Platelet Orthomode Transducer for &lt;formula formulatype="inline"&gt; &lt;tex Notation="TeX"&gt;$Q$&lt;/tex&gt;&lt;/formula&gt;-Band Correlation Polarimeter Clusters

Virone, G.; Peverini, O. A.; Lumia, Mauro; Addamo, Giuseppe; Tascone, R.

doi:10.1109/tmtt.2014.2325793

Cited by 22 publications

(8 citation statements)

References 27 publications

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“…These will contaminate polarization measurements only through any leakage from total intensity to polarization that could be present in our receivers and that will be caused mainly by asymmetries in the polarizer-OMT system. Considering that our current estimates from OMT laboratory measurements [46] indicate a leakage of the order of ∼ 0.01% this effect is likely to be negligible. We are currently working on a simulation framework that will model the expected fluctuations in the atmosphere brightness temperature and their effect of the sky polarization measurement and will allow us to quantify the impact of this systematic effect.…”

Section: Lspe-strip Noise Estimationmentioning

confidence: 77%

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The large scale polarization explorer (LSPE) for CMB measurements: performance forecast

Addamo

Ade

Baccigalupi

et al. 2021

J. Cosmol. Astropart. Phys.

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The measurement of the polarization of the Cosmic Microwave Background (CMB) radiation is one of the current frontiers in cosmology. In particular, the detection of the primordial divergence-free component of the polarization field, the B-mode, could reveal the presence of gravitational waves in the early Universe. The detection of such a component is at the moment the most promising technique to probe the inflationary theory describing the very early evolution of the Universe. We present the updated performance forecast of the Large Scale Polarization Explorer (LSPE), a program dedicated to the measurement of the CMB polarization. LSPE is composed of two instruments: LSPE-Strip, a radiometer-based telescope on the ground in Tenerife-Teide observatory, and LSPE-SWIPE (Short-Wavelength Instrument for the Polarization Explorer) a bolometer-based instrument designed to fly on a winter arctic stratospheric long-duration balloon. The program is among the few dedicated to observation of the Northern Hemisphere, while most of the international effort is focused into ground-based observation in the Southern Hemisphere. Measurements are currently scheduled in Winter 2022/23 for LSPE-SWIPE, with a flight duration up to 15 days, and in Summer 2022 with two years observations for LSPE-Strip. We describe the main features of the two instruments, identifying the most critical aspects of the design, in terms of impact on the performance forecast. We estimate the expected sensitivity of each instrument and propagate their combined observing power to the sensitivity to cosmological parameters, including the effect of scanning strategy, component separation, residual foregrounds and partial sky coverage. We also set requirements on the control of the most critical systematic effects and describe techniques to mitigate their impact. LSPE will reach a sensitivity in tensor-to-scalar ratio of σ r < 0.01, set an upper limit r < 0.015 at 95% confidence level, and improve constraints on other cosmological parameters.

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Section: Lspe-strip Noise Estimationmentioning

confidence: 77%

“…In Q-band we convert linear to circular polarization using a groove polarizer [45] connected to a platelet OMT [46]. In figure 8 we show the complete set of Q-band polarizers (left panel) and OMTs (right panel) implemented in the Strip focal plane.…”

Section: Instrument and Cryogenicsmentioning

confidence: 99%

The large scale polarization explorer (LSPE) for CMB measurements: performance forecast

Addamo

Ade

Baccigalupi

et al. 2021

J. Cosmol. Astropart. Phys.

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“…Each array element in the focal plane [16] includes a corrugated feed horn, followed by a dual-circular polarization chain (a groove polarizer [17,18] coupled to an orthomode transducer [19] in the Q-band; and a septum polarizer in the W-band), feeding the polarimetric module based on High Electron Mobility Transistor low noise amplifiers. The signal is then amplified and digitized in the warm electronics unit on board the telescope structure.…”

Section: The Focal Plane Arraysmentioning

confidence: 99%

The LSPE-Strip feed horn array

et al. 2022

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In this paper we discuss the design, manufacturing and characterization of the feed horn array of the Strip instrument of the Large Scale Polarization Explorer (LSPE) experiment. Strip is a microwave telescope, operating in the Q- and W-band, for the observation of the polarized emissions from the sky in a large fraction (about 37%) of the Northern hemisphere with sub-degree angular resolution. The Strip focal plane is populated by forty-nine Q-band and six W-band corrugated horns, each feeding a cryogenically cooled polarimeter for the detection of the Stokes Q and U components of the polarized signal from the sky. The Q-band channel is designed to accurately monitor Galactic polarized synchrotron emission, while the combination of Q- and W-band will allow the study of atmospheric effects at the observation site, the Observatorio del Teide, in Tenerife. In this paper we focus on the development of the Strip corrugated feed horns, including design requirements, engineering and manufacturing, as well as detailed characterization and performance verification.

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“…Since the latter directions are rotated by 45 • w.r.t. the inductive (L // x) and capacitive (C // ŷ) principal directions of the polarizer [5], the platelet Ortho-Mode Transducer (OMT) described in [6] is rotated by 45 • w.r.t. the principal axes L and C of the polarizer.…”

Section: The Lspe-strip Instrumentmentioning

confidence: 99%

Q-band polarizers for the LSPE-Strip correlation radiometric instrument

Peverini

Lumia²,

Farooqui³

et al. 2022

J. Inst.

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This paper reports the design, manufacturing and testing of the cluster of polarizers developed for the LSPE-Strip correlation receiver array working in the Q band (39–48 GHz). Since the LSPE experiment targets the measurement of the very faint B-mode component of the Cosmic Microwave Background, the electromagnetic design of the polarizers was conceived in view of minimizing the measurement uncertainties introduced by the polarizers in the LSPE-Strip dual-circular-polarization correlation receiving chain. To this end, the main figures-of-merit of the LSPE-Strip polarizers were derived in terms of the Mueller sub-matrices relating the relevant input and output Stokes parameters. As a result, a dual-ridge layout, in which stepped-ridge discontinuities are interleaved with grooved cavities, was selected. The heights of both the stepped discontinuities and the grooved cavities were considered as design degrees of freedom in order to minimize the differential phase-error between the two principal polarizations of the polarizer w.r.t. the ideal 90-deg value. The latter condition is the one required for converting the incoming circular polarizations into two linearly polarized ones. The polarizer design allows for a complete manufacturing route (mechanical layout, machining process and assembling) exhibiting high accuracy (< 10 μm) for all the units. As a consequence, the measured performance of the whole polarizer cluster is in tight agreement with predictions. Notably, the in-band mean value of the spurious conversion from the total intensity I to the two linearly polarized Stokes parameters Q and U introduced by the polarizers is smaller than -28 dB (mean value of fifty-one polarizers) with a standard deviation less than 1 dB.

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Platelet Orthomode Transducer for <formula formulatype="inline"> <tex Notation="TeX">$Q$</tex></formula>-Band Correlation Polarimeter Clusters

Cited by 22 publications

References 27 publications

The large scale polarization explorer (LSPE) for CMB measurements: performance forecast

The large scale polarization explorer (LSPE) for CMB measurements: performance forecast

The LSPE-Strip feed horn array

Q-band polarizers for the LSPE-Strip correlation radiometric instrument

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