Abstract: A log-periodic antenna coupled to a channelizer is described in which matched scale constants for the antenna and the channelizer are used to achieve substantially identical coupling over each fractional bandwidth channel. Embodiments for simultaneous dual polarization operation are described as well as embodiments suited for planar lithographic fabrication.

Abstract: A log-periodic antenna coupled to a channelizer is described in which matched scale constants for the antenna and the channelizer are used to achieve substantially identical coupling over each fractional bandwidth channel. Embodiments for simultaneous dual polarization operation are described as well as embodiments suited for planar lithographic fabrication.

Abstract: The present invention relates to connecting and impedance matching a balanced electrical signal, such as that received by an antenna, with an unbalanced transmission circuit, such as that delivered to an amplifier. A planar circuit board is described that delivers signals having opposite polarization collected by different antenna arms to a location for convenient connection to a twin-lead transmission line. Circuit topologies for the circuit board are described that provide relatively low loss and low cross-coupling. A tapered microstrip balun is also described that includes two conducting microstrips on opposing faces of a dielectric separator. Stepped or tapered microstrips at the balanced input port of the balun provide an impedance transforming section electrically connecting to a mode transducing section, in which one of the microstrips tapers outward to form a substantially wider strip. Appropriate choice of parameters is shown to lead to favorable performance in a compact balun.

Abstract: A self-similar log-periodic antenna is described comprising a plurality of substantially triangular conductive elements, 4, symmetrically disposed in either planar or curved configurations about a central conductive boom to form an antenna arm. Two or more antenna arms are assembled into an antenna by symmetrically locating such antenna arms substantially in the shape of a pyramid (for planar arms) or in a conical shape (for curved arms). Some embodiments include a conductive fin, 5, to reduce cross-polarization coupling between antenna arms. Some embodiments include a grounded conductive shield on the interior of the antenna providing electromagnetic shielding for the interior region of the antenna while preserving the self-similar geometry of the antenna and shield combination.

Abstract: The present invention relates to connecting and impedance matching a balanced electrical signal, such as that received by an antenna, with an unbalanced transmission circuit, such as that delivered to an amplifier. A planar circuit board is described that delivers signals having opposite polarization collected by different antenna arms to a location for convenient connection to a twin-lead transmission line. Circuit topologies for the circuit board are described that provide relatively low loss and low cross-coupling. A tapered microstrip balun is also described that includes two conducting microstrips on opposing faces of a dielectric separator. Stepped or tapered microstrips at the balanced input port of the balun provide an impedance transforming section electrically connecting to a mode transducing section, in which one of the microstrips tapers outward to form a substantially wider strip. Appropriate choice of parameters is shown to lead to favorable performance in a compact balun.

Abstract: A self-similar log-periodic antenna is described having a substantially frequency independent range of operation. An antenna arm is described comprising a plurality of substantially triangular conductive elements, 4, symmetrically disposed about a central conductive boom. Adjacent triangular elements differ by a constant scale factor from a largest element to a smallest element wherein the largest and smallest elements relate to the bandwidth of the antenna. Both planar and curved antenna arms are described. Other embodiments of the antenna arms include a conductive fin, 5, located along the boom and having a shape so as to preserve the self-similarity of the arm. The conductive fin is shown to reduce cross-polarization coupling when the antenna arms are assembled into an antenna. Two or more such antenna arms are assembled into an antenna by symmetrically locating such antenna arms in the shape of a pyramid (for planar arms) or in a conical shape (for curved arms).

Abstract: A non-planar log-periodic antenna feed with low ohmic loss, intermediate gain multioctave bandwidth, and dual polarization can be integrated with a low-noise MMIC amplifier, at ambient or cryogenic temperatures. Long, lossy transmission lines with nearly 1 dB loss, normally required for connecting log-periodic antennas to microwave signal detection circuits, are unnecessary in this design. Amplifiers are positioned close to the antenna terminals at the vertex of the antenna, inside a square pyramidal shield with half the opening angle of the antenna arms. The non-obvious idea is that a conductor enclosing a large volume of self-similar shape between the antenna arms enhances gain while preserving the frequency-independence of the log-periodic antenna over its operating bandwidth. The design has been reduced to practice. A 1-10 GHz prototype has been range tested. A small microwave telescope which incorporates this feed can achieve over multioctave bandwidths an A/T (sensitivity) that is unprecedented.

Abstract: A self-similar log-periodic antenna is described comprising a plurality of substantially triangular conductive elements, 4, symmetrically disposed in either planar or curved configurations about a central conductive boom to form an antenna arm. Two or more antenna arms are assembled into an antenna by symmetrically locating such antenna arms substantially in the shape of a pyramid (for planar arms) or in a conical shape (for curved arms). Some embodiments include a conductive fin, 5, to reduce cross-polarization coupling between antenna arms. Some embodiments include a grounded conductive shield on the interior of the antenna providing electromagnetic shielding for the interior region of the antenna while preserving the self-similar geometry of the antenna and shield combination.

Abstract: A self-similar log-periodic antenna is described comprising a plurality of substantially triangular conductive elements, 4, symmetrically disposed in either planar or curved configurations about a central conductive boom to form an antenna arm. Two or more antenna arms are assembled into an antenna by symmetrically locating such antenna arms substantially in the shape of a pyramid (for planar arms) or in a conical shape (for curved arms). Some embodiments include a conductive fin, 5, to reduce cross-polarization coupling between antenna arms. Some embodiments include a grounded conductive shield on the interior of the antenna providing electromagnetic shielding for the interior region of the antenna while preserving the self-similar geometry of the antenna and shield combination.