Dual-frequency directional PCB antenna

Abstract

The invention discloses a double-frequency directional PCB (printed circuit board) antenna, and relates to the technical field of wireless communication, in particular to a double-frequency directional PCB antenna, which is characterized in that a pair of planar inverted-F antennas are symmetrically arranged on a printed circuit board with the size of 50mm * 35mm, and the planar inverted-F antennas work in a dipole mode and share a second grounding metal layer to realize directional radiation. Each antenna unit comprises a main radiation arm with the length of 22.5 mm and used for generating 2.4 GHz resonance; the tail end of the branch radiation arm is connected with the branch radiation arm which is 5.7 mm long and is used for generating 5GHz resonance; a short-circuit column with double through holes connected in parallel is connected with the grounding layer; electromagnetic coupling of the 50-ohm microstrip feeder line is realized through a coupling gap with the length of 15mm and the width of 0.25 mm on the grounding layer. The standing-wave ratios of the antenna in 2.4 GHz and 5GHz frequency bands are not greater than 2, the gains respectively reach 2-3dBi and 5-7dBi, and the antenna is suitable for an MIMO wireless communication system with the IEEE 802.11 b / g / n / ac / ax standard.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, specifically to a dual-band directional PCB antenna. Background Technology

[0002] With the continuous improvement of broadband access speeds and the widespread adoption of applications such as smart homes, high-definition video streaming, and online office work, users have increasingly higher requirements for the coverage, connection stability, and transmission speed of wireless local area networks (WLANs). Currently, Wi-Fi routers in home and small-to-medium-sized office environments generally use built-in or external omnidirectional antennas, whose radiation pattern is approximately circular in the horizontal plane, theoretically achieving 360° signal coverage in free space. However, in actual residential or office scenarios, omnidirectional antennas have a series of inherent defects that seriously affect the user experience.

[0003] First, there are significant limitations in installation and deployment. Since fiber-to-the-home (FTTH) information panels, weak current boxes, or operator-reserved interfaces are typically located in corners or near walls, routers often cannot be deployed in the center of the space. This results in a significant waste of omnidirectional antenna radiation energy in non-target directions (such as outdoors or in corridors), leading to insufficient signal strength in the effective indoor coverage area. Furthermore, walls, furniture, and other obstacles further cause signal reflection and attenuation, resulting in a substantial difference between the actual coverage and the ideal model.

[0004] Secondly, there are significant differences in performance between the two frequency bands. The 2.4GHz band, due to its longer wavelength, has a relatively strong ability to penetrate walls and other obstacles, making it suitable for medium- to long-distance coverage. However, this band is congested and susceptible to co-channel interference from microwave ovens, Bluetooth devices, and other Wi-Fi networks, severely impacting communication quality. While the 5GHz band offers more available channels and less interference, supporting higher data transmission rates, its shorter wavelength results in more significant signal attenuation when penetrating walls or over longer distances, limiting its coverage in practical environments.

[0005] Furthermore, omnidirectional antennas also suffer from energy efficiency issues. Their uniform radiation in all directions results in a significant amount of radio frequency power being wasted in areas that don't need coverage. This not only reduces signal strength in the target area but may also increase the risk of the network being spied on or interfered with. For key areas in a home (such as the living room, study, and bedroom), omnidirectional antennas struggle to provide targeted signal enhancement, impacting the wireless experience in these critical areas.

[0006] To overcome these problems, the industry has attempted to use directional antennas to improve signal strength in the target direction. However, traditional directional antennas are often large and complex in structure, making them difficult to integrate into compact devices such as home routers. Furthermore, directional antennas supporting dual-band operation (2.4GHz and 5GHz) often employ multi-antenna combinations or external reflectors, which not only increases cost but also complicates installation and debugging. Therefore, achieving a simple, cost-effective antenna solution with good dual-band directional radiation characteristics within a limited space has become a significant challenge in current WLAN device design. Summary of the Invention

[0007] The purpose of this invention is to provide a dual-band directional PCB antenna. By employing a pair of planar inverted-F antennas (PIFA) arranged symmetrically in a dipole manner and sharing a ground plane to form a directional radiation structure, and utilizing the combination of the main radiating arm and the branch radiating arm, dual-band coverage of 2.4GHz and 5GHz is achieved. This solves the problems of insufficient directionality, low gain, and poor impedance matching of existing antennas in dual-band operation, thereby improving the signal coverage quality and transmission stability of wireless communication systems and meeting the needs of modern Wi-Fi devices for high-performance integrated antennas.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a dual-frequency directional PCB. The antenna comprises a pair of planar inverted-F antennas (PIFAs) arranged symmetrically on the printed circuit board. The pair of PIFAs are arranged in a dipole configuration and share a ground metal layer disposed on the second layer of the printed circuit board to form directional radiation. Each PIFA includes: a main radiating arm disposed on the first layer of the printed circuit board with a length of 22.5 mm, used to generate a first-order resonance in the 2.4 GHz band; at least two shorting posts with a diameter of approximately 0.3 mm, which vertically penetrate the printed circuit board and electrically connect one end of the main radiating arm to the ground metal layer; a microstrip feed line disposed on the first layer with a characteristic impedance of 50 ohms; a coupling slot disposed on the ground metal layer, located directly above the microstrip feed line, with a length of 15 mm and a width of 0.25 mm, used to achieve electromagnetic coupling between the microstrip feed line and the main radiating arm; and a branch radiating arm disposed at the end of the main radiating arm with a length of 5.7 mm, used to provide resonance in the 5 GHz band. This structure achieves dual-band directional radiation characteristics in a compact size through a symmetrical PIFA dipole arrangement and coupled feeding method. It also effectively reduces the local inductance of the antenna by using a multi-short post design, so that the main radiating arm can achieve the required electrical length within a limited size.

[0009] Furthermore, the overall dimensions of the printed circuit board are 50mm x 35mm. This specific size ensures a highly compact antenna structure, allowing it to be directly installed inside the housing of a home router or in space-constrained environments such as a low-voltage distribution box, while maintaining the antenna's radiation performance in the 2.4GHz and 5GHz frequency bands, facilitating integration into consumer electronics products.

[0010] Furthermore, the arrangement of the pair of PIFAs results in an antenna gain of 2-3 dBi in the 2.4 GHz band and 5-7 dBi in the 5 GHz band. This gain configuration allows the 2.4 GHz band to meet the needs of both wall-penetrating coverage and medium-to-long-distance connections, while the 5 GHz band effectively compensates for the attenuation of high-frequency signals during transmission through its higher directional gain, thereby improving overall coverage and data transmission rate.

[0011] Furthermore, the input VSWR of the antenna is no greater than 2 in both the 2.4 GHz and 5 GHz bands. A low VSWR indicates that the antenna has good impedance matching characteristics across all operating frequency bands, which helps reduce signal reflection, improve energy transmission efficiency, and ensure the stability and reliability of the wireless communication link.

[0012] Furthermore, the printed circuit board uses a substrate with a dielectric constant ε≈3.0 and a loss tangent tanδ≤0.0031. Selecting this type of low-loss substrate helps reduce the transmission loss of high-frequency signals in the medium, ensuring antenna efficiency. At the same time, these material parameters are compatible with conventional AW300 processes, facilitating mass production and quality control of the antenna.

[0013] Furthermore, the branch radiating arm is coupled in the same direction as the main radiating arm, forming a λ / 2 composite mode in the 5GHz band. This coupling mode enables the antenna to achieve a high peak gain of approximately 6 dBi in the 5GHz band, thereby effectively enhancing the signal strength within the directional main lobe range of this band and improving the coverage capability of the high-frequency band.

[0014] Furthermore, the at least two short-circuit posts are a dual-via parallel structure to reduce local inductance. Compared to a single short-circuit post design, the parallel short-circuit post structure can significantly reduce the parasitic inductance of the current path. This not only helps to achieve an equivalent electrical length of λ / 4 within a limited area, but also extends the operating bandwidth of the antenna.

[0015] Furthermore, the forward half-power beamwidth of the pair of PIFAs is 350°-360° in the 2.4GHz band and 120°-160° in the 5GHz band. This beamwidth characteristic allows the 2.4GHz band to have near omnidirectional coverage for better wall penetration, while the 5GHz band has a narrower directional beam that concentrates energy radiation on the target area, improving energy utilization.

[0016] Furthermore, the width of the microstrip feed is 0.25 mm. This specific width is one of the key parameters for achieving a 50-ohm characteristic impedance, ensuring good impedance matching between the feed and the RF front-end circuitry and reducing signal integrity degradation caused by impedance mismatch.

[0017] Furthermore, the antenna design conforms to the IEEE 802.11b / g / n / ac / ax specifications and can be used in combination with 2x2 or 4x4 MIMO routers. This compatibility allows the antenna to be seamlessly integrated into existing multiple-input multiple-output wireless systems, forming directional coverage arrays to further improve network capacity and coverage performance, making it suitable for home, SOHO, and other scenarios.

[0018] This invention provides a dual-band directional PCB antenna, which has the following advantages: Significantly Improves Signal Quality and Coverage Uniformity in Target Areas: This invention employs a pair of symmetrical planar inverted-F antennas (PIFAs) arranged in a dipole configuration and sharing a ground plane to form directional radiation, effectively altering the energy distribution pattern of traditional omnidirectional antennas. This design achieves a gain of 2-3 dBi in the 2.4 GHz band, balancing wall penetration coverage with medium-to-long-distance connectivity requirements; simultaneously, the gain in the 5 GHz band is significantly increased to 5-7 dBi, effectively compensating for the inherent drawback of high signal attenuation in this band. This differentiated directional gain strategy concentrates radio frequency energy in key indoor areas requiring coverage (such as living rooms and studies), rather than wasting it on walls or outdoors. This significantly improves signal strength, connection stability, and overall coverage uniformity in target areas within a real-world home environment, resolving coverage blind spots caused by router installation location limitations.

[0019] Achieving a balance between high performance and miniaturized size for easy integration and application: This invention realizes dual-band directional antenna functionality on an extremely compact 50mm x 35mm printed circuit board through innovative structural design. The key lies in the use of at least two 0.3mm diameter short-circuit posts (dual vias in parallel) to connect the main radiating arm to the ground plane in each PIFA unit. This structure reduces local inductance, allowing the antenna arm length to achieve the required electrical length (λ / 4 resonance) within a limited size, thus overcoming the limitations of traditional antennas with larger dimensions. This miniaturized design allows the antenna to be directly integrated into the housing of a home router or a low-voltage box, or used as an external module, greatly facilitating the compact design of consumer electronics products and resolving the contradiction between high-performance antennas and the need for device miniaturization.

[0020] This invention optimizes bandwidth and impedance matching through structural innovation, enhancing operational stability. It employs an electromagnetic coupling feeding method, specifically by creating a coupling slot of a specific size (15mm long, 0.25mm wide) in the ground layer, allowing the energy from the microstrip feed line to be coupled to the upper radiating arm. Compared to direct feeding, this method provides additional impedance matching freedom, particularly beneficial for fine-tuning the input impedance in the 5GHz high-frequency band. Combined with the bandwidth-extending effect of the dual short-circuit pillar structure, this ultimately ensures a good matching state with an input VSWR (VSWR) of no more than 2 in both the 2.4GHz and 5GHz operating frequency bands. Excellent impedance matching means that more signal energy is effectively radiated rather than reflected back into the circuit, thereby reducing energy loss and improving antenna efficiency and signal transmission stability.

[0021] Simplified structure to reduce manufacturing costs and improve production consistency: This invention adopts a single-piece PCB design, simultaneously achieving 2.4GHz and 5GHz dual-band antenna functionality on a single circuit board through printed circuit technology, eliminating the need for additional duplexers or discrete multiple antennas. The AW300 process used (dielectric constant ε≈3.0, loss tangent tanδ≤0.0031) is a conventional and mature PCB manufacturing process, which helps control material costs and ensure high yield rates in mass production. The antenna structure has no external feed lines or complex mechanical assembly components, significantly reducing material costs and assembly complexity. This gives this high-performance antenna solution a cost advantage for large-scale commercial applications, while the structural consistency also helps ensure uniform product performance.

[0022] Enhancing network capacity and security with strong technological evolution potential: The directional radiation characteristic of this invention concentrates energy in the target direction, not only improving signal strength but also reducing radiation to non-target directions (such as neighboring homes or outdoors). This helps reduce co-channel interference and also reduces signal leakage from the network itself, thereby improving the privacy and anti-interference capabilities of the wireless network to a certain extent. Furthermore, the antenna design complies with mainstream IEEE 802.11b / g / n / ac / ax protocol standards and can be seamlessly combined with commercially available 2x2 or 4x4 MIMO router platforms to form a stronger directional coverage array, further improving network capacity. Its basic design architecture (such as symmetrical PIFA and coupled feeding) is scalable and can be adapted to future higher frequency bands such as 6GHz by fine-tuning the feeder or resonant arm length, demonstrating strong technological evolution potential. Attached Figure Description

[0023] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a linear graph of the standing wave ratio (VSWR) of this invention; Figure 3 This is the 2.4GHz gain diagram of the present invention; Figure 4 This is the 5GHz gain diagram of the present invention; Figure 5 This is a linear graph of the antenna efficiency of the present invention; Figure 6 This is a linear graph of the return loss of the present invention. Detailed Implementation

[0025] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses consistent with some aspects of this disclosure as detailed in the appended claims.

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] How to use: 1. Installation Preparation First, determine the installation location, typically inside the home router casing, inside the low-voltage box, or in a designated area for the external antenna module. Ensure the installation surface is flat and unobstructed, and leave 50mm x 35mm of installation space to accommodate the entire antenna.

[0028] 2. Circuit board fixing Secure the printed circuit board 1 to the target device using screws or clips, taking care to avoid bending or squeezing. Ensure that the substrate dielectric constant of the printed circuit board 1 is ε≈3.0 and the loss tangent tanδ≤0.0031 to maintain stable antenna performance.

[0029] 3. Symmetrical PIFA pair arrangement On printed circuit board 1, a pair of planar inverted-F antennas PIFA2 are symmetrically arranged in a dipole configuration. Each PIFA includes a main radiating arm 3, a branch radiating arm 7, at least two shorting posts 4, a microstrip feed line 5, and a coupling slot 6. A directional radiation mode is formed by sharing a second ground metal layer.

[0030] 4. Main radiating arm setup The main radiating arm 3, 22.5 mm long, is located on the first layer and is used to generate a first-order resonance in the 2.4 GHz band. During installation, ensure that the end of the main radiating arm 3 is connected to the branch radiating arm 7, which is 5.7 mm long, to provide resonance in the 5 GHz band.

[0031] 5. Short-circuit post connection Using at least two shorting posts 4, 0.3 mm in diameter, perpendicularly penetrating the printed circuit board 1, one end of the main radiating arm 3 is electrically connected to the ground metal layer. This dual-via parallel structure reduces local inductance and optimizes bandwidth.

[0032] 6. Microstrip feeder and coupling The microstrip feed line 5 is located on the first layer, with a characteristic impedance of 50 ohms and a width of 0.25 mm. The coupling gap 6 is located on the ground metal layer, with a length of 15 mm and a width of 0.25 mm, and is positioned directly above the microstrip feed line 5 to achieve electromagnetic coupling feeding.

[0033] 7. Frequency band tuning By coupling the main radiating arm 3 and the branch radiating arm 7 in the same direction, a λ / 2 composite mode is formed in the 5GHz band, ensuring a gain of 5-7 dBi; the gain in the 2.4GHz band is 2-3 dBi. Adjustments are made to ensure that the input VSWR is no greater than 2.

[0034] 8. Beamwidth optimization Check the forward half-power beamwidth of a pair of PIFA2s: 350°-360° in the 2.4GHz band and 120°-160° in the 5GHz band, to ensure directional coverage of the target area.

[0035] 9. MIMO Integration Combining antennas with 2x2 or 4x4 MIMO routers, conforming to IEEE 802.11b / g / n / ac / ax specifications, improves the coverage uniformity of multi-antenna systems.

[0036] 10. Performance Verification After powering on, a network analyzer was used to verify whether the dual-band VSWR and gain met the requirements. Once the signal was stable, it was put into daily use.

[0037] Example 1: Directional Coverage Enhancement for Home Wireless Routers This embodiment provides a dual-band directional PCB antenna designed specifically for home wireless routers, aiming to effectively improve signal coverage and wall penetration in a specific direction. In implementation, a printed circuit board 1 is first prepared, its overall size adapted to the internal space of a common router. On the printed circuit board 1, a pair of planar inverted-F antennas (PIFAs 2) arranged in a dipole configuration are precisely fabricated, ensuring structural symmetry. These PIFAs share a complete ground metal layer on the second layer of the printed circuit board 1, thus forming a directional radiation mode that concentrates energy forward rather than scattering it evenly in all directions.

[0038] The specific structure of each PIFA 2 is as follows: A main radiating arm 3 is etched into the first layer, its length carefully designed specifically for exciting a first-order resonance in the 2.4 GHz band, where signals have longer wavelengths and better diffraction capabilities. Near the ground end of the main radiating arm 3, at least two shorting posts 4 are placed. These vertically penetrating metallized vias reliably connect the main radiating arm 3 to the ground metal layer of the second layer, forming a stable reference ground. A microstrip feed line 5 is also arranged on the first layer, its characteristic impedance matched for direct connection to the standard interface of the router's internal RF circuitry. To achieve efficient power feeding and avoid parasitic effects from direct soldering, a narrow coupling slot 6 is created on the ground metal layer corresponding to the microstrip feed line 5. Energy is excited to the main radiating arm 3 through electromagnetic coupling via this slot. Furthermore, a branch radiating arm 7 extends from the end of the main radiating arm 3, its length designed to generate resonance in the 5 GHz band, a band with clean channels and high data rates.

[0039] This antenna module is integrated into the router housing, typically two installed side-by-side to form a basic 2x2 MIMO system. After installation, the antenna exhibits near-omnidirectional but slightly forward-leaning beam characteristics in the 2.4GHz band, effectively covering most areas of the home; while in the 5GHz band, it displays more pronounced directional characteristics, with a narrower beamwidth and higher gain, making it particularly suitable for targeting key areas requiring high-speed wireless access, such as studies and bedrooms. In this way, the router achieves superior directional signal quality compared to ordinary omnidirectional antennas in both bands, meeting the modern home network's demand for both wide coverage and high speed.

[0040] Example 2: Directional Communication Node for Industrial IoT Gateways This embodiment relates to a dual-band directional PCB antenna for use in industrial IoT gateways. Its core requirement is to establish a stable and reliable dual-band wireless link in complex electromagnetic environments. In implementation, a special substrate with stable dielectric constant and extremely low loss is selected to fabricate the printed circuit board 1. A pair of planar inverted-F antennas (PIFAs) 2 are constructed on the board. They are arranged in a strictly symmetrical structure and dipole configuration, sharing a large ground metal layer. This ground layer not only provides an electrical reference but, more importantly, works in conjunction with the pair of PIFAs to form strong back-end suppression and forward radiation characteristics, i.e., directional radiation functionality.

[0041] The functions of each antenna component are clearly defined: the main radiating arm 3 is responsible for generating a first-order resonance covering the frequency band commonly used in industrial IoT; low-inductance grounding is achieved through at least two parallel short-circuit posts 4, improving the antenna's mechanical and electrical stability; energy is received through a microstrip feed line 5 and coupled to the radiating arm in a non-contact manner through the coupling slot 6 directly above it, providing good bandwidth performance. The branch radiating arm 7 extends from the end of the main radiating arm 3 and works in conjunction with it to excite effective resonant modes at higher frequency bands.

[0042] When deployed in industrial settings, this antenna module is sealed and mounted on the outside of the gateway device's metal casing, with its radiation directional surface pointing towards the lower-level machines or sensor clusters requiring centralized connection. Due to its directional radiation characteristics, the antenna effectively focuses radio frequency energy, reducing clutter interference from other directions and improving the link's signal-to-noise ratio. Its forward half-power beamwidth is very wide in the low-frequency band, approaching omnidirectional coverage, facilitating search and initial connection; in the high-frequency band, the beam is more concentrated with significant gain, dedicated to high-speed data backhaul. This dual-frequency directional characteristic allows a single gateway to connect a large number of devices via a wide-angle low-frequency band, and also to perform high-volume data exchange with key devices via a fixed-point high-frequency band. This perfectly aligns with the hierarchical communication architecture of the Industrial Internet of Things (IIoT), and the entire structure is implemented on a printed circuit board (PCB), ensuring high reliability and ease of mass production and integration.

[0043] Example 3: High-gain directional antenna module for wireless access points This embodiment provides a dual-band directional PCB antenna as an independent antenna module, mainly used in wireless access points in public areas such as shopping malls and airports to achieve long-distance and high-quality coverage in a specific direction. The core of this module is the printed circuit board 1, on which a pair of optimized planar inverted-F antennas (PIFAs) 2 are integrated. These two PIFAs are symmetrically arranged in a dipole configuration and are jointly connected to a large-area ground metal layer on the second layer of the printed circuit board 1. This symmetrical structure with a shared ground is key to forming a directional radiation pattern, ensuring that radiated energy is mainly concentrated in the direction indicated by the normal to the ground plane, while back radiation is very weak.

[0044] Each PIFA unit comprises a main radiating arm 3 and a branch radiating arm 7. The main radiating arm 3 is the core for achieving low-frequency coverage, and its physical length determines the resonant point of that frequency band. The branch radiating arm 7 is connected to the end of the main radiating arm 3. Through the design of its length and coupling relationship, it is specifically used to excite high-frequency resonance and, together with the current distribution of the main radiating arm 3, forms a composite radiation mode, improving high-frequency performance. At least two short-circuit posts 4 firmly connect the radiating arm to the ground plane, ensuring structural stability and electrical performance consistency. The signal is introduced through a microstrip feed line 5 and coupled to the radiator via the coupling slot 6 above it, achieving good impedance matching.

[0045] In practical deployments, this antenna module is typically used in array configuration. For example, four identical modules can be mounted on the four sides of an access point device, with each module's directional radiating surface facing a different coverage sector. This allows a single access point to achieve seamless 360-degree coverage, with each sector served by an independent directional antenna. Since each antenna module has higher gain in its pointing direction than an omnidirectional antenna, especially at higher frequencies, it effectively increases the coverage radius and edge field strength of a single access point. Simultaneously, its directional radiation characteristics help reduce co-channel interference between sectors, improving overall network capacity and user experience. This design is fully compatible with mainstream wireless network specifications and can be seamlessly integrated into multiple-input multiple-output (MIMO) systems, significantly improving wireless network performance in dense user environments.

[0046] Example 4: Stable transmission antenna for wireless video surveillance systems This embodiment describes the specific application of a dual-band directional PCB antenna in a wireless video surveillance system, focusing on solving the problem of stable and real-time transmission of video data streams. The antenna is constructed on a compact printed circuit board 1. A pair of planar inverted-F antennas PIFA 2 on the board adopt a symmetrical dipole layout and share a second overall ground metal layer, forming a radiator with a clear directionality. This directional radiation characteristic is crucial for surveillance applications, as it can concentrate signal energy towards the monitoring center or relay equipment, thereby obtaining stronger effective signal power and anti-interference capability.

[0047] The antenna's operating frequency band is jointly determined by the main radiating arm 3 and the branch radiating arm 7. The main radiating arm 3 generates a low-frequency resonance, which has strong penetration and can be used for reliable control signal transmission and video base stream transmission in non-line-of-sight or complex environments. The branch radiating arm 7 works in conjunction with the main radiating arm 3 to generate a high-frequency resonance. This frequency band has a large usable bandwidth and can support high bitrate transmission of high-definition or even ultra-high-definition video streams. At least two shorting posts 4 provide a low-inductance grounding path, and the microstrip feed line 5 and coupling slot 6 form an efficient feeding network, ensuring efficient energy conversion from the transceiver to the radiator.

[0048] When installing the antenna at the monitoring point, seal it in a waterproof housing and fix it near the camera or integrate it with the camera design. During installation, the antenna's orientation must be precisely adjusted to ensure its directional radiation surface is accurately aligned with the receiving base station. After adjustment, the antenna's wide beamwidth in the low-frequency band provides a certain degree of azimuth tolerance, ensuring uninterrupted link transmission; while in the high-frequency band, its narrower beamwidth and higher gain characteristics provide a stable, high-speed wireless channel for large-volume video streams. This dual-band collaborative mode ensures the reliability of control commands and basic video streams while meeting the speed requirements of high-quality video transmission, making it ideal for applications such as urban security, forest fire prevention, and construction site monitoring that require remote wireless video backhaul.

[0049] Example 5: Wireless Network Extension for Educational or Office Environments This embodiment describes an implementation of a dual-band directional PCB antenna for expanding wireless network coverage in educational or office environments. The antenna uses a printed circuit board 1 as its carrier and employs a standard FR-4 or higher performance substrate. A pair of symmetrical planar inverted-F antennas PIFA 2 are fabricated on the board, arranged in a dipole configuration and sharing a ground metal layer, thus inherently possessing the directional radiation capability to focus signals forward.

[0050] Each PIFA contains key components: the main radiating arm 3 is the main body for low-frequency radiation; the branch radiating arm 7 extends from the end of the main radiating arm 3 and is responsible for exciting high-frequency resonance; at least two shorting posts 4 provide robust grounding; and the microstrip feed line 5 and coupling slot 6 together complete signal feeding. The coupling between the branch radiating arm 7 and the main radiating arm 3 enables the formation of an effective composite radiation mode in the high-frequency band, improving the radiation efficiency of this band.

[0051] In specific network extension scenarios, such as covering a narrow corridor or an open lecture hall, the omnidirectional antennas of traditional wireless routers can lead to signal wastage in unwanted directions and insufficient strength in the desired extension directions. In such cases, a device integrating this antenna (such as a wireless repeater or access point) can be deployed at one end of the area. During installation, ensure that the plane of the antenna printed circuit board 1 is perpendicular to the long side of the long strip area to be covered, so that the maximum radiation direction of the directional beam generated by a pair of PIFAs 2 is along the long axis of the corridor or classroom. This allows the wide beam in the low-frequency band to uniformly cover the near and middle areas, while the narrow beam and high-gain characteristics of the high-frequency band can effectively project high-speed network signals to the far area, overcoming the attenuation caused by distance. In this way, a single device can efficiently extend the network in a specific direction, avoiding the complexity and cost of multi-point deployment, effectively solving the problems of signal blind spots and weak signals in local areas, and ensuring the continuity and high quality of wireless network access throughout the educational or office area.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A dual-band directional PCB antenna, characterized in that: a pair of planar inverted-F antennas (PIFA) (2) are arranged in a symmetrical structure on the printed circuit board (1), and the pair of PIFA are arranged in a dipole manner and share a ground metal layer arranged on the second layer of the printed circuit board (1) to form directional radiation; each PIFA comprises: a main radiation arm (3) arranged on the first layer of the printed circuit board, with a length of 22.5 mm, for generating a first-order resonance in the 2.4 GHz frequency band; at least two shorting posts (4) with a diameter of about 0.3 mm, vertically penetrating the printed circuit board, for electrically connecting one end of the main radiation arm to the ground metal layer; a microstrip feed line (5) arranged on the first layer, with a characteristic impedance of 50 ohms; a coupling slot (6) arranged on the ground metal layer directly above the microstrip feed line, with a length of 15 mm and a width of 0.25 mm, for realizing electromagnetic coupling between the microstrip feed line and the main radiation arm; a branch radiation arm (7) arranged at the end of the main radiation arm, with a length of 5.7 mm, for providing resonance in the 5 GHz frequency band.

2. A dual-band directional PCB antenna according to claim 1, characterized in that: The overall size of the printed circuit board (1) is 50 mm x 35 mm.

3. A dual-band directional PCB antenna according to claim 1, characterized in that: The arrangement of the pair of PIFA (2) makes the antenna have a gain of 2-3 dBi in the 2.4 GHz frequency band and a gain of 5-7 dBi in the 5 GHz frequency band.

4. A dual-band directional PCB antenna according to claim 1, characterized in that: The input standing wave ratio of the antenna in the 2.4 GHz and 5 GHz frequency bands is not greater than 2.

5. A dual-band directional PCB antenna according to claim 1, characterized in that: The printed circuit board (1) uses a substrate with a dielectric constant ε≈3.0 and a loss tangent tanδ≤0.0031.

6. A dual-band directional PCB antenna according to claim 1, characterized in that: The branch radiation arm (7) is coupled with the main radiation arm (3) in the same direction, forming a λ / 2 composite mode in the 5 GHz frequency band.

7. A dual-band directional PCB antenna according to claim 1, characterized in that: The at least two shorting posts (4) are a double via parallel structure, for reducing local inductance.

8. A dual-band directional PCB antenna according to claim 1, characterized in that: The forward half-power beamwidth of the pair of PIFA is 350°-360° in the 2.4 GHz frequency band and 120°-160° in the 5 GHz frequency band.

9. A dual-band directional PCB antenna according to claim 1, characterized in that: The width of the microstrip feed line (5) is 0.25 mm.

10. The dual-band directional PCB antenna according to claim 1, characterized in that: The antenna design conforms to the IEEE 802.11b / g / n / ac / ax specification and can be used in combination with a 2x2 or 4x4 MIMO router.

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