A metamaterial with applications in broad band antennas used in radio astronomy and satellite communications

Abstract

Electromagnetic metamaterials at microwave frequencies are well established in industry and research. Recent work has shown how a specific kind of metallic metamaterial can contribute towards improving the performance of the feedhorn antennas used in radio astronomy and satellite telecommunications. In this article, we discuss an innovative type of meta-ring of remarkable manufacturability, able to improve the state of the art in these fields. A pioneering meta-horn antenna formed of meta-rings is then fabricated and characterized in the laboratory. It shows an excellent feature on an octave bandwidth, especially in terms of cross-polarization, a key figure of merit in both radio astronomy and telecommunications, and also side-lobe level, return-loss and gain.

A microwave blackbody target for cosmic microwave background spectral measurements in the 10–20 GHz range

“…The RF verification of the 4KCL entailed the measurement of the 4KCL specular and diffusive reflectivity (spillover). We reported values of specular RL much better than the required −30 dB over the frequency range between 8-24 GHz, and also better than the −40 dB design goal for most of the TMS band (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The reflectivity of the 4KCL was also characterised using the TMS nominal metamaterial feedhorn to simulate a similar experimental condition as that of the TMS operation, obtaining even better results for the RL.…”

“…This is a stringent requirement and can only be met in the majority of the band. Near the cutoff frequency (< 10.5 GHz) the 𝑅𝐿 feed > −30 dB, and it is addressed in [19].…”

“…During the project, we updated the return loss requirement to −30 dB for the horn, in order to achieve a better matching. These demands are met with a novel design based on metamaterials, fully described in [19]. The manufactured horn presents a total length of 240 mm, with an aperture diameter of 103 mm, external diameter of 180 mm, and a 20 mm-diameter feedhorn mouth.…”

“…RF and thermal verification. In [19], the radiation properties of the TMS feedhorn are reported, including measurements of the return losses. We performed a few RF verification tests at the IAC facilities to cross check the results obtained.…”

“…• 𝑧 = 68 mm is the distance at which the base of the load shall be located, taking into account the maximum room restriction specified in section 3. comparison between simulation results (solid lines obtained with CST Studio and SRSR software and the return loss measurements (dashed lines) reported in [19] and those performed in the IAC facilities. Both results are consistent with each other and with the simulations.…”