Miniaturized multi-channel power divider applied to low frequency band

Abstract

The invention discloses a miniaturized multi-channel power divider applied to a low frequency band, which comprises a total port matching transmission line, at least two groups of sub-port matching transmission lines and corresponding sub-port isolation networks, and is characterized in that the total port matching transmission line is connected with each sub-port matching transmission line through a microstrip transmission line and a T-shaped transmission line; the tail ends of the branch port matching transmission lines are connected with the branch port isolation networks, the tail ends of all the branch port isolation networks are communicated with one another, and the working frequency range is 32.5 MHz to 37.5 MHz. The lumped elements and the microstrip lines are matched to optimize the impedance characteristic, the size is only 1 / 10 of that of a conventional power divider, and the problem that the size of a low-frequency-band power divider is too large is solved; and meanwhile, the multi-path power divider has low insertion loss, high port isolation and good phase consistency, can realize multi-path power distribution by adjusting the number of branches, is adaptive to the compact radio frequency module requirements of portable and embedded equipment, and is suitable for scenes such as private network communication, Internet of Things, aviation communication and the like.

Description

Technical Field

[0001] This invention belongs to the field of microwave communication technology, and particularly relates to a miniaturized power divider for use in the low-frequency band. Background Technology

[0002] Power dividers are key passive components in radio frequency (RF) and microwave circuits and systems. Their core function is to distribute a single input signal into multiple output signals according to specific amplitude and phase relationships, or conversely, to combine multiple signals into a single output. They play an irreplaceable role in wireless communication, radar, satellite navigation, and test and measurement. With the development of modern wireless communication systems (such as private network communication, IoT, VHF / UHF band broadcasting, and aviation communication) towards lower frequency bands (e.g., 30-100MHz), there are increasing demands for miniaturization, high integration, and low cost for RF front-end modules operating in this band. This design aims to develop a miniaturized microstrip power divider for use at center frequencies below 1GHz. The core objective is to achieve significant size reduction while maintaining good electrical performance (including low insertion loss, high port isolation, and good input / output return loss), enabling it to be integrated into compact RF modules.

[0003] The physical length of traditional microstrip or stripline power dividers is proportional to their operating wavelength. In the frequency band below 1 GHz, especially around 30 MHz, the free-space wavelength is approximately 10 meters. Even on dielectric substrates with high dielectric constants, the guided wave wavelength of microstrip lines is typically in the meter range. This directly results in traditional power dividers based on quarter-wavelength transmission lines being excessively large (often exceeding tens or even hundreds of centimeters), making it difficult to meet the stringent board space requirements of modern portable and embedded devices.

[0004] To reduce size, conventional methods include using high-dielectric-constant substrates, loading lumped elements (inductors, capacitors), or employing folded or bent slow-wave structures. However, these methods often introduce new problems in the low-frequency range: High dielectric constant substrates: Higher cost and may increase transmission loss.

[0005] Lumped component loading: In the low-frequency range, the required inductance and capacitance values ​​are often large, resulting in significant component size, and the parasitic effects and power capacity of discrete components may become limiting factors.

[0006] Strong coupling and radiation loss: When the circuit size is compressed to be much smaller than the wavelength, the electromagnetic coupling between different parts of the circuit is intensified, which may cause additional radiation loss and deterioration of port isolation. Summary of the Invention

[0007] To address the problems in the prior art, the present invention proposes the following technical solution: A miniaturized power divider for low-frequency applications includes a main port matching transmission line, at least two sets of sub-port matching transmission lines, and sub-port isolation networks corresponding to each sub-port matching transmission line. The main port matching transmission line is connected to each sub-port matching transmission line via microstrip transmission lines and T-type transmission lines. The ends of each sub-port matching transmission line are connected to the corresponding sub-port isolation network, and the ends of all sub-port isolation networks are interconnected. The power divider operates in the frequency band of 32.5MHz to 37.5MHz.

[0008] As a preferred embodiment of the above technical solution, the total port matching transmission line includes Port1 total port excitation, two impedance matching transmission lines, and a grounding capacitor C5; the width of the two impedance matching transmission lines is w0, and the spacing is P=10mm. The grounding capacitor C5 works with the two impedance matching transmission lines to achieve total port impedance matching.

[0009] As a preferred embodiment of the above technical solution, the port matching transmission line includes a port, two impedance matching transmission lines, an inductor L1, and a grounding capacitor C1; the width of the two impedance matching transmission lines is w1, and the spacing is P=5mm. The inductor L1 and the grounding capacitor C1 work together to achieve impedance matching between the port and the total transmission path.

[0010] As a preferred embodiment of the above technical solution, the port isolation network includes four impedance matching transmission lines, an inductor L4, a grounding capacitor C4, and an isolation resistor R1; the width of each of the four impedance matching transmission lines is w2, wherein the spacing between two sets of transmission lines is P=5mm, and the spacing between the other two sets of transmission lines is P=28mm, and the size relationship of 2w=W is satisfied. The end of the isolation resistor R1 is interconnected with the ends of the isolation resistors of other port isolation networks.

[0011] As a preferred embodiment of the above technical solution, w0=2mm in the main port matching transmission line and the grounding capacitor C5=10pF; w1=1.5mm in the sub-port matching transmission line, the inductance L1=10μH and the grounding capacitor C1=15pF.

[0012] As a preferred embodiment of the above technical solution, in the port isolation network, w2=1mm, W=2mm, the inductor L4=8μH, the grounding capacitor C4=12pF, and the isolation resistor R1=50Ω.

[0013] As a preferred embodiment of the above technical solution, the microstrip transmission line and the T-type transmission line are made of copper; the dielectric substrate of the power divider is made of FR-4 material, the dielectric constant of the dielectric substrate is εr=4.4, and the thickness is h=1.6mm; the volume of the power divider is 1 / 10 of the volume of a conventional power divider in the same frequency band.

[0014] A miniaturized multi-channel power distribution method for low-frequency applications, based on the aforementioned power divider, includes the following steps: Step 1: The input signal is excited through Port1 and enters the main port matching transmission line. Impedance optimization is completed through the cooperation of two sections of impedance matching transmission line and grounding capacitor C5. Step 2: The optimized signal is evenly distributed to each port matching transmission line via microstrip transmission line and T-type transmission line; Step 3: The signal transmission characteristics are stabilized through the combined action of inductor L1, grounding capacitor C1 and two impedance matching transmission lines at each port. Step 4: The port isolation network suppresses signal interference between ports through the impedance adjustment of four impedance transmission lines, inductor L4, grounding capacitor C4, and the interconnection of isolation resistor R1, ultimately achieving uniform distribution of one input signal to multiple output signals.

[0015] The beneficial effects of this invention are as follows: 1. Achieving extreme miniaturization and low-cost design, by using a lumped component (inductor, capacitor) and microstrip line synergistic impedance matching scheme, it breaks through the size limitations of traditional power dividers that rely on wavelength-dependent transmission lines. The product volume is only 1 / 10 of that of conventional power dividers in the same frequency band, adapting to the installation requirements of compact RF modules; at the same time, it does not require the use of high dielectric constant substrates, but uses conventional FR-4 dielectric substrates and copper transmission lines, reducing production costs while reducing the impact of parasitic effects and improving operational reliability. 2. It combines excellent electrical performance with flexible scalability, achieving low insertion loss (≤3.5dB), high port isolation (≥20dB), and good return loss (absolute value ≥15dB) in the low frequency band of 32.5MHz~37.5MHz. The phase difference between each sub-port is ≤5°, ensuring stable signal transmission with minimal interference. By adjusting the number of matching transmission lines and isolation networks at each sub-port, power distribution can be flexibly achieved in any configuration greater than 2 channels, such as 1 to 4 or 1 to 6, adapting to the needs of various scenarios such as private network communication, IoT, and aviation communication. Attached Figure Description

[0016] Figure 1 : Schematic diagram of the overall structure of the 1-to-6 power divider of this invention; Figure 2 : Schematic diagram of the overall port matching transmission line structure; Figure 3 : Schematic diagram of port-matched transmission line structure; Figure 4 : Diagram of a port-isolated network structure; Figure 5 : Return loss test curves for each port; Figure 6Insertion loss test curves for each port; Figure 7 Phase consistency test curves for each port; Figure 8 : Port isolation test curve; Figure 9 Product external dimensions diagram.

[0017] The markings in the attached diagram are explained as follows: Port1 - Main port excitation, Port2 - Sub-port, w0 - Main port matching transmission line width, w1 - Sub-port matching transmission line width, w2 - Isolation network transmission line width, P - Transmission line spacing, C1, C4, C5 - Grounding capacitors, L1, L4 - Inductors, R1 - Isolation resistor. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0019] To address the shortcomings of existing low-frequency power dividers, such as excessive size and performance degradation during miniaturization, the present invention aims to provide a miniaturized multi-channel power divider applicable to the low-frequency band below 1 GHz. While ensuring low insertion loss, high port isolation, and good input / output return loss, it achieves significant size reduction and supports multi-channel signal distribution, thus meeting the needs of compact RF modules.

[0020] II. Technical Solution This invention is based on the Kinsell 1-to-2 power divider structure and combines it with stepped impedance matching theory. Through the design of lumped elements and microstrip lines, it achieves effective power distribution across multiple channels in the low-frequency band. The specific technical solution is as follows: (a) Product Composition Taking a 1-to-6 power divider as an example, this product consists of three core parts: a main port matching transmission line, a branch port matching transmission line, and a branch port isolation network. Each part is interconnected through microstrip transmission lines and T-type transmission lines to form a complete multi-channel power divider structure.

[0021] (II) Technical Features of Each Part The total port matching transmission line consists of Port1 (total port excitation), two impedance matching transmission lines, and a grounding capacitor C5. The width of the two impedance matching transmission lines is w0, and the spacing is P=10mm. The grounding capacitor C5 is used to optimize the impedance matching characteristics of the total port and ensure stable transmission of the input signal.

[0022] Port matching transmission line: Each port corresponds to a set of matching transmission lines, which consists of the port, two impedance matching transmission lines, inductor L1 and grounding capacitor C1. The width of the two impedance matching transmission lines is w1 and the spacing is P=5mm. Inductor L1 and grounding capacitor C1 work together to achieve impedance matching between the port and the total transmission path.

[0023] The port isolation network consists of four impedance matching transmission lines, an inductor L4, a grounding capacitor C4, and an isolation resistor R1. The width of each of the four impedance matching transmission lines is w2. The spacing between two sets of transmission lines is P=5mm, and the spacing between the other two sets is P=28mm, satisfying the dimensional relationship 2w=W. The ends of the isolation resistor R1 are interconnected to improve the isolation performance between the ports.

[0024] (III) Connections between the parts The main port matching transmission line connects to each sub-port matching transmission line via a microstrip transmission line and a T-type transmission line. The end of each sub-port matching transmission line is directly connected to the sub-port isolation network. The ends of the isolation resistors R1 of all sub-port isolation networks are interconnected, forming a complete isolation loop.

[0025] (iv) Work process The multi-channel power divider of this invention can achieve power distribution of any number of channels greater than two by adjusting the number of channels. Taking a one-to-six split as an example: the input signal enters the main port matching transmission line through the main port Port1. After impedance matching optimization, it is evenly distributed to the six branch port matching transmission lines through the T-shaped transmission line. The signal transmission characteristics of each branch port matching transmission line are ensured by the synergistic effect of inductor L1, grounding capacitor C1 and impedance transmission line. The branch port isolation network suppresses signal interference between branches through the impedance adjustment of four segments of impedance transmission line, inductor L4, grounding capacitor C4 and the interconnection of isolation resistor R1. Finally, it achieves the even distribution of one input signal to six output signals, and each output signal maintains good phase consistency and isolation.

[0026] Example 1: One-to-six power divider (a) Structural parameters Total port matching transmission line: two impedance matching transmission line segments with width w0=2mm, spacing P=10mm, and grounding capacitance C5=10pF; The impedance matching transmission line consists of two segments: a width w1 = 1.5 mm, a spacing P = 5 mm, an inductance L1 = 10 μH, and a grounding capacitance C1 = 15 pF. Port isolation network: four-segment impedance matching transmission line width w2=1mm, two-group spacing P=5mm, two-group spacing P=28mm, satisfying 2w=W (W=2mm), inductance L4=8μH, grounding capacitance C4=12pF, isolation resistance R1=50Ω; The microstrip transmission line and the T-type transmission line are made of copper, and the dielectric substrate is made of FR-4 material (dielectric constant εr=4.4) with a substrate thickness h=1.6mm.

[0027] (II) Assembly process Copper microstrip transmission lines, T-type transmission lines and impedance matching transmission lines are etched on the FR-4 dielectric substrate to ensure that the line width and spacing meet the design parameters. Weld grounding capacitors C1, C4, and C5, inductors L1 and L4, and isolation resistor R1 at the designated locations. The ends of the isolation resistor R1 are welded together to conduct electricity, and the grounding capacitors are reliably connected to the grounding layer of the substrate. Install the main port (Port1) and six branch ports (Port2-Port7), ensuring that the ports are securely soldered to the transmission lines with a contact resistance of less than 0.1Ω. The assembled power divider is then encapsulated using flame-retardant ABS plastic to ensure mechanical strength and electromagnetic shielding performance.

[0028] (III) Performance Testing The electrical performance of the 1-to-6 power divider in this embodiment was tested, and the results are as follows: Operating frequency band: 32.5MHz~37.5MHz; Return loss: The absolute value of return loss at each port is ≥15dB; Insertion loss: Insertion loss at each port ≤ 3.5dB, and the consistency of insertion loss between ports ≤ 0.3dB; Phase consistency: Within the 32.5MHz~37.5MHz frequency band, the phase difference between each sub-port is ≤5°; Port isolation: The isolation between ports is ≥20dB; External dimensions: 95mm×65mm×15.6mm, with a volume that is 1 / 10 of a conventional power divider in the same frequency band.

[0029] Example 2: One-to-four power divider Based on the above technical solution, by adjusting the number of port matching transmission lines and port isolation networks to four sets, while keeping the total number of port matching transmission lines and the structural parameters of each component unchanged, a one-to-four power divider can be realized. Testing shows that this power divider exhibits a return loss ≥14dB, insertion loss ≤3.2dB, and port isolation ≥19dB in the 32.5MHz~37.5MHz frequency band, with dimensions of 40mm×30mm×5mm, also demonstrating its miniaturization and excellent performance.

[0030] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. A miniaturized power divider for low-frequency applications, characterized in that, The power divider includes a main port matching transmission line, at least two sets of sub-port matching transmission lines, and sub-port isolation networks corresponding to each sub-port matching transmission line. The main port matching transmission line is connected to each sub-port matching transmission line via microstrip transmission lines and T-type transmission lines. The ends of each sub-port matching transmission line are connected to the corresponding sub-port isolation network, and the ends of all sub-port isolation networks are interconnected. The operating frequency band of the power divider is 32.5MHz to 37.5MHz.

2. The miniaturized power divider for low-frequency applications according to claim 1, characterized in that, The total port matching transmission line includes Port1 total port excitation, two impedance matching transmission lines, and grounding capacitor C5; the width of the two impedance matching transmission lines is w0, and the spacing is P=10mm. The grounding capacitor C5 works with the two impedance matching transmission lines to achieve total port impedance matching.

3. A miniaturized power divider for low-frequency applications according to claim 2, characterized in that, The port matching transmission line includes a port, two impedance matching transmission lines, an inductor L1, and a grounding capacitor C1; the width of the two impedance matching transmission lines is w1, and the spacing is P=5mm. The inductor L1 and the grounding capacitor C1 work together to achieve impedance matching between the port and the total transmission path.

4. A miniaturized power divider for low-frequency applications according to claim 3, characterized in that, The port isolation network includes four impedance matching transmission lines, an inductor L4, a grounding capacitor C4, and an isolation resistor R1. The width of each of the four impedance matching transmission lines is w2. The spacing between two sets of transmission lines is P=5mm, and the spacing between the other two sets of transmission lines is P=28mm, satisfying the dimensional relationship 2w=W. The end of the isolation resistor R1 is interconnected with the ends of the isolation resistors of other port isolation networks.

5. A miniaturized power divider for low-frequency applications according to claim 4, characterized in that, In the main port matching transmission line, w0 = 2mm and the grounding capacitor C5 = 10pF; in the sub-port matching transmission line, w1 = 1.5mm, the inductance L1 = 10μH and the grounding capacitor C1 = 15pF.

6. A miniaturized power divider for low-frequency applications according to claim 5, characterized in that, In the split-port isolation network, w2=1mm, W=2mm, the inductor L4=8μH, the grounding capacitor C4=12pF, and the isolation resistor R1=50Ω.

7. A miniaturized power divider for low-frequency applications according to any one of claims 1-6, characterized in that, The microstrip transmission line and the T-type transmission line are made of copper; the dielectric substrate of the power divider is made of FR-4 material, the dielectric constant of the dielectric substrate is εr=4.4, and the thickness is h=1.6mm; the volume of the power divider is 1 / 10 of the volume of a conventional power divider in the same frequency band.

8. A miniaturized multi-path power allocation method for low-frequency band applications, characterized in that, Based on the power divider according to any one of claims 1-7, the implementation includes the following steps: Step 1: The input signal is excited through Port1 and enters the main port matching transmission line. Impedance optimization is completed through the cooperation of two sections of impedance matching transmission line and grounding capacitor C5. Step 2: The optimized signal is evenly distributed to each port matching transmission line via microstrip transmission line and T-type transmission line; Step 3: The signal transmission characteristics are stabilized through the combined action of inductor L1, grounding capacitor C1 and two impedance matching transmission lines at each port. Step 4: The port isolation network suppresses signal interference between ports through the impedance adjustment of four impedance transmission lines, inductor L4, grounding capacitor C4, and the interconnection of isolation resistor R1, ultimately achieving uniform distribution of one input signal to multiple output signals.

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