A direction-finding antenna system is described. The direction-finding antenna system comprises a plurality of tapered dipole antenna elements arranged in circular array around a central axis. Each tapered dipole antenna element comprises a pair of rectangular elongated antenna elements mounted radially from said central axis and configured to be curved such that a distance between said pair of rectangular elongated antenna elements is larger at periphery of the system with respect to center thereof.

A filter which stops the propagation of an electromagnetic wave of a predetermined frequency band in a signal line or a power supply line is provided. This filter is a conductor connected to the signal line or the power supply line. This conductor is configured to include a linear portion. The first portion of the linear portion with an end portion connected to the signal line or the power supply line has the first width, and the second portion different from the first portion of the linear portion has the second width different from the first width.

A method of maximizing the radiation pattern at broadside of a dipole antenna. The antenna is formed with a dipole wire having a sleeve centered along the length of the dipole wire. This sleeve is made from a conductive material and has a length relative to the dipole length that causes the dipole antenna to have an elevation gain pattern that maintains a peak at zero elevation over a much greater bandwidth than a conventional dipole.

A method of maximizing the radiation pattern at broadside of a dipole antenna. The antenna is formed with a dipole wire having a sleeve centered along the length of the dipole wire. This sleeve is made from a conductive material and has a length relative to the dipole length that causes the dipole antenna to have an elevation gain pattern that maintains a peak at zero elevation over a much greater bandwidth than a conventional dipole.

The invention relates to an antenna designed to emit and/or receive surface waves with a decametric, hectometric or kilometric central wavelength .sub.0, characterised in that it comprises at least one horizontal wire aerial element of between 0.5.sub.0 and .sub.0 in length, and at least three vertical wire aerial elements of the same length between 0.03.sub.0 and 0.1.sub.0, arranged in a same plane and each comprising an upper end and a lower end, said upper ends being connected to the horizontal wire aerial element, said lower ends being designed to be connected to a conducting medium having a substantially horizontal surface. The invention also relates to an antenna, an antenna array and a use of an antenna or of an antenna array.

The invention relates to an antenna designed to emit and/or receive surface waves with a decametric, hectometric or kilometric central wavelength .sub.0, characterised in that it comprises at least one horizontal wire aerial element of between 0.5.sub.0 and .sub.0 in length, and at least three vertical wire aerial elements of the same length between 0.03.sub.0 and 0.1.sub.0, arranged in a same plane and each comprising an upper end and a lower end, said upper ends being connected to the horizontal wire aerial element, said lower ends being designed to be connected to a conducting medium having a substantially horizontal surface. The invention also relates to an antenna, an antenna array and a use of an antenna or of an antenna array.

A dual ultra-wideband electronically scanning antenna linear array and a method for producing same is disclosed. In one embodiment, the antenna is comprised of circuit board-based multi-layered sections with integrated feeds. A first dielectric layer or substrate has a thin metal coating on the bottom surface to form a signal ground and metal coating on the top surface where capacitively loaded radiating dipoles are etched. Each of the dipole elements are connected to an associated conductive antenna feed disposed on a bottom surface of another dielectric layer disposed below the first dielectric layer.

A dual ultra-wideband electronically scanning antenna linear array and a method for producing same is disclosed. In one embodiment, the antenna is comprised of circuit board-based multi-layered sections with integrated feeds. A first dielectric layer or substrate has a thin metal coating on the bottom surface to form a signal ground and metal coating on the top surface where capacitively loaded radiating dipoles are etched. Each of the dipole elements are connected to an associated conductive antenna feed disposed on a bottom surface of another dielectric layer disposed below the first dielectric layer.

An antenna includes a first dipole arm and a second dipole arm. The first dipole arm is connected to a first conductor and is formed of a first conducting material. The first dipole arm extends in an axial direction from the first conductor. The second dipole arm is connected to a second conductor that is distinct from the first conductor and is formed of a second conducting material. The second dipole arm extends in the axial direction from the second conductor and is wound around the first dipole arm to form a number of loops. The second dipole arm does not contact the first dipole arm. An axial length of the second dipole arm in the axial direction is less than 90% of an axial length of the first dipole arm in the axial direction.

An antenna includes a first dipole arm and a second dipole arm. The first dipole arm is connected to a first conductor and is formed of a first conducting material. The first dipole arm extends in an axial direction from the first conductor. The second dipole arm is connected to a second conductor that is distinct from the first conductor and is formed of a second conducting material. The second dipole arm extends in the axial direction from the second conductor and is wound around the first dipole arm to form a number of loops. The second dipole arm does not contact the first dipole arm. An axial length of the second dipole arm in the axial direction is less than 90% of an axial length of the first dipole arm in the axial direction.