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The Square Kilometre Array (SKA) radio-telescope is projected to become a reality in 2020. Nowadays, many research groups are investigating the technologies that will be necessary to build this enormous instrument. The reference design of the SKA establishes that the mid-frequency range (from 300 MHz to 1 GHz) will be covered by planar aperture arrays. FIDA3 is an active array prototype formed by...
Differential amplifiers have been proposed as an efficient solution for the planar aperture arrays in the low frequency band of the SKA project. The characterization of this type of devices is not the typical one, and they need of some specific techniques. On the other hand, the use of antennas matched to a non-50 Omega impedance requires of source-pull techniques for an accurate measurement. In this...
A semi-lumped balun transformer for UHF and ultrawideband (UWB) dipole antennas is presented in this paper. The proposed structure is based on two asymmetric filters that also transform the variable antenna impedance into the desired source impedance. These asymmetric filters make use of a binomial impedance transformer in each filter section. The asymmetric filters (one low pass filter, LPF, and...
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