Power Divider Principles, Types, and Core Applications in 5G, Radar, and Other Fields

I. Power Divider Overview
A power divider is a passive RF/microwave device that distributes input signal power to multiple output ports in a specific ratio while ensuring isolation between the ports. It plays a key role in modern wireless communications, radar, test and measurement, and other fields, directly impacting the efficiency and stability of system signal distribution.

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II. Power Divider Operating Principle
A power divider distributes power through internal transmission lines (such as microstrip, stripline, or waveguide). Its core specifications include:
- Distribution ratio: e.g., equal (3dB) or unequal (6dB/10dB).
- Isolation: The ability to isolate the signals between output ports (typically >20dB).
- Insertion loss: The power loss of a signal passing through the device (ideally 0, practically ≤0.5dB).
- Amplitude/phase balance: The signal consistency between each output port (e.g., within ±0.5dB).

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III. Common Types of Power Splitters
1. Wilkinson Power Splitters
- Features: High isolation achieved through a λ/4 transmission line and isolation resistors, suitable for narrowband applications.
- Frequency Band: DC-18 GHz (e.g., 2.4 GHz WiFi, 5G Sub-6 GHz).
- Advantages: Simple structure, low cost, suitable for PCB integration.

2. Resistive Power Splitters
- Features: Power distribution achieved through a pure resistive network, with no frequency restrictions but poor isolation.
- Applications: Non-critical scenarios such as low-frequency testing and signal monitoring.

3. Waveguide Power Splitters
- Features: Based on a metal waveguide structure, supports high power and millimeter-wave frequency bands.
- Frequency Band: 18-110 GHz (e.g., radar and satellite communications).
- Advantages: Low loss (<0.1 dB), high power handling (>100 W).

4. Broadband Multi-section Power Splitter
- Features: Multi-stage coupling structure extends bandwidth, covering 2-40 GHz.
- Applications: Electronic warfare, broadband test systems.

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IV. Core Application Scenarios of Power Splitter
1. 5G Communication Systems
- Massive MIMO Antenna Arrays: Power splitters provide equal-amplitude and in-phase excitation for multiple antenna elements, ensuring beamforming accuracy.
- Example: In a 3.5 GHz 64T64R base station, an 8-way power splitter distributes signals to subarrays.
- Millimeter-wave Repeater: Power splitters in the 28 GHz/39 GHz bands require low insertion loss (<0.3 dB) and miniaturization (LTCC process).

2. Radar and Electronic Warfare
- Phased Array Radar: Power splitters distribute local oscillator signals to multiple TR components, requiring phase consistency (within ±5°).
- Example: X-band (8-12 GHz) military radars use waveguide power splitters with a pulse power tolerance of 1 kW.
- Electronic Countermeasures (ECM): Power splitters are used to achieve multi-path transmission of interference signals.

3. Satellite Communications (SATCOM)
- Onboard Payloads: Power splitters distribute signals to multi-feed parabolic antennas, requiring lightweight (aluminum cavity) and low PIM (<-150dBc).
- Ground Stations: Ka-band (26-40GHz) power splitters support high-throughput satellite signal distribution.

4. Test and Measurement
- Multi-port Network Analysis: Power splitters provide reference signals for S-parameter testing.
- Requirements: Broadband (DC-40GHz) and high amplitude balance (±0.2dB).
- Production Line Testing: Resistive power splitters offer fast splitting, with cost as a priority.

5. Internet of Things and Consumer Electronics
- WiFi 6/6E Routing: 4×4 MIMO systems rely on 2.4/5GHz power splitters to reduce the cost of multiple antennas.
- Automotive millimeter-wave radar: 77GHz power splitters integrated on the PCB support short-range detection.

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V. Key Parameters for Power Splitter Selection
| Parameters | Typical Values | Impact Scenarios |
|------------------|--------------------------|---------------------------|
| Frequency Range | DC-40GHz | Millimeter-wave requires waveguide or LTCC process |
| Power Capacity | 1W-1kW | High power for radar, low power for IoT |
| Insertion Loss | <0.5dB | Impacts system link budget |
| Isolation | >20dB | Multi-antenna systems require >30dB |
| Phase Balance | Within ±5° | Core requirement for phased array radar |

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VI. Future Trends
1. Integration: Integration with filters and amplifiers (such as AiP antenna modules).
2. High Frequency: Accelerated R&D of terahertz (THz) power splitters (>100GHz).
3. Intelligence: Tunable Power Splitter (Dynamically Adjusting the Distribution Ratio Using PIN Diodes).

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Conclusion
As the "traffic hub" of RF systems, the performance of power splitters directly determines the reliability of equipment such as communications and radar. With the widespread adoption of 5G/6G, satellite internet, and autonomous driving, the demand for high-performance, miniaturized power splitters will continue to grow. Engineers must select the optimal solution based on the frequency, power, and cost of the application.