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Wideband Isolators - WBI


  • Low insertion loss
  • High isolation
  • Compact size
  • Cryogenically coolable (option)


  • Radioastronomy
  • Wideband subsystems
  • Instrumentation/test sets
  • Plasma diagnostics

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Download the WBI specsheet (.pdf)


Millitech series WBI isolators are the lowest loss, smallest size, wide bandwidth isolators available in the industry, making them ideally suited for applications requiring small size and wide bandwidth. Other inherent attributes are high isolation and flat frequency response.

These isolators are offered in two configurations: E- to H-plane and E- to E-plane. This feature eliminates the need for waveguide twists and is ideal for applications where space is limited. A more detailed description of these configurations can be found on the following pages.

Series WBI isolators feature lower insertion loss and a more compact size than the series FBI fullband isolators and are a wider bandwidth than the JFD junction isolators.

The WBI isolators can be cryogenically cooled to 77K for lower insertion loss performance. An option for testing at LN2 temperature is provided in the “How to Order” section.

Electrical Specifications

Model Number WBI-10 WBI-08 WBI-06 WBI-05 WBI-04
Frequency range (GHz) 82 – 110 90 – 140 115 – 170 140 – 215 170 – 260
Insertion loss (dB) (typ) (ambient) 0.9 1.3 1.9 2.3 2.5
Isolation (dB) (min) (ambient) 20 20 20 20 20
VSWR (max) (ambient) 1.5:1 1.6:1 1.6:1 1.6:1 1.6:1
Insertion loss (dB) (typ) (cryo) 0.5 0.8 1.0 1.4 1.6
Isolation (dB) (min) (cryo) 23 22 21 20 20

All data includes mismatch due to port configuration
Maximum input power is 26 dBm

Outline Drawing (WBI-10-RE000)*

WBI - Outline Drawings
A WBI-10 WBI-08 WBI-06 WBI-05 WBI-04
.750 .463 .409 .331 .272

*The outlines shown may not reflect the latest information. Please contact Millitech for current outline drawings.
Note: All dimensions are in inches.

Mechanical Specifications

Model Number WBI-10 WBI-08* WBI-06* WBI-05* WBI-04*
Flange MIL-DTL-3922 /67C-010 /67C-M08 /67C-M06 /67C-M06 /67C-M06

*Flange Pattern Compatible with MIL-DTL-3922/67C. Refer to IS000131.

Typical Measured Data

WBI - Actual Data


E- to E-Plane Configuration

E- to H-Plane Configuration

WBI - E-Plane to E-Plane Configuration WBI - E-Plane to H-Plane Configuration

How to Order:

Specify Model Number
Y = Flange Type
  • A – Precision, Flat (WR-08 to WR-04)
  • R – Round (WR-10)
B = Input-to-Output Configuration
  • E – E- to E-plane
  • H – E- to H-plane
C = Cooling Options
  • C – Cryogenic
  • 0 – Standard

To Order: series WBI in WR-10 with a round flange with an input-to-output configuration of E- to E-plane

Specify: WBI-10-RE000