Abstract: A loop antenna which is electrically small relative to a wavelength of a signal which it is designed to receive. The antenna is an electrically small, low profile, band switchable antenna which can be mounted on a metallic surface such as a truck or railway car rooftop and can be used to communicate with earth satellites. The antenna is polarized such that the plane containing the electric field is horizontal. Alternatively, the antenna can receive circularly polarized signals.

Abstract: A bias circuit for a pair of field effect transistor (FET) stages comprising a circuit for AC coupling a signal amplified by a first stage to the input of a second stage, a power source for supplying DC operating current to both of the stages in series, a circuit for sensing current drawn by the second stage and in response thereto for controlling bias of the first stage, and a circuit for blocking AC signals amplified by the first stage from being passed via a DC operating current path to the second stage, whereby the same DC operating current is passed through both first and second stages and is blocked from passing through the AC coupling circuit.