Planar end-on-fire antenna suitable for 915MHz and 2.45 GHz dual-frequency communication

Abstract

The utility model relates to a planar end-on-fire antenna suitable for 915MHz and 2.45 GHz dual-frequency communication, and belongs to the field of wireless communication antennas. The antenna comprises a director unit, an active oscillator unit, a coaxial feed line, a reflector unit and a dielectric substrate. The upper surface of the dielectric substrate is provided with a left radiator and a coaxial feeder in the active oscillator unit; a right radiator, a coaxial feeder, a reflector unit and a director unit in the active oscillator unit are arranged on the lower surface of the dielectric substrate; the coaxial feeder line is located in the middle of the dielectric substrate, the active oscillator unit is bilaterally symmetrical about the coaxial feeder line, and the coaxial feeder line is connected with the left radiator and the right radiator respectively; the upper end and the lower end of the coaxial feeder are respectively connected with the active oscillator unit and the reflector unit; the two ends of the reflector unit are provided with reflector folding parasitic units. The adjustable performance of structural parameters of the antenna supports customization of radiation patterns and frequency characteristics according to specific application scenes.

Description

Technical Field

[0001] This utility model relates to a planar end-fire antenna suitable for dual-band communication of 915MHz and 2.45GHz, belonging to the field of wireless communication antenna technology. Background Technology

[0002] Against the backdrop of rapid development in wireless communication technology, planar end-fire antennas, due to their compact structure and ease of integration, are widely used in the Internet of Things (IoT), Radio Frequency Identification (RFID), and short-range wireless sensing. However, with the increasing complexity of application scenarios, traditional planar end-fire antennas have gradually exposed various technical bottlenecks. Early planar end-fire designs focused primarily on single-band optimization, such as antenna structures for the 2.4GHz band, which achieved narrowband resonance by adjusting the dipole length or adding matching circuits. However, such designs struggle to meet the multi-band compatibility requirements of modern wireless devices. Taking warehousing and logistics scenarios as an example, RFID systems need to simultaneously support low-frequency (around 900MHz) tag identification and high-frequency (2.4GHz) data transmission. Traditional single-frequency antennas require additional independent antenna elements or complex filtering networks, leading to increased device size and cost.

[0003] Furthermore, the physical size limitation of antennas is a key obstacle to the integration of miniaturized devices. Traditional planar end-fire antennas typically require a lateral dimension greater than half the operating wavelength to achieve end-fire radiation characteristics. Taking the 915MHz band as an example, its free-space wavelength is approximately 328mm, meaning that the lateral dimension of traditional structures needs to exceed 160mm, severely restricting their deployment in handheld terminals or small sensors. Although some researchers have attempted to reduce size by bending dipoles or introducing parasitic elements, these solutions often come at the cost of bandwidth or radiation efficiency.

[0004] Another prominent issue is the insufficient directivity of antenna radiation. In industrial environments or dense shelving scenarios, multipath reflections and electromagnetic interference can significantly reduce communication reliability. The front-to-back ratio (FBR) of traditional planar end-fire antennas is generally below 10 dB, causing signal energy to leak in non-target directions. Although back radiation can be partially suppressed by adding a reflector to the radiating end, such improvements often increase structural complexity and negatively impact the radiation pattern in the high-frequency band, leading to an imbalance in dual-band performance.

[0005] These technical shortcomings collectively point to a core challenge: how to achieve efficient dual-band radiation within a limited space while maintaining low cost, high reliability, and strong environmental adaptability. Existing solutions often achieve breakthroughs in a single metric but struggle to achieve coordinated optimization across multiple objectives. This has become a key obstacle restricting the application of planar end-fire antennas in a wider range of scenarios. Summary of the Invention

[0006] The technical problem to be solved by this utility model is: This utility model provides a planar end-fire antenna suitable for dual-band communication of 915MHz and 2.45GHz, so as to solve the problems of traditional planar end-fire antennas focusing on a single frequency band, large physical size, and insufficient radiation directivity; This utility model realizes dual-band operation of 915MHz (UHF) and 2.45GHz (ISM), and supports parallel processing of RFID tag reading and writing and ISM transmission respectively.

[0007] The present invention provides a planar end-fire antenna suitable for dual-band communication of 915MHz and 2.45GHz, comprising a director unit 1, an active dipole unit 2, a coaxial feed line 3, a reflector unit 4, and a dielectric substrate 5.

[0008] The upper surface of the dielectric substrate 5 is provided with the left radiator and coaxial feed line 3 of the active oscillator unit 2;

[0009] The right radiator, coaxial feed line 3, reflector unit 4 and director unit 1 of the active oscillator unit 2 are disposed on the lower surface of the dielectric substrate 5.

[0010] The coaxial feed line 3 is respectively disposed on the upper and lower surfaces of the dielectric substrate 5 and is located in the middle of the dielectric substrate 5. The active oscillator unit 2 is symmetrical about the coaxial feed line 3. The coaxial feed line 3 is connected to the left radiator and the right radiator respectively.

[0011] The left and right radiators in the active oscillator unit 2 are folded structures. The upper and lower ends of the coaxial feed line 3 are connected to the active oscillator unit 2 and the reflector unit 4, respectively. The reflector unit 4 is provided with reflector folded parasitic units at both ends.

[0012] As a further embodiment of this utility model, the left radiator and the right radiator in the active oscillator unit 2 have the same structure; the left and right radiators in the active oscillator unit 2 are symmetrical about the coaxial feed line 3.

[0013] Among them, the left and right radiators of the active oscillator unit 2 have a folded structure with a peak length of 12mm, a peak height of 14mm, and a width of 4mm.

[0014] The distance between the active oscillator unit 2 and the director unit 1 is 6mm.

[0015] As a further embodiment of this invention, the length of the active oscillator unit 2 is greater than the length of the director unit 1 and equal to the length of the reflector unit 4.

[0016] As a further embodiment of this utility model, the dielectric substrate 5 is made of FR4 material with a dielectric constant of 4.4 and a loss tangent of 0.02.

[0017] As a further embodiment of this invention, the active oscillator unit 2 adopts a radiating body folded dipole structure.

[0018] As a further embodiment of this utility model, the director unit 1, the active oscillator unit 2, and the reflector unit 4 are all made of copper.

[0019] As a further embodiment of this utility model, the dimensions and lengths of the director unit 1, the active oscillator unit 2, and the reflector unit 4 are 36mm, 45mm, and 87.2mm, respectively.

[0020] The active oscillator unit of this invention adopts a folded dipole structure with symmetrical distribution on the upper and lower surfaces, and achieves impedance matching through coaxial feed lines, effectively expanding the operating bandwidth.

[0021] By optimizing the element spacing and structural parameters, the antenna achieves dual-band coverage of 915MHz and 2.45GHz, which can simultaneously meet the requirements of mainstream wireless communication standards such as the Internet of Things (IoT) and Wi-Fi.

[0022] The experimental results show that while maintaining the advantages of a typical planar end-fire antenna, the transverse dimension of this antenna has been effectively reduced compared to traditional designs, and it exhibits good directivity and stable radiation characteristics in both operating frequency bands.

[0023] Thanks to its modular design, this antenna is not only fully compatible with existing planar antenna manufacturing processes, significantly reducing production costs, but its adjustable structural parameters also allow for customization of radiation patterns and frequency characteristics according to specific application scenarios. It can be widely used in wireless communication systems that require directional radiation and dual-frequency operation, such as smart warehousing and industrial IoT.

[0024] This invention relates to a planar end-fire antenna for dual-band communication. The antenna features dual-band performance, covering the 915MHz and 2.45GHz frequency bands respectively. Furthermore, it possesses excellent unidirectional radiation characteristics. To extend the operating bandwidth, a folded dipole technique is incorporated into the design. Simultaneously, through optimized design, the antenna's lateral dimensions are effectively reduced. This antenna can operate independently on two different frequency bands. This flexibility and adaptability give it significant advantages in dual-band operation applications.

[0025] The beneficial effects of this utility model are:

[0026] 1. The active oscillator unit of this utility model adopts a folded dipole structure with symmetrical distribution on the upper and lower surfaces, and achieves impedance matching through coaxial feed lines, which effectively expands the working bandwidth.

[0027] 2. By optimizing the unit spacing and structural parameters, this utility model enables the antenna to achieve dual-band coverage of 915MHz and 2.45GHz, which can simultaneously meet the requirements of mainstream wireless communication standards such as the Internet of Things (IoT) and Wi-Fi.

[0028] The antenna provided by this utility model is particularly suitable for dual-band RFID handheld readers due to its excellent performance and flexibility; at the same time, the adjustment flexibility of the antenna of this utility model enables it to adapt to other specific wireless application scenarios with directional radiation and dual-band operation.

[0029] 3. The test results show that while maintaining the advantages of a typical planar end-fire antenna, the transverse dimension of this novel antenna is effectively reduced compared to traditional designs, and it exhibits good directivity and stable radiation characteristics in both operating frequency bands.

[0030] 4. Thanks to the modular design concept, the antenna of this utility model is not only fully compatible with the existing planar antenna manufacturing process, significantly reducing production costs, but its structural parameters are also adjustable, allowing for customization of radiation pattern and frequency characteristics according to specific application scenarios. It can be widely used in wireless communication systems that require directional radiation and dual-frequency operation, such as smart warehousing and industrial IoT. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the planar end-fire antenna for dual-frequency communication according to Embodiment 1 of this utility model. Figure 1 ;

[0032] Figure 2 This is a schematic diagram of the planar end-fire antenna for dual-frequency communication according to Embodiment 1 of this utility model. Figure 2 To better distinguish the components on the upper and lower surfaces of the dielectric substrate 5, [details omitted]. Figure 2 The gray part is the component provided on the upper surface of the dielectric substrate 5, and the black part is the component provided on the lower surface of the dielectric substrate 5.

[0033] Figure 3 The diagram shows the S11 and front-to-back ratio parameters of the antenna of this utility model.

[0034] Figure 4 The radiation pattern of the planar end-fire antenna for dual-frequency communication in Embodiment 1 of this utility model is shown in the E-plane at 915MHz.

[0035] Figure 5 The radiation pattern of the planar end-fire antenna for dual-frequency communication in Embodiment 1 of this utility model is shown in the H-plane at 915MHz.

[0036] Figure 6 The radiation pattern of the planar end-fire antenna for dual-frequency communication in Embodiment 1 of this utility model is shown in the E-plane at 2.45 GHz.

[0037] Figure 7 The radiation pattern of the planar end-fire antenna for dual-frequency communication in Embodiment 1 of this utility model is shown in the H-plane at 2.45 GHz.

[0038] The reference numerals are as follows: 1-Director unit, 2-Active oscillator unit, 3-Coaxial feed line, 4-Reflector unit, 5-Dielectric substrate. Detailed Implementation

[0039] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0040] It should be noted that if the embodiments of this utility model involve directional indicators such as up, down, left, right, front, and back, the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture as shown in the attached figure. If the specific posture changes, the directional indicators will also change accordingly.

[0041] Example 1: Please refer to Figures 1 to 7 Embodiment 1 of this utility model is as follows: Figure 1 As shown, a planar end-fire antenna suitable for dual-band communication in 915MHz (UHF band) and 2.45GHz (ISM) is presented. The antenna employs a multi-layer composite structure design, mainly including a director element 1, an active dipole element 2, a coaxial feed line 3, a reflector element 4, and a dielectric substrate 5. The active dipole element adopts a folded dipole structure symmetrically distributed on its upper and lower surfaces, and impedance matching is achieved through the coaxial feed line, effectively extending the operating bandwidth. By optimizing the element spacing and structural parameters, the antenna achieves dual-band coverage in both 915MHz and 2.45GHz bands, simultaneously meeting the requirements of mainstream wireless communication standards such as the Internet of Things (IoT) and Wi-Fi. Specifically:

[0042] The upper surface of the dielectric substrate 5 is provided with the left radiator and coaxial feed line 3 of the active oscillator unit 2; the lower surface of the dielectric substrate 5 is provided with the right radiator, coaxial feed line 3, reflector unit 4, and director unit 1 of the active oscillator unit 2; the coaxial feed line 3 is respectively provided on the upper and lower surfaces of the dielectric substrate 5 and is located in the middle of the dielectric substrate 5; the active oscillator unit 2 is symmetrical about the coaxial feed line 3, and the coaxial feed line 3 is connected to the left and right radiators respectively; the left and right radiators of the active oscillator unit 2 are folded structures (folded structure refers to transforming the traditional straight dipole into a multi-segment bent conductor path, thereby increasing the effective current path length and reducing the resonant frequency in a limited space (vertical L-shaped bend, 90° right-angle transition region)); the upper and lower ends of the coaxial feed line 3 are connected to the active oscillator unit 2 and the reflector unit 4 respectively; the two ends of the reflector unit 4 are provided with reflector folded parasitic units. The coaxial feed line 3 supplies power to the active oscillator unit 2 and adjusts the impedance matching; the material is copper.

[0043] The coaxial feed line 3 on the dielectric substrate 5 is combined with the left radiator of the active oscillator unit 2. The combination of the reflector unit 4 under the dielectric substrate 5 with the coaxial feed line 3, and the combination of the coaxial feed line 3 with the right radiator of the active oscillator unit 2, allows the radiator folded dipole structure adopted by the active oscillator unit 2 to emit an electromagnetic field and form directional radiation.

[0044] As a further embodiment of this utility model, the left radiator and the right radiator in the active oscillator unit 2 have the same structure; the left and right radiators in the active oscillator unit 2 are symmetrical about the coaxial feed line 3.

[0045] Among them, the left and right radiators of the active oscillator unit 2 have a folded structure with a peak length of 12mm, a peak height of 14mm, and a width of 4mm.

[0046] The distance between the active oscillator unit 2 and the director unit 1 is 6mm.

[0047] As a further embodiment of this invention, the length of the active oscillator unit 2 is greater than the length of the director unit 1 and equal to the length of the reflector unit 4.

[0048] As a further embodiment of this utility model, the dielectric substrate 5 is made of FR4 material with a dielectric constant of 4.4 and a loss tangent of 0.02.

[0049] As a further embodiment of this invention, the active oscillator unit 2 adopts a radiating body folded dipole structure.

[0050] As a further embodiment of this utility model, the director unit 1, the active oscillator unit 2, and the reflector unit 4 are all made of copper.

[0051] As a further embodiment of this utility model, the dimensions and lengths of the director unit 1, the active oscillator unit 2, and the reflector unit 4 are 36mm, 45mm, and 87.2mm, respectively.

[0052] The working principle of this utility model includes:

[0053] This invention relates to a planar end-fire antenna suitable for dual-band communication of 915MHz (UHF band) and 2.45GHz (ISM).

[0054] Low frequency band (915MHz): A closed current path is formed by reflector unit 4 (using Moxon reflector) and active oscillator unit 2 (using radiator folded dipole) to excite UHF band resonance;

[0055] High-frequency band (2.45GHz): Traveling wave radiation is formed by the Yagi director array and the same folded dipole drive unit to realize directional beam in the ISM band.

[0056] 1. For director unit 1;

[0057] Structural features: Located on the top layer of the dielectric substrate, arranged in front of the active oscillator unit 2 (in the main electromagnetic radiation direction); the length is optimized to 36mm (approximately 0.3 times the 2.45GHz wavelength), and the distance between it and the active oscillator unit 2 is fixed at 6mm (approximately 0.05 times the 2.45GHz wavelength).

[0058] Functions and working principle:

[0059] High-frequency selective coupling:

[0060] In the 2.45GHz band, the electrical length of director unit 1 is close to half a wavelength, and it undergoes strong electromagnetic coupling with the high-frequency current of active oscillator unit 2, guiding electromagnetic waves to radiate directionally towards the front end (+z direction);

[0061] By shortening the length of director unit 1 (approximately 0.4-0.5λ for conventional Yagi directors), high-frequency radiation efficiency is improved.

[0062] Low-frequency isolation:

[0063] In the 915MHz band, the electrical length of director unit 1 is only 0.12λ, which is far below the half-wavelength resonance requirement. It exhibits high impedance characteristics and hardly participates in low-frequency radiation, thus avoiding frequency band interference.

[0064] 2. For active oscillator element 2;

[0065] Structural features:

[0066] Folded dipole design, including left / right symmetrical radiators:

[0067] Top layer: Drive arm (length L1 = 45mm);

[0068] Bottom layer: Feeder arm (length L2 = 45mm);

[0069] Folding height h = 10mm.

[0070] Functions and working principle:

[0071] Dual-frequency resonant excitation:

[0072] Low-frequency path (915MHz): Current flows along the entire length (L1+L2+h) of the folded structure, forming an equivalent λ / 4 resonant circuit, which excites 915MHz radiation.

[0073] High-frequency path (2.45GHz): Current is concentrated at the folding and bending nodes, with an equivalent electrical length of ≈λ / 4, which excites a 2.45GHz resonance.

[0074] Balanced power supply support:

[0075] The double-sided printed structure forces a symmetrical current distribution, suppresses common-mode interference, and ensures the directivity of the terminal emission.

[0076] 3. For coaxial feeder 3;

[0077] Structural features: The inner conductor connects to the top-level drive arm, and the outer conductor connects to the bottom-level feed arm and reflector unit 4; the feed line width wf = 2.8mm (characteristic impedance 50Ω);

[0078] Functions and working principle:

[0079] Dual-frequency energy transfer: Balanced current is injected into the active oscillator through a parallel microstrip line structure to avoid pattern distortion.

[0080] Impedance matching hub: Optimizes WF width to match dual-frequency input impedance.

[0081] 4. For reflector unit 4;

[0082] Structural features: Moxon type design, located on the bottom layer of the dielectric substrate, with a distance of d1 = 14mm (0.04λ) between it and the active oscillator unit 2; end branch length L4 = 28mm;

[0083] Functions and working principle:

[0084] Dual-frequency phase reversal:

[0085] Low frequency: 14mm spacing enables near-field coupling, reflection phase is reversed 180°, and forward gain is enhanced;

[0086] High frequency: The arc-shaped structure extends the reflection phase bandwidth, maintaining a 180° phase difference with a spacing of 0.11λ;

[0087] Posterior lobe suppression:

[0088] Back radiation is suppressed by phase cancellation.

[0089] The present invention supports RFID tag reading and writing functions through the 915MHz (UHF) frequency band reading and writing function.

[0090] 1. The hardware foundation for ISM transport parallel processing includes:

[0091] This utility model presents a composite antenna structure for planar end-fired dual-band communication (915MHz and 2.45GHz) to achieve physical isolation between the two bands.

[0092] Low-frequency RFID channel: independently controlled by a Moxon structure (folded dipole + reflector), resonating at 915MHz;

[0093] High-frequency ISM channel: dominated by Yagi directors, resonating at 2.45GHz (current concentrated in the directors);

[0094] 2. Dual-frequency isolation mechanism;

[0095] (1) Frequency domain isolation;

[0096] Shared reflector design:

[0097] Yagi reflectors suppress 2.45GHz resonance, so Moxon reflectors are used to balance dual-frequency operation.

[0098] (2) Spatial isolation;

[0099] End-fire beam directivity ( Figure 4 , 5 6, 7):

[0100] 915MHz beam half-power angle: E-plane ±32° / H-plane ±35° (vertical coverage of tag clusters);

[0101] 2.45GHz beam half-power angle: E-plane ±28° / H-plane ±30° (ISM equipment horizontal pointing).

[0102] To illustrate the advantages of this utility model as a planar end-fire antenna suitable for dual-band communication of 915MHz (UHF band) and 2.45GHz (ISM), this utility model controlled variables and conducted gain experiments.

[0103] Experimental group (practical planar end-fire antenna suitable for dual-band communication of 915MHz (UHF band) and 2.45GHz (ISM): structure as follows Figure 1 As shown.

[0104] Figure 3This is a diagram showing the S11 and front-to-back ratio parameters of the antenna of this utility model. Figure 3 It can be seen that the antenna's -10dB impedance bandwidth at low frequency (915MHz) is 28.4% (0.86-1.12GHz), the 15dB front-to-back ratio bandwidth is 12% (0.89-1GHz), and the maximum front-to-back ratio is 34.5dB; the antenna's -10dB impedance bandwidth at high frequency (2.45GHz) is 16.3% (2.31-2.71GHz), the 15dB front-to-back ratio bandwidth is 13.1% (2.33-2.65GHz), and the maximum front-to-back ratio is 23.8dB. These results indicate that the planar end-fire antenna for dual-frequency communication has certain advantages in both high and low frequency bands, making it more suitable for dual-frequency operation.

[0105] Figure 4 and Figure 5 The normalized radiation patterns of the planar end-fire antenna for dual-band communication in Embodiment 1 of this utility model are shown in the E-plane and H-plane at a frequency of 915MHz. The simulated gain of this dual-band antenna reaches 5.2dBi. Figures 4-5 As can be seen from this, the antenna of this utility model has excellent radiation characteristics. Figure 6 and Figure 7 The planar end-fire antenna for dual-band communication in Embodiment 1 of this utility model achieved a simulated gain of 5.3 dBi at 2.45 GHz. Figures 6-7 As can be seen, the antenna of this invention possesses excellent radiation characteristics. In the E-plane and H-plane at different frequencies, the antenna performs particularly well in terms of cross-horizontal polarization.

[0106] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A planar end-fire antenna suitable for dual-band communication of 915MHz and 2.45GHz, characterized in that: It includes a director unit (1), an active oscillator unit (2), a coaxial feed line (3), a reflector unit (4), and a dielectric substrate (5); The upper surface of the dielectric substrate (5) is provided with the left radiator and coaxial feed line (3) of the active oscillator unit (2); The right radiator, coaxial feed line (3), reflector unit (4) and director unit (1) of the active oscillator unit (2) are disposed on the lower surface of the dielectric substrate (5); The coaxial feed line (3) is respectively disposed on the upper and lower surfaces of the dielectric substrate (5) and located in the middle of the dielectric substrate (5). The active oscillator unit (2) is symmetrical about the coaxial feed line (3) and the coaxial feed line (3) is connected to the left radiator and the right radiator respectively. The left and right radiators in the active oscillator unit (2) are folded structures. The upper and lower ends of the coaxial feed line (3) are connected to the active oscillator unit (2) and the reflector unit (4) respectively. The reflector unit (4) is provided with reflector folded parasitic units at both ends.

2. The planar end-fire antenna suitable for dual-band communication of 915MHz and 2.45GHz according to claim 1, characterized in that: The left radiator and the right radiator in the active oscillator unit (2) have the same structure; the left radiator and the right radiator in the active oscillator unit (2) are symmetrical about the coaxial feed line (3); Among them, the left and right radiators of the active oscillator unit (2) have a peak length of 12mm, a peak height of 14mm, and a width of 4mm. The distance between the active oscillator unit (2) and the director unit (1) is 6 mm.

3. The planar end-fire antenna suitable for dual-band communication of 915MHz and 2.45GHz according to claim 1, characterized in that: The length of the active oscillator unit (2) is greater than the length of the director unit (1) and equal to the length of the reflector unit (4).

4. The planar end-fire antenna suitable for dual-band communication of 915MHz and 2.45GHz according to claim 1, characterized in that: The dielectric substrate (5) is made of FR4 material with a dielectric constant of 4.4 and a loss tangent of 0.

02.

5. A planar end-fire antenna suitable for dual-band communication of 915MHz and 2.45GHz according to claim 1, characterized in that: The active oscillator unit (2) adopts a radiator folded dipole structure.

6. The planar end-fire antenna suitable for dual-band communication of 915MHz and 2.45GHz according to claim 1, characterized in that: The director unit (1), the active oscillator unit (2), and the reflector unit (4) are all made of copper.

7. A planar end-fire antenna suitable for dual-band communication of 915MHz and 2.45GHz according to claim 1, characterized in that: The dimensions of the director unit (1), the active oscillator unit (2), and the reflector unit (4) are 36mm, 45mm, and 87.2mm, respectively.

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