Modification of Corrugated Microwave Choke Structures

Initial Problem

At both the entrance and exit ends of the microwave oven cavity, corrugated choke structures are used to prevent microwave energy from escaping. These metallic assemblies contain a series of precisely spaced pockets that act as band-stop filters, tuned to suppress the magnetron tube’s operating frequency. However, the height and width of the existing choke openings inherently limit the maximum profile size that can be processed without exceeding acceptable leakage levels. As end users began needing to process larger product profiles, the original chokes became a physical constraint.

Objective

Expand the system’s capability to handle larger product profiles.
Maintain or improve microwave energy containment despite increased choke opening dimensions.
Ensure compliance with safety and emission standards for microwave leakage.

MES Solution

Removed the original corrugated chokes located at both ends of the oven cavity.
Modified the oven cavity structure to accommodate larger replacement chokes.
Thoroughly cleaned the vestibule sections of the oven cavity where the chokes interface, ensuring a clean mounting surface and reliable installation.
Installed newly fabricated corrugated choke structures with expanded height and width to support the desired larger profile dimensions.
Lined the vestibule areas with microwave-absorbing material, adding a secondary layer of containment protection.
Mounted a new tunnel enclosure to the oven’s end stubs:
These enclosures were also lined with microwave-absorbing material.
Designed to enhance suppression of leakage and further reduce stray microwave emissions from the enlarged choke openings.

Results

Successfully expanded profile capacity, allowing end users to run larger dimension parts without violating leakage limits.
Maintained microwave containment performance through combined use of redesigned chokes, absorbing materials, and tunnel shielding.
Extended the long-term usability and flexibility of the existing oven system for future high-volume or oversized product runs.

Before

After