Super-Gaussian apodization in ground based telescopes for high contrast coronagraph imaging

We introduce the use of Super-Gaussian apodizing functions in the telescope pupil plane and/or the coronagraph Lyot plane to improve the imaging contrast in ground-based coronagraphs. We describe the properties of the Super-Gaussian function, we estimate its second-order moment in the pupil and Fourier planes and we check it as an apodizing function. We then use Super-Gaussian function to apodize the telescope pupil, the coronagraph Lyot plane or both of them. The result is that a proper apodizing masks combination can reduce the exoplanet detection distance up to a 45% with respect to the classic Lyot coronagraph, for moderately aberrated wavefronts. Compared to the prolate spheroidal function the Super-Gaussian apodizing function allows the planet light up to 3 times brighter. An extra help to increase the extinction rate is to perform a frame selection (Lucky Imaging technique). We show that a selection of the 10% best frames will reduce up to a 20% the detection angular distance when using the classic Lyot coronagraph but that the reduction is only around the 5% when using an apodized coronagraph

Design methodology and performance analysis of a wideband 90º phase switch for radiometer applications

This paper presents the analysis, design, and characterization of a wideband 90º phase switch in Ka-band. The phase switch is based on two microstrip bandpass filters in which the commutation is performed by a novel single-pole double-throw (SPDT) switch. The analysis of π-network bandpass filters is provided, obtaining the phase difference and amplitude imbalance between filters and their scattering parameters; tested results show an average phase difference of 88.9º ± 5º and an amplitude imbalance of 0.15 dB from 24 to 37 GHz. The new broadband SPDT switch is based on a coplanar waveguide-to-slotline-to-microstrip structure, which enables a full planar integration with shifting branches. PIN diodes are used to perform the switching between outputs. The SPDT shows isolation better than 19 dB, insertion loss of around 1.8 dB, and return loss better than 15 dB. The full integration of the phase switch achieves a return loss better than 11 dB and insertion loss of around 4 dB over the band 26–36 GHz, with an average phase difference of 87.1º ± 4º and an average amplitude imbalance of 0.3 dB. It provides an excellent performance for this frequency range, suitable for radio-astronomy receivers.The authors would like to thank the Spanish Ministry for Science and Innovation for the financial support provided under the Project No. AYA2010–21766-C03–03 and the CONSOLIDER-INGENIO 2010 programme under Reference No. CSD2010–00064

Q-band 4-state phase shifter in planar technology: Circuit design and performance analysis

A 30% bandwidth phase shifter with four phase states is designed to be integrated in a radio astronomy receiver. The circuit has two 90° out-of-phase microwave phase-shifting branches which are combined by Wilkinson power dividers. Each branch is composed of a 180° phase shifter and a band-pass filter. The 180° phase shifter is made of cascaded hybrid rings with microwave PIN diodes as switching devices. The 90° phase shift is achieved with the two band-pass filters. Experimental characterization has shown significant results, with average phase shift values of -90.7°, -181.7°, and 88.5° within the operation band, 35–47 GHz, and mean insertion loss of 7.4 dB. The performance of its integration in a polarimetric receiver for radio astronomy is analyzed, which validates the use of the presented phase shifter in such type of receiver.This work was supported by the Ministerio de Economía y Competitividad, Spain, under the CONSOLIDER-INGENIO 2010 programme under the Reference No. CSD2010-00064

The importance of social relationships and loneliness: An inclusive research project in Spain

This article presents the results of a project carried out by a group of researchers with and without intellectual disabilities on the importance of social relationships and loneliness. We wanted to find out about the experience of loneliness in young people with and without intellectual disabilities and know whether this was an important issue for them too. We interviewed a total of 23 young people during our research which was developed over more than a year and a half. This article has been organised into three parts. In the first part, the two academic researchers outline the concept of inclusive research highlighting the value of recognising and making the experiences of people with intellectual disabilities visible. Following this, the four authors describe how the research group was formed and the methodological decisions that were made. Finally, we report the results of the research and the main conclusions. The young people with and without disabilities we interviewed told us that nobody wants to feel lonely. We believe that it is important for other researchers at the university to recognise our work and be encouraged to implement inclusive research processes.This work was supported by the Ministry of the Economy and Competitiveness (EDU2015-68617-C4-4-R). Principal researcher: Teresa Susinos Rad

Híbrido 180º de banda ancha en tecnología Microstrip a 41 GHz

A broadband modified rat-race hybrid with around 30% bandwidth is presented in this paper. The hybrid was developed from 35 to 47 GHz bandwidth (centre frequency 41 GHz) using microstrip technology on Alumina substrate. The design uses CPWG-Microstrip transitions to measure the response of the circuit in a coplanar probes station. The measurements over the frequency bandwidth show a maximum amplitude imbalance of 0.5 dB, the phase variation is ± 5º, the isolation is better than 20 dB and the return loss is greater than 10 dB. Moreover, the circuit is planar and consists of a single layer, without requirements of metallic holes and bonding wires, so it is also a low-cost circuit

Híbrido 180º de banda ancha en tecnología microstrip a 31 GHz

A broadband modified rat-race hybrid with around 35% bandwidth is presented in this paper. This hybrid was developed from 26 to 36 GHz bandwidth (centre frequency 31 GHz) using microstrip technology on Alumina substrate. The design uses CPWG-Microstrip transitions to measure the response of the circuit in a coplanar probes station. Measurements across the frequency bandwidth show a maximum amplitude imbalance of 0.5 dB, the phase variation is ± 5º, the isolation is better than 25 dB and the return loss is greater than 10 dB. Moreover, the circuit is planar, easy to design and consists of a single layer, without requirements of metallic holes and bonding wires, so it is also a low-cost circuit

Experimental validation of Lyot stop apodization in ground-based coronagraphy

ABSTRACT We show that the use of apodizing functions at the coronagraph Lyot plane may be useful for improving the image contrast of ground-based coronagraphs. An experimental set-up consisting of a tip–tilt mirror, a coronagraph and a low-noiseEMCCDcamerawas implemented at theWilliam Herschel Telescope. Images were taken in the I band, which meant that the D/r0 value was around 10. Experimental results confirm that, for moderately aberrated wavefronts, our instrument works as theoretically expected, and that the contrast value attained is high enough to provide direct detection of faint companions.This research was supported by the Ministerio de Economía y Competitividad under project FIS2012-31079 and the Fundación Séneca of Murcia under projects 15419/PI/10 and 15345/PI/10

Coronagraphs adapted to atmosphere conditions

In this paper we show new ways to improve the performance of ground-based coronagraphy. We introduce adaptive coronagraphic masks whose profile is a binary version of the instantaneous atmospherically degraded star image. We also propose the hyper-Gaussian profile masks obtained by averaging adaptive masks. In addition, adaptive Lyot stops and hyper-Gaussian Lyot stops are analyzed. Computer simulations show that all these masks outperform the circular hard-edged mask and that a proper mask and stop combination significantly reduces the angular separation at which a faint companion can be detected

The thirty gigahertz instrument receiver for the QUIJOTE experiment: preliminary polarization measurements and systematic-error analysis

This paper presents preliminary polarization measurements and systematic-error characterization of the Thirty Gigahertz Instrument receiver developed for the QUIJOTE experiment. The instrument has been designed to measure the polarization of Cosmic Microwave Background radiation from the sky, obtaining the Q, U, and I Stokes parameters of the incoming signal simultaneously. Two kinds of linearly polarized input signals have been used as excitations in the polarimeter measurement tests in the laboratory; these show consistent results in terms of the Stokes parameters obtained. A measurement-based systematic-error characterization technique has been used in order to determine the possible sources of instrumental errors and to assist in the polarimeter calibration process.The authors would like to thank Spanish Ministry for Economy and Competitiveness for the financial support provided under the CONSOLIDER-INGENIO 2010 program under the reference CSD2010-00064 and the project under reference AYA2012-39475-C02-01

A new tool based on artificial intelligence and GIS for preventive conservation of heritage buildings

This paper describes a new predictive model for preventive conservation of buildings. It allows for multiscenarios of several hazards, assessments of environmental risks, and the use level of buildings together with cultural val-ues of monuments. This modeling approach is based on fuzzy logic and geographic information system available to organizations dedicated to the restoration and rehabilitation in Spain. This system has a transversal development that includes urban, architectural, cultural heritage value, and the analysis of environmental and sociodemographic situations around the monuments. This new tool allows for decision making based on scientific criteria and minimizes risklosses of cultural asset