Resistive Power Divider

　　A resistive power divider is a simplified yet versatile RF component that uses resistive networks to split an input signal into multiple output signals. Unlike reactive dividers (e.g., Wilkinson or branch-line types), resistive dividers operate over a broad frequency range but exhibit higher insertion loss and lower isolation between output ports. This makes them ideal for applications where wide bandwidth and simplicity outweigh the need for low loss, such as in test equipment, audio systems, or low-power RF networks.

　　The basic principle of a resistive divider relies on Ohm’s law and Kirchhoff’s circuit laws. For a 2-way divider, two equal resistors (R) are connected in a T-network: the input is applied across the top of the T, and the outputs are taken from the two lower ends. The output voltage at each port is half of the input voltage, resulting in a power split of -6 dB (each port receives 25% of the input power). However, the resistors also absorb power, leading to inherent loss. For example, a 50Ω resistive divider using 100Ω resistors will have an insertion loss of ~6 dB, with 50% of the input power dissipated as heat in the resistors. This heat dissipation limits their use in high-power applications unless high-power resistors (e.g., wire-wound or thick-film types) are employed.

　　One key advantage of resistive dividers is their frequency independence. Since they lack reactive elements (inductors or capacitors), they can operate from DC up to microwave frequencies with minimal phase or amplitude variation. This makes them suitable for broadband applications like signal monitoring in spectrum analyzers or combining signals from different frequency sources. In audio engineering, resistive dividers are used to create headphone splitters or to mix signals from multiple microphones, where the wide bandwidth and low cost outweigh the loss of audio amplitude (which can be compensated by amplifiers).

　　However, the trade-offs with resistive dividers are significant. The lack of isolation between output ports means that a mismatch at one port will affect all other ports, causing signal reflections and potential distortion. For example, if one output is terminated with an impedance other than the design value, the input impedance of the divider changes, leading to VSWR (voltage standing wave ratio) degradation. Additionally, the power dissipation in resistors can cause thermal drift, altering the divider’s performance over time in high-temperature environments. To mitigate this, designers often use temperature-stable resistors (e.g., metal-film resistors with low TCR) and ensure adequate heat sinking for high-power applications.

　　In summary, resistive power dividers are valued for their simplicity, broadband operation, and low cost, but they are best suited for low-power, non-critical signal distribution tasks. For high-performance RF systems requiring low loss and high isolation, reactive dividers or active power splitters (using amplifiers) are preferred.

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