Abstract: An antenna assembly may be positioned within a wellbore in a subterranean formation. The antenna assembly includes a tubular antenna element to be positioned within the wellbore, and an RF coaxial transmission line to be positioned within the tubular antenna element. The RF coaxial transmission line includes a series of coaxial sections coupled together in end-to-end relation, each coaxial section including an inner conductor, an outer conductor surrounding the inner conductor, and a dielectric therebetween. Each of the outer conductors has opposing threaded ends defining overlapping mechanical threaded joints with adjacent outer conductors.

Abstract: An antenna assembly may be positioned within a wellbore in a subterranean formation. The antenna assembly includes a tubular antenna element to be positioned within the wellbore, and an RF coaxial transmission line to be positioned within the tubular antenna element. The RF coaxial transmission line includes a series of coaxial sections coupled together in end-to-end relation, each coaxial section including an inner conductor, an outer conductor surrounding the inner conductor, and a dielectric therebetween. Each of the outer conductors has opposing threaded ends defining overlapping mechanical threaded joints with adjacent outer conductors.

Abstract: An antenna assembly may be positioned within a wellbore in a subterranean formation. The antenna assembly includes a tubular antenna element to be positioned within the wellbore, and an RF coaxial transmission line to be positioned within the tubular antenna element. The RF coaxial transmission line includes a series of coaxial sections coupled together in end-to-end relation, each coaxial section including an inner conductor, an outer conductor surrounding the inner conductor, and a dielectric therebetween. Each of the outer conductors has opposing threaded ends defining overlapping mechanical threaded joints with adjacent outer conductors.

Abstract: An amplifier has at least several stages activated only to one of two bi-level states controlled in response to the value of an input source exceeding a threshold for each stage. Each stage has a different threshold. The thresholds and source are arranged so that the stages change between the bi-level states as the value of the source changes relative to the thresholds of the different stages. Bi-level outputs of the stages are summed together. The values of the thresholds are continuously varied by a small amount relative to a predetermined maximum value for the source in response to a noise source that is independent of the signal source. A power supply for the stages includes an AC-DC converter having plural primary windings and several secondary windings, one for each of the stages. The windings are coupled together so that at all times loading of the primary windings by the secondary windings as a result of activation of the output stages is approximately equal.

Abstract: A power amplifier for a plate load of an AM, RF transmitter includes plural switching stages each powered by a DC source. Each stage is switched from non-sourced to saturation in response to the amplitude of an analog source exceeding a threshold amplitude for the stage; each stage has a different threshold. The thresholds and analog source are arranged so that responses derived between output terminals of the stages change between zero and predetermined amplitudes as the source amplitude changes relative to the thresholds of the different stages. The responses of the different stages are summed. A triangular wave having a small constant maximum amplitude relative to the analog source maximum value effectively changes the threshold of each stage.