Abstract: A coaxial inductive radio cable for use as an antenna in which both the inner and outer conductor are wound in spirals having the same spiral winding orientation and the pitch of the outer spiral conductor is two or three times the pitch of the inner spiral conductor.

Abstract: A graded leaky coaxial cable comprised of a center conductor, a dielectric surrounding the center conductor, and a braided conductive shield woven around and surrounding the dielectric. The shield has progressively fewer ends along its length, whereby progressively larger non-conducting gaps are formed separated by closely woven groups of carriers, thus facilitating controlled penetration of a radial frequency field through the shield.

Abstract: Radiating coaxial electric cable comprises a conductor core (1), a cellular dielectric (2), an outer conductor (3) having apertures for the passage of electromagnetic radiation, and an outer insulating sheath (4). The radiation-passing apertures consist of successive series of holes (6) aligned according to a helix segment pattern.

Abstract: A sensor for use in a leaky cable intrusion system which is comprised of a pair of parallel buried coaxial cables, each of which has a velocity of propagation factor different from the other. This results in different sensitivity characteristics with length, resulting in a combined sensitivity which has markedly reduced amplitude variation over cables having similar velocities of propagation. It also makes feasible a system having ungraded cables in which the position of intrusion in the field set up by the sensor can be determined.

Abstract: A leaky coaxial cable for use as a sensor in a buried or other medium, which has a conductor located parallel to, and in proximity with the shield along the cable, but insulated therefrom. Preferably the two wire transmission line formed by the external conductor and the shield is terminated with an impedance matching the characteristic impedance of the transmission line (for minimum reflections). The external conductor can be oriented to cause the field in a given direction (e.g. above the surface of the burial medium) to be compensated for field variations caused by variations in the burial medium.

Abstract: A method of producing a leakage graded coaxial cable having a braided shield, in which ends of the shield wire are dropped as braiding progresses. Gaps in the shield having progressively increasing size are produced through which the radio frequency field leakage occurs, which facilitates providing a constant radio frequency field around the cable. The cable is coated with a jell flooding agent prior to extrusion of its protection jacket, which fills the interstices and gaps of the shield, and solidifies to a waxy, semi-resilient consistency. The resulting cable can be coiled and flexed, maintaining its shield reliability, and rejects water and fluids in case pinholes in the jacket occur.

Abstract: A method of manufacturing leaky coaxial cable by winding conductive tapes around a core to provide apertures of a certain shape, number and density. By varying the width of one or both tapes the aperture distribution is varied thereby altering the coupling of the cable when used in a detection system. A graded cable showing such varying coupling can be used to compensate for cable attenuation losses and other variables.

Abstract: High-frequency radio waves are transmitted through a coaxial cable having apertures spaced at a distance considerably larger than the wavelength of the signals; the apertures are feed points for surface waves on the cable.

Abstract: An optimum coupling unit for joining adjacent sections of coaxial cable and a coupled radiating antenna includes different diameters of the dielectric material, different diameters of central conductor and different values of the dielectric constant material in order to provide impedance matching at any section of the coupler including the coupled antenna to the impedance of the coaxial cable. The coupling unit is combined with the antenna as an integral unit. The antenna may be a dipole whose elements are coupled to the coupling unit through a parallel plate transmission line. Impedance matches are maintained at each coupling point.

Abstract: The subject invention is directed to a radiating cable comprising at least one center conductor, a dielectric core surrounding said conductor and a plurality of radiating sheaths disposed in coaxial relationship to said at least one center conductor along the length of said dielectric core. The cable design minimizes attenuation of the internal TEM signal and reduces the environmental sensitivity of the cable.

Abstract: An intrusion detection system includes a transmitter of wave energy at one end of a transmission line or coaxial cable, for example, and a receiver connected directly to the transmission line or a cable at the other end together with a series or discrete antennas uniformly spaced along the transmission line and relatively loosely coupled thereto. The coupling between the antennas and the transmission line or coaxial cable is determined to be of an optimum value and in such a system the sensitivity to an intrusion is the same along the length of the coaxial cable or transmission line for the same distance from the transmission line.

Abstract: A physical deterrent barrier is utilized as an integral part of an intruder detection sensor that provides surveillance of intrusions in the air space over the barrier. The sensor is a corner reflecting antenna that is coextensive with and mounts on the top of the barrier and is integrated into a barbed wire topped chain link fence by arranging appropriately spaced parallel strands of barbed wire into a V configuration so as to effect an electrical corner reflector at the system operating frequency.

Abstract: The outer conductor of a high frequency electric cable of the kind employed as a stationary elongate element for transmitting high frequency signals to, or receiving high frequency signals from a receiving or transmitting device carried by a mobile body, has extending along its length at least one row of mutually spaced apertures, the mutual spacing between adjacent apertures of the or each row decreasing along the length of the row, being a maximum value at one end of the row and a minimum value at the other end of the row. The or each row of apertures may be sub-divided into a plurality of sub-groups of apertures, the mutual spacing between adjacent apertures of each sub-group being constant, and the mutual spacing between adjacent sub-groups decreasing along the length of the cable.

Abstract: A radiating cable is constructed from an inner conductor and a concentric outer conductor being separated from each other by a dielectric spacer; the outer conductor has openings of similar size and configuration but their density varies periodically in axial direction. In one example, the openings are arranged in circumferential rows and axial rows, the number of openings for circumferential row varies periodically in axial direction. In another example, a single axial row has its openings spaced in a periodically variable spacing.

Abstract: A method of manufacturing leaky coaxial cables having an array of apertures in the conductive outer layer. The total area of the apertures is a predetermined fraction of the surface area of the cable. A pair of strip conductors of particular widths are selected and wound around the inner conductor and dielectric at predetermined pitch angles. This provides apertures having a total area which is a predetermined fraction of the surface area of the cable, a predetermined shape and being of a predetermined number per unit length. By varying the pitch angle during winding the distribution of apertures and hence the coupling of the cable can be varied. By testing short sections of cables of different geometry a coupling function and an attenuation function can be calculated to provide data for winding cables with desired characteristics.

Abstract: A radiating cable communication system for a transportation undertaking is given useful fire-survival characteristics by incorporating on the surface of the cable dielectric, inside the outer conductor and so in the electric field, of the mica paper tape. This is much more effective than, for instance, using flame-retardant grades of polyethylene for the dielectric and flame-retardant grades of PVC for the sheath and, surprisingly, it has less effect on the electrical transmission characteristics of the cable.

Abstract: Uniform detection sensitivity along the periphery of an r.f. loop intruder detector system is realized by periodically electronically interchanging the input and termination ends of the system's leaky transmission line transmitting element. The intruder detector system comprises a length of leaky transmission line that encompasses the region to be protected, a receiving antenna within the protected region, an r.f. transmitter and a remotely located receiver and detector. R.F. energy is transmitted through the leaky transmission line and received by the receiving antenna and detector means to establish a normally quiescent field. Violation of the protected region by crossing the leaky transmission line disturbs the quiescent field condition and the intrusion event and the location is signaled by the detector. The effects of attenuation along the leaky transmission line are obviated by periodically switching the transmitter to alternate leaky transmission line ends.

Abstract: The detection, location and tracking of an intruder in an area to be protected is accomplished by dividing the area into a multiplicity of discrete regions, transmitting r.f. signals from transmitting transducers that comprise lengths of transmission lines deployed along the boundaries of the discrete regions, and receiving intrusion occurrence signals from receiving transducers located within each region. Violation of a boundary by an intruder results in an intrusion signal from the receiving transducers of as many as four possible adjacent regions thereby indicating an intrusion event. A coincidence logic circuit indicates which boundary has been violated. Intrusion occurrence signals are stored for suitable periods of time while past and current intrusion events are indicated on a display in order to locate and track intruders.

Abstract: A leaky coaxial cable is disclosed having an axial conductor, a dielectric layer coaxial along the length of the conductor and an outer conductive shield coaxial with the dielectric layer. The outer shield comprises a nonconductive elongate film carrier having a pair of spaced electrically conductive foil strips formed thereon which define a uniform width gap therebetween along the length of the film, the film being disposed about the circumference of the dielectric layer such that outer lateral edges of the foil strips overlap and the uniform width gap extends along the length of the cable. The film carrier may be applied on the dielectric layer either longitudinally thereof or by helically winding the film along the length of the dielectric layer. The cable also preferably includes at least one drain wire and an outer protective jacket.

Abstract: Radioelectric signals transmitted by a transmission line in the form of a sheathed cable having radiating sections whose length is chosen as a function of the wavelength in order to impart a directivity to their radial radiation or maximize the excitation of the monofilar mode in the downstream direction in relation to the transmitter.