Waveguide Circulator
Waveguide Circulator is a non-reciprocal microwave device used to route RF signals between multiple ports with high isolation. Widely applied in radar transmitters, satellite communication systems and high-power microwave equipment.
High-Isolation Waveguide Circulators for Non-Reciprocal Signal Routing
AO Microwave’s high-performance waveguide circulators are non-reciprocal 3-port or 4-port passive devices engineered to route microwave and millimeter-wave signals sequentially from port to port with minimum loss. Machined from solid aluminum or copper housings, these junctions incorporate highly stable gyromagnetic ferrites—such as Yttrium Iron Garnet (YIG) and Nickel-Zinc (NiZn) ferrites—biased by high-coercivity Samarium-Cobalt (SmCo) or Neodymium (NdFeB) permanent magnets. Operating across standard bands up to 110 GHz (WR-90 to WR-10), our circulators deliver an outstanding typical isolation of > 20 dB per junction, low insertion losses of < 0.25 dB, and a stable input VSWR of < 1.20:1 across the band.
By utilizing the tensor permeability characteristics of magnetically biased ferrites, our waveguide circulators permit unidirectional wave propagation (e.g., Port 1 to Port 2, Port 2 to Port 3, and Port 3 to Port 1). They are critical for sharing a single antenna between transmitter and receiver lines (duplexing), routing signals in multi-frequency transceivers, and protecting active components in high-power radar and satellite communication systems.
| Part No | Frequency/GHz | Bandwidth | VSWR (Max) | IL/dB (Max) | Isolation/dB (Min) | Flange Type |
|---|---|---|---|---|---|---|
| AO650-WCICPA | 1.13-1.73 | 0.05 | 1.2 | 0.3 | 20 | UDR14 |
| AO510-WCICPA | 1.45-2.20 | 0.05 | 1.2 | 0.3 | 20 | UDR18 |
| AO430-WCICPA | 1.72-2.61 | 0.05 | 1.2 | 0.3 | 20 | UDR22 |
| AO340-WCICPA | 2.17-3.30 | 0.05 | 1.2 | 0.3 | 20 | UDR26 |
| AO284-WCICPA | 2.60-3.95 | 0.05 | 1.2 | 0.3 | 20 | UDR32 |
| AO229-WCICPA | 3.22-4.90 | 0.1 | 1.2 | 0.3 | 20 | UDR40 |
| AO187-WCICPA | 3.94-5.99 | 0.1 | 1.2 | 0.3 | 20 | UDR48 |
| AO159-WCICPA | 4.64-7.05 | 0.1 | 1.2 | 0.3 | 20 | UDR58 |
| AO137-WCICPC | 5.38-8.17 | 0.1 | 1.2 | 0.3 | 20 | UDR70 |
| AO112-WCICPC | 6.57-9.99 | 0.1 | 1.2 | 0.3 | 20 | UBR84 |
| AO90-WCICPC | 8.20-12.5 | 0.1 | 1.2 | 0.3 | 20 | UBR100 |
| AO75-WCICPC | 9.84-15.0 | 0.1 | 1.2 | 0.3 | 20 | UBR120 |
| AO62-WCICPC | 11.9-18.0 | 0.1 | 1.2 | 0.3 | 20 | UBR140 |
| AO51-WCICPC | 14.5-22.0 | 0.1 | 1.2 | 0.3 | 20 | UBR180 |
| AO42-WCICPC | 17.6-26.7 | 0.1 | 1.2 | 0.3 | 20 | UBR220 |
| AO34-WCICPC | 21.7-33.0 | 0.1 | 1.2 | 0.3 | 20 | UBR260 |
| AO28-WCICPC | 26.5-40.0 | 0.1 | 1.2 | 0.3 | 20 | UBR320 |
| AO22-WCICPC | 33.0-50.0 | 0.05 | 1.3 | 0.6 | 18 | UG-383/U |
| AO19-WCICPC | 40.0-60.0 | 0.05 | 1.3 | 0.6 | 18 | UG383/UM |
| AO15-WCICPC | 50.0-75.0 | 0.05 | 1.3 | 0.6 | 18 | UG385/U |
| AO12-WCICPC | 60.0-90.0 | 0.05 | 1.3 | 0.8 | 18 | UG-387/U |
| AO10-WCICPC | 75.0-110.0 | 0.05 | 1.3 | 1 | 18 | UG387/UM |
The Electromagnetics of Biased Ferrite Junctions
Waveguide circulators achieve non-reciprocal signal routing through the anisotropic magnetic properties of biased ferrites. When an external permanent magnet applies a static magnetic bias along the vertical axis of a ferrite disk, it splits the incident wave into two counter-rotating circularly polarized components that travel at different phase velocities (Faraday rotation).
By mathematically matching the ferrite diameter and the applied magnetic field, we ensure that the two wave components add constructively in-phase at the desired output port (e.g., Port 2) while canceling out completely at the isolated port (Port 3). AO Microwave utilizes high-uniformity Samarium-Cobalt (SmCo) magnets to maintain a constant magnetic bias, securing stable isolation across wide temperature variations.
Target Applications & Operational Advantages
By providing non-reciprocal signal routing and high port-to-port isolation, our waveguide circulators enable efficient duplexing and protection:
Radar Antenna Transceiver Duplexers
Function: Connects a single shared antenna to both high-power transmitter and sensitive receiver paths.
Advantage: Routes high transmit power to the antenna while protecting the receiver LNA from damage, maintaining low insertion loss.
Active Amplifier Output Protection
Function: Directs reflected signals from antenna mismatches into an external load, protecting active amplifiers.
Advantage: High isolation prevents reflected power from feeding back into and damaging delicate SSPA output transistors.
Multi-Channel Multiplexing Networks
Function: Stacks multiple transmit or receive carrier frequencies onto a single physical feed line.
Advantage: Extremely low passband insertion loss (<0.25 dB) preserves signal power and maintains high system efficiency.
Waveguide Circulator FAQs
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