Waveguide Isolator
Waveguide Isolator protects microwave sources from reflected power by allowing RF energy to pass in only one direction. Ideal for radar systems, RF amplifiers, satellite transmitters and microwave communication networks.
High-Performance Waveguide Isolators for Active Source Protection
AO Microwave’s high-isolation waveguide isolators are non-reciprocal passive devices designed to transmit RF and microwave signals in the forward direction (Port 1 to Port 2) with minimum loss, while absorbing reflected energy traveling in the reverse direction. Precision-machined from solid aluminum and copper alloys, these isolators integrate a biased ferrite junction and a high-performance, low-reflection termination load internally on the isolated third port. Operating up to 110 GHz (WR-90 to WR-10), our isolators deliver an outstanding isolation of typically > 20 dB (with dual-junction models exceeding 40 dB), low insertion losses of < 0.25 dB, and a low input VSWR of < 1.20:1 across the band.
By isolating the signal source from downstream impedance mismatches, our waveguide isolators prevent frequency pulling, power variations, and active component damage. They are critical for protecting solid-state power amplifiers (SSPAs) in transmitters, stabilizing local oscillators (LO), and ensuring accurate measurements on high-frequency test benches.
| Part No | Frequency/GHz | Bandwidth | VSWR (Max) | IL/dB (Max) | Isolation/dB (Min) | Flange Type |
|---|---|---|---|---|---|---|
| AO650-WISOPA | 1.13-1.73 | 0.05 | 1.2 | 0.3 | 20 | UDR14 |
| AO510-WISOPA | 1.45-2.20 | 0.05 | 1.2 | 0.3 | 20 | UDR18 |
| AO430-WISOPA | 1.72-2.61 | 0.05 | 1.2 | 0.3 | 20 | UDR22 |
| AO340-WISOPA | 2.17-3.30 | 0.05 | 1.2 | 0.3 | 20 | UDR26 |
| AO284-WISOPA | 2.60-3.95 | 0.05 | 1.2 | 0.3 | 20 | UDR32 |
| AO229-WISOPA | 3.22-4.90 | 0.1 | 1.2 | 0.3 | 20 | UDR40 |
| AO187-WISOPA | 3.94-5.99 | 0.1 | 1.2 | 0.3 | 20 | UDR48 |
| AO159-WISOPA | 4.64-7.05 | 0.1 | 1.2 | 0.3 | 20 | UDR58 |
| AO137-WISOPC | 5.38-8.17 | 0.1 | 1.2 | 0.3 | 20 | UDR70 |
| AO112-WISOPC | 6.57-9.99 | 0.1 | 1.2 | 0.3 | 20 | UBR84 |
| AO90-WISOPC | 8.20-12.5 | 0.1 | 1.2 | 0.3 | 20 | UBR100 |
| AO75-WISOPC | 9.84-15.0 | 0.1 | 1.2 | 0.3 | 20 | UBR120 |
| AO62-WISOPC | 11.9-18.0 | 0.1 | 1.2 | 0.3 | 20 | UBR140 |
| AO51-WISOPC | 14.5-22.0 | 0.1 | 1.2 | 0.3 | 20 | UBR180 |
| AO42-WISOPC | 17.6-26.7 | 0.1 | 1.2 | 0.3 | 20 | UBR220 |
| AO34-WISOPC | 21.7-33.0 | 0.1 | 1.2 | 0.3 | 20 | UBR260 |
| AO28-WISOPC | 26.5-40.0 | 0.1 | 1.2 | 0.3 | 20 | UBR320 |
| AO22-WISOPC | 33.0-50.0 | 0.05 | 1.3 | 0.6 | 15 | UG-383/U |
| AO19-WISOPC | 40.0-60.0 | 0.05 | 1.3 | 0.6 | 15 | UG383/UM |
| AO15-WISOPC | 50.0-75.0 | 0.05 | 1.3 | 0.6 | 15 | UG385/U |
| AO12-WISOPC | 60.0-90.0 | 0.05 | 1.3 | 0.8 | 15 | UG-387/U |
| AO10-WISOPC | 75.0-110.0 | 0.05 | 1.3 | 1 | 15 | UG387/UM |
The Physics of Reflection Absorption inside Isolated Ports
Waveguide isolators operate on the non-reciprocal principles of biased ferrites. When a forward-traveling wave enters Port 1, the biased ferrite junction rotates its E-field polarization to couple efficiently into the output at Port 2, exhibiting low insertion loss.
However, when a reflected wave enters Port 2 from a downstream mismatch, the biased ferrite rotates its polarization in the same direction, routing the reflected wave into the isolated third port. This third port is terminated with a high-performance ceramic termination load, which absorbs the reflected energy completely and converts it into heat, preventing reflections from feeding back into the signal source at Port 1.
Target Applications & Operational Advantages
By providing high reverse isolation and low insertion loss, our waveguide isolators protect critical microwave signal sources:
Active SSPA Output Protection
Function: Placed at the output of high-power transmitters to protect the active amplifiers from antenna mismatches.
Advantage: Absorbs 100% of reflected power from open or shorted lines, preventing physical damage and thermal failure in active GaN or GaAs transistors.
Local Oscillator (LO) Frequency Stabilization
Function: Placed at the output of sensitive oscillators to isolate them from load variations.
Advantage: High reverse isolation (>20 dB) prevents "frequency pulling" and power fluctuations, maintaining stable LO generation.
High-Frequency Test Bench Source Isolation
Function: Connects signal generators and VNAs to devices under test (DUT) with poor match characteristics.
Advantage: Low VSWR and high isolation prevent reflected waves from corrupting measurements, ensuring accurate, repeatable references.
Waveguide Isolator FAQs
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