Waveguide with a curved-wall low-pass filter

A waveguide comprising:

• a low-pass filter portion configured to allow low-frequency electromagnetic energy therethrough and reject high-frequency electromagnetic energy, the low-pass filter portion comprising:
• an input port;
• an output port,
• wherein the input port and the output port have different depths, and
• a cavity feature formed between the input port and the output port, the cavity feature having a greater depth than respective depths of the input port and the output port, the cavity feature comprising:
• a top wall;
• and
• a bottom wall, disposed opposite the top wall, that achieves the greater depth for the cavity feature, the bottom wall comprising at least one curved portion configured to allow the cavity feature to achieve the allowance of the low-frequency electromagnetic energy and the rejection of the high-frequency electromagnetic energy.

A waveguide comprising:

• a low-pass filter portion configured to allow low-frequency electromagnetic energy therethrough and reject high-frequency electromagnetic energy, the low-pass filter portion comprising:
• an input port;
• an output port;
• and
• a cavity feature formed between the input port and the output port, the cavity feature having a greater depth than respective depths of the input port and the output port, the cavity feature comprising:
• a top wall;
• and
• a bottom wall, disposed opposite the top wall, that achieves the greater depth for the cavity feature, the bottom wall comprising at least one curved portion configured to allow the cavity feature to achieve the allowance of the low-frequency electromagnetic energy and the rejection of the high-frequency electromagnetic energy,
• wherein
• the low-pass filter portion comprises a planar side wall extending from the bottom wall to the top wall, and
• the at least one curved portion of the bottom wall is concave relative to the cavity feature and either i) comprises a curved surface extending from the input port to the output port, or ii) comprises a plurality of curved surfaces extending in series from the input port to the output port, each of the plurality of curved surfaces being concave relative to the cavity feature.