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© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

W-Band radiometers using intermediate frequency down-conversion (super-heterodyne) and direct detection are compared. Both receivers consist of two W-band low noise amplifiers and an 80-to-101 GHz filter, which conforms to the reception frequency band, in the front-end module. The back-end module of the first receiver comprises a subharmonic mixer, intermediate frequency (IF) amplification and a square-law detector. For direct detection, a W-Band detector replaces the mixer and the intermediate frequency detection stages. The performance of the whole receivers has been simulated requiring special techniques, based on data from the experimental characterization of each subsystem. In the super-heterodyne implementation a local oscillator at 27.1 GHz (with 8 dBm) with a x3 frequency multiplier is used, exhibiting an overall conversion gain around 48 dB, a noise figure around 4 dB, and an effective bandwidth over 10 GHz. In the direct detection scheme, slightly better noise performance is obtained, with a wider bandwidth, around 20 GHz, since there is no IF bandwidth limitation (~15 GHz), and even using the same 80-to-101 GHz filter, the detector can operate through the whole W-band. Moreover, W-band detector has higher sensitivity than the IF detector, increasing slightly the gain. In both cases, the receiver performance is characterized when a broadband noise input signal is applied. The radiometer characteristics have been obtained working as a total power radiometer and as a Dicke radiometer when an optical chopper is used to modulate the incoming signal. Combining this particular super-heterodyne or direct detection topologies and total power or Dicke modes of operation, four different cases are compared and discussed, achieving similar sensitivities, but better performances in terms of equivalent bandwidth and noise for the direct detection radiometer. It should be noted that this conclusion comes from a particular set of components, which we could consider as typical, but we cannot exclude other conclusions for different components, particularly for different mixers and detectors.

Details

Title
Performance Assessment of W-Band Radiometers: Direct versus Heterodyne Detections
Author
Juan Pablo Pascual 1   VIAFID ORCID Logo  ; Aja, Beatriz 1   VIAFID ORCID Logo  ; Villa, Enrique 2   VIAFID ORCID Logo  ; Jose Vicente Terán 3 ; de la Fuente, Luisa 1   VIAFID ORCID Logo  ; Artal, Eduardo 1   VIAFID ORCID Logo 

 Departamento de Ingeniería de Comunicaciones, Universidad de Cantabria, Plaza de la Ciencia s/n, 39005 Santander, Spain; [email protected] (B.A.); [email protected] (L.d.l.F.); [email protected] (E.A.) 
 IACTEC, Instituto de Astrofísica de Canarias, 38205 La Laguna, Spain; [email protected] 
 ERZIA Technologies, 39012 Santander, Spain; [email protected] 
First page
2317
Publication year
2021
Publication date
2021
Publisher
MDPI AG
e-ISSN
20799292
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2576497187
Copyright
© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.