In the field of microwave technology, a power divider, also known as a power splitter, is a key passive device used to divide the energy of an input signal into two or more equal or unequal outputs. It can also operate in reverse, that is, to combine the energy of multiple signals into one output, which is called a combiner. Power dividers are widely used in microwave and RF systems, such as antenna arrays, radar systems, communication equipment, etc.1

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　　Working principle of microwave power divider

　　1. Basic concept

　　A power divider is a three-port or multi-port network that can distribute the power of an input port to two or more output ports in a predetermined ratio. Ideally, for a half-power divider, the power on each output port will be half of the input power minus 3 dB (i.e., power loss). In addition, the power divider should ensure good isolation between all output ports and no reflection at the input port when all output ports are connected to matched loads2

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　　2. Power divider type

　　Resistive type: uses three equal-value resistors to form a star configuration, which is suitable for broadband applications but has large insertion loss.

　　Wilkinson type: By introducing a terminal resistor to achieve good port-to-port isolation, it has low insertion loss and is suitable for narrowband applications. The Wilkinson power divider was named after its inventor Ernest Wilkinson and was first proposed in the early 1960s. Its design uses three equivalent resistor networks to achieve power distribution, ensuring good matching between input and output and reducing signal reflection and interference5

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　　Hybrid type: Combining the advantages of transmission lines and resistors, it can provide better performance over a wider frequency range, such as branch line directional couplers. This type of power divider can be further subdivided into microstrip power dividers, stripline power dividers, coaxial cavity power dividers, and waveguide power dividers. Choose the appropriate design based on the specific application scenario13

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　　3. Technical indicators

　　The main technical parameters of the power divider include but are not limited to:

　　Frequency range: refers to the frequency band in which the power divider can work effectively.

　　Divide ports: divided into two power dividers, three power dividers, four power dividers and other different forms.

　　Insertion Loss: Indicates the energy loss after the signal passes through the power divider, usually measured in dB.

　　Isolation: Measures the degree of mutual influence between the output ports. The higher the value, the better.

　　Voltage Standing Wave Ratio (VSWR): Reflects the impedance matching between the power divider and the connected circuit.

　　Power Rating: Refers to the maximum power level that the power divider can withstand.

　　Connector Type: Common standard RF connectors such as SMA and N-type8

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　　Application Scenarios

　　In microwave and millimeter wave circuits, especially in the feeding network of array antennas, power dividers can divide one signal into multiple signals; applied to microwave solid-state amplifiers, multiple signals can be combined into a larger output signal14

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　　In antenna array systems, power dividers are used to distribute an input signal to multiple transmitting antennas in order to form a specific directional pattern or increase gain9

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　　For applications that require precise control of phase and amplitude, such as phased array radar, the Wilkinson power divider is the preferred solution due to its excellent phase consistency5

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　　Design and Optimization

　　Designers have proposed different physical structures to build microwave power dividers, such as parallel coupled line resonators loaded with varactors, microstrip hairpin bandpass filters, and designs based on step impedance resonators. Each structure has its own unique advantages, such as compact size, high selectivity, and easy integration7

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　　Modern microwave power dividers often integrate digital control functions, which not only simplifies the system configuration process, but also improves the degree of automation. For example, in some cases, the power division ratio or operating frequency can be dynamically changed by adjusting the internal component parameters to adapt to a wider range of application requirements10

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