The Wilkinson Divider Is a Superior Choice for Splitting RX Antennas

Or: Antenna system design meets RF hygiene.

In receive-only antenna systems—especially with broadband active antennas, multicouplers, or phased arrays—the way you split and distribute signals across multiple receivers matters. Many reach for a diplexer or a simple “T/Y” splitter, but when you need multiple receivers to monitor the same spectrum with predictable impedance and minimal interaction, a properly designed Wilkinson power divider is usually the cleaner choice.

Diplexers: Selective, Not a General-Purpose Splitter

A diplexer is a frequency-selective device. It uses filter networks (typically low-pass and high-pass, or band-pass sections) to separate or combine different frequency bands into one port.

• They’re ideal when you have two non-overlapping bands that must share one feedline or one antenna port.
• Within their intended bands, well-designed diplexers can provide good matching and strong isolation between the “low” and “high” ports.
• They are not intended to create two equal copies of the same broadband signal.

They’re fine for splitting 144 MHz from 430 MHz—but not when both receivers need the same 1–30 MHz (or VHF/UHF) spectrum.

Wilkinson Divider: Matched and Isolated (Over Its Design Band)

The Wilkinson divider is a matched power divider/combiner that uses transmission-line sections (or lumped/transformer equivalents) plus an isolation resistor between output ports. In a typical 2‑way equal split, each receiver sees roughly −3 dB of split (plus small real-world losses), while the ports stay well-behaved over the intended bandwidth.

• Good impedance match at all ports across the design band
• High port-to-port isolation that reduces receiver-to-receiver backfeed
• Predictable amplitude and phase balance (useful for coherent RX, diversity, or array work)

Note: a classic single-section (quarter-wave) Wilkinson is relatively narrowband around its design frequency. For wideband coverage (especially at HF), use multi-section designs or lumped/transformer implementations intended for the bandwidth you need.

When Noise Matters: Choose Isolation (and a Stable Load)

Receive systems live or die on noise performance. Imagine a shared broadband active antenna feeding:

• Receiver A for a waterfall/skimmer
• Receiver B for main listening, recording, or diversity

A diplexer can’t help if both receivers need the same band. And a simple “T/Y” split gives each receiver an easy path into the other, while also presenting the antenna’s active stage with a load that can shift as receivers change modes or impedance.

A proper resistive splitter is broadband and provides reasonable isolation, but it typically costs extra insertion loss (often around 6 dB for a 2‑way split). If that loss occurs ahead of any gain, it directly hurts system noise figure.

A Wilkinson keeps the source properly terminated and greatly reduces receiver-to-receiver crosstalk—helping prevent SDR LO leakage, digital hash, or front-end noise from one device from contaminating the other (or feeding back toward the antenna amplifier).

Bonus: Wilkinson Scalability

Wilkinsons can be scaled for 4-way, 8-way, or more using cascaded stages (and can also be designed for unequal splits). They can be built for 50 Ω, 75 Ω, or other system impedances, and realized with microstrip/stripline at VHF/UHF and higher, or with lumped/transformer approaches where transmission-line quarter-waves are impractical (e.g., HF).

Bottom Line

• Can be designed for broad bandwidths (when implemented appropriately)
• Provides superior isolation between receivers compared to simple splits
• Maintains a stable, matched load for both the antenna system and the receivers (within the design band)
• Helps prevent inter-device interference in real-world SDR-heavy RX setups

For serious RX systems—especially those using active antennas or multiple SDRs—the Wilkinson is often the difference between “it works” and “it’s clean.”

When you split, don’t just divide—isolate.

Interested in more technical content? Subscribe to our updates for deep-dive RF articles and lab notes.

Questions or experiences to share? Feel free to contact RF.Guru.