A wideband resistive beam-splitter screen

Mahesh, Nivedita ; Subrahmanyan, Ravi ; Udaya Shankar, N. ; Raghunathan, Agaram (2015) A wideband resistive beam-splitter screen IEEE Transactions on Antennas and Propagation, 63 (11). pp. 4835-4847. ISSN 0018-926X

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Official URL: https://ieeexplore.ieee.org/document/7265020/

Related URL: http://dx.doi.org/10.1109/TAP.2015.2478443


We present the design, construction and measurements of the electromagnetic performance of a wideband space beam splitter. The beam splitter is a sheet in free space that is designed to divide incident radiation into reflected and transmitted components for interferometer measurement of spectral features in the mean cosmic radio background. Analysis of a two-element interferometer configuration with a vertical beam splitter between a pair of antennas leads to the requirement that the beam splitter be a resistive sheet with sheet resistance ηo/2, where ηo is the impedance of free space. The transmission and reflection properties of such a sheet are computed for normal and oblique incidences and for orthogonal polarizations of the incident electric field. We have constructed such an electromagnetic beam splitter as a square-soldered grid of resistors of value 180 Ohms (approximately ηo/2) and a grid size of 0.1 m. We measured the reflection and transmission coefficients over a wide frequency range between 50 and 250 MHz in which the wavelength well exceeds the mesh size. Measurements of the coefficients for voltage transmission and reflection agree to within 5% with physical optics modeling of the wave propagation, which takes into account edge diffraction.

Item Type:Article
Source:Copyright of this article belongs to Institute of Electrical and Electronic Engineers.
Keywords:Physical Optics; Antenna Measurements; Radio Astronomy; Maxwell Equations
ID Code:114392
Deposited On:22 May 2018 06:42
Last Modified:22 May 2018 06:42

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