|
| | | | |
| | | |
| Stat |
Members: 3645
Articles: 2'504'928
Articles rated: 2609
26 April 2024 |
|
| | | | |
|
Article overview
| |
|
|
Spillover and diffraction sidelobe contamination in a double-shielded experiment for mapping Galactic synchrotron emission | | C. Tello
; T. Villela
; G. F. Smoot
; M. Bersanelli
; N. Figueiredo
; G. De Amici
; M. Bensadoun
; C. A. Wuensche
; S. Torres
; | | Date: |
6 Jul 2000 | | Subject: | astro-ph | | Affiliation: | Instituto Nacional de Pesquisas Espaciais, Brazil Lawrence Berkeley National Laboratory, USA Universita di Milano, Italy Escola Federal de Engenharia de Itajuba, Brazil TRW, USA Newfield Wireless Inc, USA Centro Internacional de Fisica, Colombia | | Abstract: | We have analyzed observations from a radioastronomical experiment to survey the sky at decimetric wavelengths along with feed pattern measurements in order to account for the level of ground contamination entering the sidelobes. A major asset of the experiment is the use of a wire mesh fence around the rim-halo shielded antenna with the purpose of levelling out and reducing this source of stray radiation for zenith-centered 1-rpm circular scans. We investigate the shielding performance of the experiment by means of a geometric diffraction model in order to predict the level of the spillover and diffraction sidelobes in the direction of the ground. Using 408 MHz and 1465 MHz feed measurements, the model shows how a weakly-diffracting and unshielded antenna configuration becomes strongly-diffracting and double-shielded as far-field diffraction effects give way to near-field ones. Due to the asymmetric response of the feeds, the orientation of their radiation fields with respect to the secondary must be known a priori before comparing model predictions with observational data. By adjusting the attenuation coefficient of the wire mesh the model is able to reproduce the amount of differential ground pick-up observed during test measurements at 1465 MHz. | | Source: | arXiv, astro-ph/0007066 | | Services: | Forum | Review | PDF | Favorites | |
|
|
No review found.
Did you like this article?
Note: answers to reviews or questions about the article must be posted in the forum section.
Authors are not allowed to review their own article. They can use the forum section.
browser Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)
|
| |
|
|
|
|
News, job offers and information for researchers and scientists:
| |
REGISTER