New technologies for the Tenerife Microwave Spectrometer and current status

Alonso-Arias, P.; Rubiño-Martín, J. A.; Hoyland, R. J.; Aguiar-González, M.; de-Miguel-Hernández, Javier; Génova-Santos, R. T.; Gómez-Reñasco, M. F.; Guidi, F.; Fernández-Torreiro, M.; Fuerte-Rodríguez, Pablo A.; Hernández-Monteagudo, C.; López-Caraballo, C. H.; Perez-de-Taoro, Angeles; Peel, M.; Rebolo, R.; Zamora-Jimenez, Antonio; González-Carretero, Eduardo D.; Colodro-Conde, Carlos; Pérez-Lemus, Cristina; Toledo-Moreo, R.; Cuttaia, F.; Terenzi, L.; Franceschet, C.; Realini, S.

doi:10.1117/12.2561353

Cited by 4 publications

(6 citation statements)

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“…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.…”

Section: Discussionmentioning

confidence: 80%

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

Alonso-Arias,

Cuttaia,

Terenzi

et al. 2024

J. Inst.

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The Tenerife Microwave Spectrometer (TMS) is a ground-based radio-spectrometer that will take absolute measurements of the sky between 10–20 GHz. To ensure the sensitivity and immunity to systematic errors of these measurements, TMS includes an internal calibration system optimised for the TMS band, and cooled down to 4 K. It consists of an Aluminium core, composed of a baseplate and a bed of pyramidal elements coated with an absorber material and a metallic shield. The absorber coating is made of a commercial resin ECCOSORB CR/MF 117. To achieve the high stability (± 1 mK/h), temperature homogeneity (thermal gradients ΔT ≤ 25 mK), and emissivity (e ≥ 0.999) requirements of the reference unit, careful consideration has been given to the RF and thermal properties of the materials, as well as their geometry. In summary, this paper presents a comprehensive account of the design, characterisation, and test results of the TMS reference system.

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Section: Discussionmentioning

confidence: 80%

“…100 min. Reproduced with permission from[15]. Right: CAD 3D representation of the TMS cryostat including the window, the sky feedhorn and the reference feedhorn mated to the 4KCL.…”

mentioning

confidence: 99%

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

Alonso-Arias,

Cuttaia,

Terenzi

et al. 2024

J. Inst.

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“…We continue with the in-depth study of the main beam and far sidelobes, with special emphasis on frequency variation. The TMS instrument is a spectrometer that will continuously acquire the sky spectrum and compare it to the spectrum of a cold calibrator [10,11]. While the spectrum of the calibrator is known and stable over the TMS frequency range, it is necessary to have perfectly defined and characterised the and the near-optimal configuration (green colour) achieved for the TMS optical system after appropriate iterations.…”

Section: The Tms Optical Performancementioning

confidence: 99%

The optical system of the Tenerife Microwave Spectrometer: a window for observing the 10-20 GHz sky spectra

Alonso-Arias¹,

Fuerte-Rodriguez²,

Hoyland³

et al. 2021

Preprint

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The TMS optical system is based on a decentered dual-reflector system in a Gregorian configuration to observe with an angular resolution of less than 2°. The primary goal of the present study is to evaluate the final design and verify that it satisfies the design requirements. We aim for low cross-polarization (−30 dB), low sidelobe (−25 dB) levels, and a stable beam in terms of shape (low ellipticity) and size over a full octave bandwidth (10-20 GHz). We performed both raytracing and full-wave simulations using the CST Studio software in order to investigate the system behaviour. We gave special attention to the beam frequency variation and polarization leakage. We have characterized the effects on the radiation pattern produced by the cryostat window. We present the final design of the TMS optical system, as well as a complete study of the system's performance in terms of cross-polarization, sidelobes, ellipticity and beamwidth. We discuss the effects of sidelobes and study the need for a baffle.

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“…Common concerns regarding calibration and characterization of systematic errors due to optical systems in CMB experiments include: the control of sidelobes; the discrimination of orthogonal polarizations; and the control of the beam ellipticity and size variation throughout the operational bandwidth. These concerns affect the TMS experiment and its technical requirements in the same way: 1) the required level of sensitivity [10] imposes an extremely low system temperature and, to ensure that no unwanted sources in the sky add to this temperature, we require a maximum sidelobe level of −25 dB; 2) the pseudo-correlation architecture of the TMS radiometer [11] takes advantage of the use of both orthogonal polarizations to double its reception capacity, for which we require excellent cross-polarization discrimination, lower than −30 dB; and 3) although it was not the original goal, the TMS has polarimetric capabilities [10,11], and therefore, stabilizing the beam ellipticity around 4% throughout the band is key to reduce errors when reconstructing the linear spectra. To meet all of these requirements, the TMS relies on a Gregorian optical configuration, with a 1.5 m parabolic primary mirror, and a 0.6 m elliptical secondary mirror.…”

Section: Jinst 16 P12037mentioning

confidence: 99%

“…In addition, beam size and shape must be analytically comparable over the band, so we are able to reconstruct the linear polarization spectra (Q and U Stokes parameters). Table 1 summarizes the basic optical characteristics of the TMS (see [10,11] for more information about the instrument technical requirements and design).…”

Section: General Layout Of the Optical Systemmentioning

confidence: 99%

The optical system of the Tenerife Microwave Spectrometer: a window for observing the 10–20 GHz sky spectra

et al. 2021

View full text Add to dashboard Cite

The TMS optical system is based on a decentered dual-reflector system in a Gregorian configuration to observe with an angular resolution of less than 2°. The primary goal of the present study is to evaluate the final design and verify that it satisfies the design requirements. We aim for low cross-polarization (-30 dB), low sidelobe (-25 dB) levels, and a stable beam in terms of shape (low ellipticity) and size over a full octave bandwidth (10–20 GHz). We performed both ray-tracing and full-wave simulations using the CST Studio software in order to investigate the system behaviour. We gave special attention to the beam frequency variation and polarization leakage. We have characterized the effects on the radiation pattern produced by the cryostat window. We present the final design of the TMS optical system, as well as a complete study of the system's performance in terms of cross-polarization, sidelobes, ellipticity and beamwidth. We discuss the effects of sidelobes and study the need for a baffle.

show abstract

New technologies for the Tenerife Microwave Spectrometer and current status

Cited by 4 publications

References 0 publications

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

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

The optical system of the Tenerife Microwave Spectrometer: a window for observing the 10-20 GHz sky spectra

The optical system of the Tenerife Microwave Spectrometer: a window for observing the 10–20 GHz sky spectra

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