English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

SARAS is an ongoing experiment aiming to detect the redshifted global 21-cmsignal expected from Cosmic Dawn (CD) and the Epoch of Reionization (EoR).Standard cosmological models predict the signal to be present in the redshiftrange $z \sim $6--35, corresponding to a frequency range 40--200~MHz, as aspectral distortion of amplitude 20--200~mK in the 3~K cosmic microwavebackground. Since the signal might span multiple octaves in frequency, and thisfrequency range is dominated by strong terrestrial Radio Frequency Interference(RFI) and astrophysical foregrounds of Galactic and Extragalactic origin thatare several orders of magnitude greater in brightness temperature, design of aradiometer for measurement of this faint signal is a challenging task. It iscritical that the instrumental systematics do not result in additive ormultiplicative confusing spectral structures in the measured sky spectrum andthus preclude detection of the weak 21-cm signal. Here we present the systemdesign of the SARAS~3 version of the receiver. New features in the evolveddesign include Dicke switching, double differencing and optical isolation forimproved accuracy in calibration and rejection of additive and multiplicativesystematics. We derive and present the measurement equations for the SARAS~3receiver configuration and calibration scheme, and provide results oflaboratory tests performed using various precision terminations that qualifythe performance of the radiometer receiver for the science goal.

SARAS 3 CD/EoR Radiometer: Design and Performance of the Receiver