Novel orthomode transducer for millimeter wave and terahertz frequencies. Design, fabrication and characterization of novel probe-based orthomode transducer
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Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Wireless, photonics and space engineering (MPWPS), MSc
Publicerad
2023
Författare
Patriksson, Nils
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
There exist a vast number of orthomode transducer designs for microwave frequen cies. At sub-millimeter wave frequencies however, high accuracy requirements are
set on the manufacturing techniques. This work seeks to design a novel orthomode
transducer combining different manufacturing techniques resulting in low loss, wide
bandwidth and a compact design. These are all important parameters for radio astronomy applications.
Several design ideas from literature are considered. Room for improvement is iden tified and the novel design is developed using an electromagnetic full-wave solver.
Fabrication of two demonstrator devices is done using CNC milling and micro fabrication in a clean-room environment. Lastly, the demonstrators are character ized.
In summary, an orthomode transducer working between 270 − 385 GHz (36% frac tional bandwidth) was demonstrated. The produced devices work as proof of concept
with insertion loss of 2 dB and return loss of 15 dB achieved for both polarizations
symmetrically at room temperature. It is concluded that insertion loss of less than
1 dB and return loss of more than 20 dB are possible to achieve with further im provements of the design. The design is in theory scale-able to 1 THz and could be
used instead of quasi-optical polarization diplexers. The design is also very compact.
Beskrivning
Ämne/nyckelord
orthomode transducer, terahertz, millimeter wave, sub-millimeter wave, orthomode junction, polarization diplexer, polarimetry