Abstract: A single- or dual-circularly polarized earth station antenna is converted into a single- or dual-linearly polarized earth station antenna for accessing linearly polarized satellites. In a first embodiment, a free-space meander line polarizer providing a 90.degree. differential phase shift between two orthogonal polarizations is disposed in front of the earth station antenna feed system. In a second embodiment, a power dividing (transmit) or power combining (receive) network operates in conjunction with differential phase shift circuits to achieve the polarization conversion.

Abstract: A thermionic energy conversion method and apparatus is disclosed that eliminates or substantially reduces deficiencies caused by space charge or thermal radiation losses from the emitter to the collector. The method and apparatus uses an acceleration electrode having an aperture and disposed in the space between the emitter and collector. A high positive voltage is applied to the acceleration electrode to generate a positive electrostatic field. The shape of the facing surfaces of the emitter and collector and the shape of the acceleration electrode shape the electrostatic field to cause boiled-off electrons from the emitter to be accelerated and converged so that they all pass through the aperture without impinging on the acceleration electrode.

Abstract: A push-pull microwave amplifier in which an input signal is split into two ransmission paths in a manner which simulates the behavior of a center-tapped transformer over a broad frequency range. The input signal is first divided into two identical paths and then passed down first and second transmission line segments in the two paths bi-directionally. One of the transmission line segments is terminated in an open circuit and the other in a short circuit so that the reflected signals have the opposite polarities. By making the transmission line segments of equal length, the opposite polarity signals emerge from the transmission line segments at the same time. The signals are then amplified and then passed again bi-directionally along third and fourth transmission line segments terminated in short and open circuits so as to re-convert the signals to the same polarity. The signals are then summed to produce the composite amplified output signal.

Abstract: A nearly instantaneous companding processor uses variable precision block quantization for reducing the digital transmission rate of speech signals while at the same time maintaining a high quality signal in a digital communication system. The variable number of bits which are used to encode each sample is controlled as a function of the maximum sample magnitude in a block of N samples. This technique takes advantage of the amplitude probability density function of a speech signal to thereby reduce the quantizing noise without increasing the transmission rate.