Mi-Wave · Waveguide Passive Components
680/681 Series Waveguide Twists
Rotate the polarization plane by 45 or 90 degrees, from 8.2 GHz to 325 GHz
The Mi-Wave 680 and 681 Series are precision rectangular waveguide twists that rotate the polarization of the field inside the guide while keeping transmission clean. The 680 Series twists 45 degrees and the 681 Series 90 degrees; both are made in left-hand and right-hand versions so the part matches the routing. Thirteen waveguide bands cover 8.2 GHz to 325 GHz, X-band through J-band, which makes the twist a routine part of microwave, mm-wave and sub-mm-wave integration. Evencat is an authorized Mi-Wave distributor in Taiwan.
Overview
A 680/681 twist rotates the polarization plane gradually along its length, which suppresses mode conversion and keeps insertion loss and reflection low. Both the 45-degree 680 Series and the 90-degree 681 Series carry standard flanges and drop into existing RF and mm-wave runs. The line covers X, K, Ka, Q, U, V, E, W, F, D, G, H and J bands, with typical VSWR as low as 1.06:1. Every model is available left-hand or right-hand, and an outline drawing and test data are available for system design. Twists are the usual polarization adapter between ferrite components and other polarization-sensitive passives, and they appear in satellite, aerospace, defense radar and mm-wave measurement systems. When you order, state the angle, the band and the hand of rotation (RH or LH); the X-band 680X is rated at VSWR 1.2 while the 681X and every K-band and Ka-band part holds 1.06:1.
Key specifications
| Twist angle (680 Series) | 45° (left-hand / right-hand) |
|---|---|
| Twist angle (681 Series) | 90° (left-hand / right-hand) |
| Frequency range | 8.2 GHz – 325 GHz |
| Typical VSWR (X-band, WR-90) | 1.06:1 – 1.2:1 |
| Typical VSWR (V/W bands, WR-15/WR-10) | 1.15:1 |
| X-band models (8.2–12.4 GHz) | 680X/39 / 681X/39, WR-90, flange UG-39/U |
| K-band models (18–26.5 GHz) | 680K/595 / 681K/595, WR-42, flange UG-595/U |
| Ka-band models (26.5–40 GHz) | 680A/599 / 681A/599, WR-28, flange UG-599/U |
| Q-band models (33–50 GHz) | 680B/383 / 681B/383, WR-22, flange UG-383/U |
| V-band models (50–75 GHz) | 680V/385 / 681V/385, WR-15, flange UG-385/U |
| W-band models (75–110 GHz) | 680W/387 / 681W/387, WR-10, flange UG-387/U |
| J-band models (220–325 GHz) | 680J/387 / 681J/387, WR-3, flange UG-387/U |
Features
45° and 90° in two series
The 680 Series twists 45 degrees and the 681 Series 90 degrees, each in left-hand and right-hand versions, so the part matches the routing and the polarization you need.
8.2–325 GHz in one family
Thirteen waveguide bands, X through J, cover microwave, mm-wave and sub-mm-wave systems from a single product line.
Low VSWR, low insertion loss
Close tolerances give a typical VSWR as low as 1.06:1, and the gradual twist geometry suppresses mode conversion so reflection and loss stay small.
Standard flanges
UG flanges (UG-39/U, UG-595/U, UG-383/U and the rest) let the twist mate with existing rectangular waveguide runs without an adapter.
Pairs with ferrite components
Twists are the polarization adapter in front of or behind isolators, circulators and polarizers, and appear throughout Mi-Wave ferrite assemblies.
Built for aerospace, satellite and defense
The parts are designed for high-reliability systems and are used in satellite links, aerospace payloads, defense radar and mm-wave instrumentation.
Typical applications
Satellite communications
Aligning feed polarization at a ground station
In VSAT and SatCom earth stations the E-field of the feed horn often does not line up with the waveguide run to the LNA. A 681 Series 90-degree twist between the two aligns horizontal or vertical polarization without re-mounting the antenna, so cross-polar isolation and gain are preserved.
Radar and defense
Rotating polarization in radar array routing
Waveguide in phased-array radar and EW equipment has to work around structure, so sub-array ports end up facing different planes. A 45-degree 680 and a 90-degree 681 can be cascaded to rotate the guide cross-section as needed without adding reflection, which simplifies airborne and shipboard RF layouts.
Measurement lab
Correcting port orientation in VNA test chains
In S-parameter measurements from 8 GHz to 325 GHz the DUT port is frequently not parallel to the extender port. Adding a 680/681 twist to the chain removes the mechanical strain and gap leakage that come from forcing flanges together, so repeatability and insertion loss stay consistent.
Options and configuration
Choose the band, twist angle and hand of rotation for your system; the selections are collected into a list and carried into the quote form.
Twist angle
Band and waveguide size
Hand of rotation
Downloads
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