Abstract
A very compact waveguide orthomode transducer (OMT) is described in this paper. The design is characterized with a twofold rotationally symmetric cross-section in the probing area, adapted from a side-coupling OMT design, simultaneously enabling low port-to-port coupling and high cross-polarization discrimination (XPD) over a fractional bandwidth of about 15–20%. Compared to previously reported compact waveguide OMTs, the proposed design is simpler, thus facilitating its manufacture at millimeter-wave frequencies. The concept is demonstrated with a design in the K-band for a broadband communication satellite downlink over the frequency band of 17.3–20.2 GHz. For test purposes, transitions to standard waveguide WR42 are included, and the OMT is assembled with a conical horn antenna. The measured reflection and coupling coefficients are below −19.5 dB and −22.9 dB, respectively, over the nominal bandwidth, and they are in good agreement with the simulation’s results. The on-axis XPD, measured in an anechoic chamber, is better than 30 dB over the nominal bandwidth, which is also in line with simulations. The proposed waveguide OMT may be designed to fit in a lattice below one wavelength at the highest operating frequency, which is desirable for dual-polarized closely spaced array antennas in low and medium Earth orbit communication satellite systems. The simple mechanical design of the proposed OMT makes it particularly appealing for additive manufacturing techniques, as demonstrated with a variant of the design having folded single-mode waveguides, which preserves the RF properties of the original design.
Subject
Electrical and Electronic Engineering,Biochemistry,Instrumentation,Atomic and Molecular Physics, and Optics,Analytical Chemistry
Reference28 articles.
1. Fonseca, N.J.G., Angevain, J.-C., and Mangenot, C. (2011, January 18–21). Toward the terabit/s satellite: Antenna design trade-offs and analyses. Proceedings of the 33rd ESA Antenna Workshop, Noordwijk, The Netherlands.
2. Palacin, B., Fonseca, N.J., Romier, M., Contreres, R., Angevain, J.C., Toso, G., and Mangenot, C. (2017, January 19–24). Multibeam antennas for very high throughput satellites in Europe: Technologies and trends. Proceedings of the 2017 11th European Conference on Antennas and Propagation (EUCAP), Paris, France.
3. Recent patents on waveguide orthomode transducers;Fonseca;Recent Pat. Elect. Eng.,2010
4. A Broad-Band Dual-Mode Circular Waveguide Transducer;Tompkins;IRE Trans. Microw. Theory Technol.,1956
5. Steffe, W. (1995, January 18–23). A novel compact OMJ for Ku band Intelsat applications. Proceedings of the IEEE Antennas and Propagation Society International Symposium, Newport Beach, CA, USA.