic patch.

[0019] The effective current length of the parasitic patch flowing along the outer contour and diagonal of the gear is approximately 49.8 mm, and the effective dielectric constant is approximately 1.46. Substituting these values ​​into the formula, the newly introduced resonant frequency can be calculated. It is 2.49GHz.

[0020] The advantages of this invention are:

[0021] 1. The antenna described in this invention has ultra-wideband, multi-band operation, operating frequency band coverage of 0.8-2.7GHz, relative bandwidth of 113%, and good radiation performance with a maximum gain of 1.82dBi.

[0022] 2. By loading a polygonal parasitic patch, this invention can introduce a new resonant frequency based on the original resonant frequency, creating conditions for subsequent optimization of antenna bandwidth.

[0023] 3. This invention involves slotting the antenna surface and creating a high-frequency surface current on the metal patch surface. Unable to flow tangentially through the air slot, the current is forced to flow around the edge of the slot line, improving the current distribution on the antenna surface and increasing the actual effective physical path (i.e., electrical length) of the current on the antenna surface. The increase is significant, breaking the original physical size limitation on the resonant wavelength. Attached Figure Description

[0024] Figure 1 This is a structural diagram of a common bowtie antenna in the prior art;

[0025] Figure 2 This is a structural diagram of the broadband multi-band communication antenna of the present invention applied to a smart grid electrical box;

[0026] Figure 3 This is a schematic diagram of the parasitic patch on the back of the antenna described in this invention;

[0027] Figure 4 This is a schematic diagram of the loading resistor of the antenna described in this invention;

[0028] Figure 5 This is a surface current distribution diagram of the front radiating patch of the antenna described in this invention;

[0029] Figure 6 This is a surface current distribution diagram of the parasitic patch of the antenna described in this invention;

[0030] Figure 7 This is a diagram showing the effect of the antenna structure change described in this invention on the antenna S11 parameters;

[0031] Figure 8 The S11 parameters of the antenna described in this invention;

[0032] Figure 9 The voltage standing wave ratio (VSWR) of the antenna described in this invention;

[0033] Figure 10 The real and imaginary input impedances of the antenna described in this invention;

[0034] Figure 11 This is the three-dimensional gain pattern of the 0.88 GHz antenna described in this invention;

[0035] Figure 12 This is the three-dimensional gain pattern of the 2.45GHz antenna described in this invention;

[0036] Figure 13 This is the planar radiation pattern of the 0.88 GHz antenna described in this invention;

[0037] Figure 14 This is the planar radiation pattern of the 2.45GHz antenna described in this invention; Detailed Implementation

[0038] To facilitate a better understanding and implementation of the present invention by those skilled in the art, the present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the following description is merely illustrative of the technical principles of the present invention and does not constitute a limitation on the scope of protection of the present invention. Any equivalent substitutions or reasonable technical modifications made based on the concept of the present invention should be considered to fall within the scope of protection of the present invention.

[0039] This invention provides a broadband multi-band communication antenna for use in smart grid electrical boxes, based on, for example... Figure 1 The existing Bowtie antenna shown achieves an S11 parameter of -10dB across the entire operating frequency band (0.8-2.7GHz) by loading a polygonal parasitic patch on the back of the antenna radiating patch, slotting the radiating patch on the front, and loading a resistor in the slot; thus achieving an ultra-wide operating bandwidth; and exhibiting good impedance matching and radiation performance.

[0040] like Figure 2 As shown, the broadband multi-band communication antenna is printed on a dielectric substrate with non-interconnected front and back sides. The front side is the main radiating element of the antenna, including a pair of centrally symmetrically distributed butterfly-shaped metal radiating patches, located on both sides of the central feed area, forming a dipole structure. On the surface of each butterfly-shaped metal radiating patch, three parallel, elongated slots are formed along the direction away from the center, penetrating the entire patch. The three slots from the center outwards are named the first slot, the second slot, and the third slot, respectively. Figure 4 As shown, five resistors are evenly loaded in the second and third slots of each patch. The distance between the resistors in the second slot is 6 mm, and the distance between the resistors in the third slot is 12 mm.

[0041] like Figure 3 As shown, a polygonal parasitic patch is loaded on the back, consisting of concentric inner and outer parts. The patch itself is composed of four centrally intersecting rectangles; the included angle between any two adjacent rectangles is 45°. A ring is cut out on the patch, dividing it into inner and outer patches. The ratio of the radius of the inner patch to the radius of the outer patch is 0.5, and the ratio of the radius of the cut-out ring to the radius of the outer patch is 0.65.

[0042] The working principle of an antenna is as follows: after being powered on, such as Figure 5 As shown, the current in the front patch diffuses outward from the center feed point. Due to the skin effect and the slotting effect, the current flows along the edge of the patch and the slot. The slotting structure effectively guides and changes the path of the surface current, improves the current distribution on the antenna surface, and increases the effective electrical length of the current. This causes the original high-frequency resonant point to move towards the low-frequency direction and deepen the matching. At the same time, the low-frequency resonant point moves towards the high-frequency direction, affecting the change of the resonant frequency.

[0043] The high-frequency resonant point shifts towards lower frequencies because: according to the antenna's resonant frequency... The relationship with the electrical length is that the effective current length of the parasitic patch is increased by slotting, thereby shifting the original high-frequency resonant point to the left (low frequency direction).

[0044] The reason for the increase in resonant frequency in the low-frequency band is that in the low-frequency band, the overall capacitance of the antenna (mainly the edge parasitic capacitance and the capacitance between the patch and the ground plane) decreases due to the reduction in metal area and the discontinuity caused by the slot. According to the formula for calculating the resonant frequency:

[0045]

[0046] The slotting reduces the equivalent capacitance C. Even if the equivalent inductance L increases slightly, if the capacitance decreases by a larger margin, the product of LC in the denominator will still decrease overall, ultimately leading to an increase in the low-frequency resonant frequency f.

[0047] like Figure 6 As shown, on the parasitic patch on the back side, the induced current flows from the center of the patch outwards. Guided by the polygonal structure on its surface, the current cannot flow in a straight line but is forced to flow along the edge of the patch, increasing the effective electrical length and introducing a new resonant frequency. The formula is as follows:

[0048]

[0049] c is the speed of light. The effective dielectric constant of the dielectric substrate, The effective current length of the parasitic patch.

[0050] The effective current length of the parasitic patch flowing along the outer contour and diagonal of the gear is approximately 49.8 mm, and the effective dielectric constant is approximately 1.46. Substituting these values ​​into the formula, the newly introduced resonant frequency can be calculated. It is 2.49GHz.

[0051] The specific principle behind the generation of electromagnetic waves is as follows:

[0052] First, when the high-frequency surface current on the metal patch surface During periodic oscillations, according to the Ampere-Maxwell law, the conduction current and displacement current generate an alternating magnetic field H around the antenna:

[0053]

[0054] It is curl, which is a differential operator. It is the dielectric constant. It is the electric field strength.

[0055] At the same time, according to Faraday's law of electromagnetic induction, the alternating magnetic field further induces an alternating electric field. :

[0056]

[0057] It is the permeability;

[0058] Then, alternating electric field Coupled with the alternating magnetic field H, an alternating electromagnetic field is formed around the antenna; this field can be solved using the method of separation of variables, special functions, or numerical calculation methods (such as FDTD, finite element method). And H.

[0059] Finally, when the electromagnetic field breaks free from the conductor's constraint and propagates into free space, it forms an electromagnetic wave, the direction of energy transmission and its power density of which can be represented by the Poynting vector:

[0060]

[0061] Where S represents the electromagnetic power flux density per unit area, and its direction is the direction of electromagnetic energy propagation.

[0062] Example:

[0063] The antenna is printed on a Neltec NY9220(IM)(tm) dielectric substrate. The main radiating element of the antenna consists of a pair of centrally symmetrically distributed butterfly-shaped metal radiating patches located on either side of the central feed region, forming a dipole structure. The polygonal metal patch on the back of the dielectric substrate is a parasitic patch, designed to introduce a second resonant frequency.

[0064] On the surface of each butterfly-shaped metal radiating patch on the front side, three parallel, slender slots are cut away from the center: these three slots are named the first slot, the second slot, and the third slot, respectively. Parameter scanning in simulation software revealed that the distances of the three slots from the center are 31mm, 35mm, and 50mm, respectively; the slot width is 1mm; and the length is the width of the butterfly patch at the current position, extending through the entire patch. Five 50Ω resistors are uniformly loaded in the second and third slots of the left and right patches.

[0065] After power is applied, the current diffuses outward from the center feed point. As the current flows from the center to the left edge of the patch, the current on the right patch flows from the right edge towards the center. Due to the slotting effect, the current also flows along the slot gaps. On the parasitic patch on the back side, since the front and back sides of the substrate are not interconnected, the induced current flows from the center of the patch outward.

[0066] The antenna simulation was performed using HFSS electromagnetic simulation software. The antenna substrate was made of Neltec NY9220(IM) (tm), with dimensions of 120×182mm and a thickness of 3.15mm. The antenna arm length was 45.54mm, the circumcircle radius was 60mm, and the antenna width was 108.54mm. The radius of the parasitic patch was 11mm. The slot width was 1mm, and 20 resistors, each 50Ω, were applied. The antenna angle α was 100°. The spacing between the two butterfly patches was 2.28mm, with an excitation device placed in the middle.

[0067] The specific design process of the antenna is as follows:

[0068] Step 1: Load a parasitic patch onto the back of the dielectric substrate of an existing conventional bowtie antenna. The parasitic patch is located directly below the gap between the two front radiating patches.

[0069] like Figure 2 The yellow patch shown is a butterfly-shaped radial patch, and the blue polygonal patch on the back is a parasitic patch;

[0070] The parasitic patch is composed of four rectangular patches of 22mm×7mm in a centrally symmetrical arrangement. During scanning, two rectangles were set to form a cross-shaped patch, three rectangles to form a star-shaped patch, and four rectangles to form a gear-shaped patch for analysis. Finally, it was found that the gear-like hollow polygonal topology structure had the best effect.

[0071] The radial length ratio of the inner patch to the outer patch is 0.5, and the ratio of the cutout between two adjacent rectangular patches to the outer patch is 0.65. The parasitic patch itself is not directly connected to the excitation source; its energy comes entirely from the spatial near-field electromagnetic coupling of the front main radiating patch.

[0072] The parasitic patch introduces a new resonant frequency to the antenna, which is 2.49 GHz. At this point, the antenna evolves into a dual-band antenna, operating at a low frequency of 0.78 GHz and a high frequency of 2.49 GHz, achieving the initial dual-band configuration. However, the mid-band 1.0-2.2 GHz is still in an impedance mismatch state (S...). 11 >-10dB).

[0073] Step 2: In order to broaden the bandwidth and improve the performance of the mid-band, slots are cut at appropriate positions on the radiating patch on the front of the antenna along the direction away from the center, with three slots on each of the left and right patches to maintain the symmetry of the two patches.

[0074] A narrow, elongated slot (groove) 1 mm wide is formed on the butterfly-shaped patch on the front of the antenna, and three slots are formed on each of the two radiating patches along the direction away from the center. According to the electromagnetic field boundary conditions, the high-frequency surface current J on the metal patch surface... surf Unable to flow tangentially through the air slot, it is forced to flow around the edge of the slot line. This behavior reduces the actual effective physical path of the current on the antenna surface (i.e., the electrical length L). effective The increase is significant, breaking the original physical size limitation on the resonant wavelength.

[0075] The resonant frequency f of the antenna is related to its electrical length by the following:

[0076]

[0077] The L was increased by slotting. effective This causes the original high-frequency resonant point to move to the left (in the low-frequency direction) and deepen the matching; at the same time, the low-frequency resonant point moves to the right, providing a foundation for the subsequent integration of multiple frequency bands.

[0078] Step 3: Load 50-ohm resistors into the two outer slots on each side of the two radiating patches on the front of the antenna. The number of resistors loaded on both sides should be the same to maintain symmetry. The number of resistors loaded in each slot should be 5.

[0079] Traditional broadband antennas may exhibit a large reflection coefficient in certain frequency bands due to input impedance mismatch with feed line impedance, resulting in a noticeable standing wave phenomenon. Introducing a lumped resistance R... L Subsequently, an additional damping effect is generated inside the antenna, which can convert some of the reflected energy into heat loss for dissipation, thereby suppressing the formation of standing waves, improving impedance matching characteristics and widening the operating bandwidth.

[0080] From the perspective of the quality factor Q, the addition of resistance reduces the system Q value of the antenna:

[0081]

[0082] Where P radiated This represents the power consumed by the resistor.

[0083] Step 4: Double the thickness of the original dielectric substrate and set the antenna angle α as a variable, then perform a parameter scan. The antenna angle affects the low-frequency resonant frequency of the antenna; the larger the angle, the lower the resonant frequency. Increasing the dielectric substrate thickness h helps enhance the electric field spread effect at the patch edge, increases radiative conductivity, and reduces the antenna quality factor Q, thereby reducing the ratio between stored and radiated energy, ultimately widening the antenna's impedance bandwidth. On the other hand, the antenna angle α directly affects the tapered impedance characteristics of the Bowtie antenna, which can be approximated as:

[0084]

[0085] As the antenna angle increases, the characteristic impedance gradually decreases, and the impedance transition becomes smoother, which helps improve impedance matching characteristics over a wide bandwidth. A good effect is achieved when the angle is 100°.

[0086] The S11 parameter varies with the antenna structure as follows: Figure 7 As shown.

[0087] The results indicate that:

[0088] like Figure 8-9 As shown, the designed antenna achieved continuous impedance matching within the ultra-wideband 0.78-2.9 GHz, reaching the final ultra-wideband design goal. Within the 0.78-2.9 GHz range, S11 < -10 dB, VSWR (Voltage Standing Wave Ratio) < 2. Figure 10 As shown, analysis of the antenna's input impedance characteristics reveals that the antenna performs better in the high-frequency range and slightly worse in the low-frequency range. Figure 11 and Figure 13 As shown, the antenna has a maximum gain of 1.26 dBi at 0.88 GHz, exhibits omnidirectional radiation characteristics, and reaches its maximum gain in the horizontal direction. Figure 12 and Figure 14 As shown, the radiation pattern of the 2.45GHz antenna is slightly distorted, but it still has omnidirectional radiation characteristics and a maximum gain of 1.82dBi. Compared with the low frequency band, the maximum gain of the high frequency band is improved.

[0089] Finally, it should be noted that although this specification has described the invention in detail with reference to specific embodiments, these embodiments are only used to better illustrate the core technical concept of the invention. Any modifications, adjustments, or variations made using equivalent technical means within the scope of the invention should be considered to fall within the protection scope of the invention.

Claims

1. A broadband multi-band communication antenna for use in smart grid electrical boxes, characterized in that, The antenna is printed on a dielectric substrate with non-interconnected front and back sides. The front side is the main radiating element of the antenna, including a pair of centrally symmetrically distributed butterfly-shaped metal radiating patches, located on both sides of the central feed area, forming a dipole structure. On the surface of each butterfly-shaped metal radiating patch, three parallel, slender slots are formed along the direction away from the center, running through the entire patch. The three slots from the center outward are named the first slot, the second slot, and the third slot, respectively. In the second and third slots of each patch, a resistor is uniformly loaded. The back is loaded with a polygonal parasitic patch, which consists of two concentric inner and outer parts, and is composed of four rectangles that intersect at the center; a ring is cut out between the inner and outer patches, and the cut-out ring divides the patch into the inner and outer parts.

2. The antenna as described in claim 1, characterized in that, The distances from the center of the first, second, and third slots are 31mm, 35mm, and 50mm, respectively; the width of each slot is 1mm.

3. The antenna as described in claim 1, characterized in that, There are 5 load resistors. The distance between the resistors in the second slot is 6mm, and the distance between the resistors in the third slot is 12mm.

4. The antenna as described in claim 1, characterized in that, The included angle between two adjacent rectangles is 45°.

5. The antenna as described in claim 1, characterized in that, The ratio of the inner patch radius to the outer patch radius is 0.5, and the ratio of the radius of the cutout ring to the outer patch radius is 0.

65.

6. The antenna as claimed in claim 1, characterized in that, After power is applied, the current diffuses outward from the center feed point and flows along the patch edge and slot. The slot structure effectively guides and changes the path of the surface current, improves the current distribution on the antenna surface, and increases the effective electrical length of the current. This causes the original high-frequency resonant point to move towards the low-frequency direction and deepen the matching; at the same time, the low-frequency resonant point moves towards the high-frequency direction, affecting the change of the resonant frequency. On the parasitic patch on the back side, the induced current flows from the center of the patch outwards. Guided by the polygonal structure on its surface, the current cannot flow in a straight line but is forced to flow along the edge of the patch, increasing the effective electrical length and thus introducing a new resonant frequency. The formula is as follows: c is the speed of light. The effective dielectric constant of the dielectric substrate, The effective current length of the parasitic patch.

7. The antenna as claimed in claim 6, characterized in that, The effective current length of the parasitic patch flowing along the outer contour and diagonal of the gear is approximately 49.8 mm, and the effective dielectric constant is approximately 1.

46. Substituting these values ​​into the formula, the newly introduced resonant frequency can be calculated. It is 2.49GHz.

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