Get Connected: A Brief Waveguide Introduction

We recently got ahold of several new waveguide products, and tested several waveguide straights, bends, and twists to generate s-parameter files you can download on our product pages.

Before we start making new connections, let’s break down the waveguide structure and how to connect different waveguide sections. Below is the flange of a WR-19 waveguide:

Figure 1. WR-19 Rectangular Waveguide Flange.

The typical waveguide flange has at least 4 threaded holes to screw different waveguide sections together with standard #4-40 thread size 3/32” socket head screws. In the case that screw holes are not threaded, hex nuts on the receiving flange can be used to secure the two waveguides. To ensure accurate alignment, in particularly for small waveguides, alignment pins are installed and slot into alignment holes on the receiving flange. Figure 2 below shows several coax to waveguide adapters to test waveguide products on our VNA:

Figure 2. Coax to Waveguide Adapters for WR-15, WR-19, WR-22, and WR-28 (left to right).

In case you aren’t familiar with WR-xx standard, the following table lists a few of the Electronic Industries Alliance’s (EIA) WR designations for standard rectangular waveguides available at Marki:

Table 1. EIA Code Recommended Frequency Range.

Before assembling your waveguide, ensure that there is no debris within the waveguide and on the flange surface. When connecting waveguides together, the screws should be tightened in a diagonal pattern as seen below:

Figure 3. Waveguide Screw Pattern.

Finger tighten the screws initially, then use a 3/32” hex waveguide screw driver to secure the screws. Do not overtighten the screws to prevent damage to the flange surface or threading.

Figure 4. WR-15 2” Waveguide Straight.

Figure 5. WR-15 1” H-Bend Waveguide.

Figure 6. WR-15 1” 90° Waveguide Twist with Proxi-Flange Adapters.

The following plots show the measurement results for the products shown above:

Figure 7. WS-1500200WG Performance Plots.

Figure 8. WH90-1500WG Performance Plots.

Figure 9. WT90-1500WG Performance Plots.

Without a solid connection, the waveguide performance will decrease dramatically as seen below:

Figure 10. WT90-1500WG Insertion Loss with Poorly Screwed Waveguides.

Marki’s recent dive into waveguide products have introduced a broad collection of waveguide straights, bends, twists, terminations, couplers, and many other components found here. Feel free to reach out to sales@markimicrowave.com for any purchasing inquiries or support@markimicrowave.com for any technical questions and support.