Quasi-optical diplexer for millimeter wavelengths

Area of Science:

• Astronomy and Astrophysics
• Electrical Engineering
• Optics and Photonics

Background:

• Millimeter-wave astronomy requires efficient signal and local oscillator (LO) frequency injection into mixers.
• Existing diplexer designs may suffer from losses or noise rejection issues, particularly in complex receiver systems like Cassegrain telescopes.
• Cooled mixers and lens-corrected feed systems in Cassegrain receivers necessitate specialized components for optimal performance.

Purpose of the Study:

• To describe a novel quasi-optical diplexer designed for millimeter-wave applications.
• To present a diplexer that efficiently combines signal and local oscillator (LO) frequencies into a mixer.
• To highlight the diplexer's capability to accept both image and signal bands while minimizing losses and rejecting LO noise.

Main Methods:

• Design and fabrication of a quasi-optical diplexer optimized for millimeter-wave frequencies.
• Integration of the diplexer into a Cassegrain receiver system utilizing a cooled mixer and lens-corrected feed.
• Testing and performance evaluation of the diplexer at 150 GHz using a radio telescope.

Main Results:

• The quasi-optical diplexer demonstrates low insertion loss at both signal and local oscillator (LO) frequencies.
• Effective rejection of local oscillator (LO) noise at the signal frequency was achieved.
• The diplexer's configuration proved suitable for Cassegrain receivers, enhancing signal injection efficiency.

Conclusions:

• The developed quasi-optical diplexer is a high-performance component for millimeter-wave receivers.
• Its design offers significant advantages in terms of signal injection efficiency and noise suppression.
• The successful testing at 150 GHz validates its utility in radio astronomy applications, particularly for Cassegrain systems.