Abstract: An apparatus, method, or computer-readable storage medium encoded with computer-executable instructions that, when executed by a computer, cause the computer to carry out a method for determining one or more directions of arrival of one or more coherent or incoherent signals with a single radio frequency channel. The apparatus may comprise: a plurality of antenna elements (110) configured to determine the one or more coherent or incoherent signals; a plurality of radio frequency switches (120) configured to selectively activate one or more of the plurality of antenna elements; and a radio frequency combiner (140) configured to combine a plurality of radio frequency signals from one or more selectively activated antenna elements of the plurality of antenna elements.

Abstract: A spiral antenna apparatus, which may comprise an antenna element disposed in two spiral arms in a vertical zigzag pattern. The apparatus may comprise an electromagnetic band gap cavity comprising: a ground plane, one or more layers of conductive patches, at least one pillar extending between the ground plane and a top layer of the one or more layers, and low dielectric foam disposed to fill gaps between the ground plane and the one or more layers and to fill gaps between the one or more layers. The apparatus may comprise a corrugated radio frequency choke disposed within the electromagnetic band gap cavity. At least one of the antenna element, the balun element, the electromagnetic band gap cavity, and the radio frequency choke may be fabricated using additive manufacturing.

Abstract: An apparatus, method, or computer-readable storage medium encoded with computer-executable instructions that, when executed by a computer, cause the computer to carry out a method for determining one or more directions of arrival of one or more coherent or incoherent signals with a single radio frequency channel. The apparatus may comprise: a plurality of antenna elements (110) configured to determine the one or more coherent or incoherent signals; a plurality of radio frequency switches (120) configured to selectively activate one or more of the plurality of antenna elements; and a radio frequency combiner (140) configured to combine a plurality of radio frequency signals from one or more selectively activated antenna elements of the plurality of antenna elements.

Abstract: A spiral antenna apparatus, which may comprise an antenna element disposed in two spiral arms in a vertical zigzag pattern. The apparatus may comprise an electromagnetic band gap cavity comprising: a ground plane, one or more layers of conductive patches, at least one pillar extending between the ground plane and a top layer of the one or more layers, and low dielectric foam disposed to fill gaps between the ground plane and the one or more layers and to fill gaps between the one or more layers. The apparatus may comprise a corrugated radio frequency choke disposed within the electromagnetic band gap cavity. At least one of the antenna element, the balun element, the electromagnetic band gap cavity, and the radio frequency choke may be fabricated using additive manufacturing.

Abstract: According to some aspects, an antenna is provided comprising a substrate, a first conductive region disposed on a first side of the substrate, a second conductive region disposed on a second side of the substrate, and a coaxial transmission line, an inner conductor of the coaxial transmission line electrically coupled to the first conductive region and an outer conductor of the coaxial transmission line electrically coupled to the second conductive region, wherein the second conductive region includes at least one structural feature that functions as a choke when the first and second conductive regions are operated together as an antenna. According to some aspects, an aerial vehicle comprising a conformal antenna is provided.

Abstract: According to some aspects, an antenna is provided comprising a substrate, a first conductive region disposed on a first side of the substrate, a second conductive region disposed on a second side of the substrate, and a coaxial transmission line, an inner conductor of the coaxial transmission line electrically coupled to the first conductive region and an outer conductor of the coaxial transmission line electrically coupled to the second conductive region, wherein the second conductive region includes at least one structural feature that functions as a choke when the first and second conductive regions are operated together as an antenna. According to some aspects, an aerial vehicle comprising a conformal antenna is provided.

Abstract: Reflector antennae and related structures and methods are described. The reflector antennae may have a deep f/D ratio and use an offset corrugated horn. Pivoting feed arms may be included for connecting a feed horn to a dish of the antenna. Radomes are also described, which may be formed of two or more pieces.

Abstract: A system for coupling a communication unit to an antenna. The system includes a tunable bandpass filter and a second tunable filter, such as a tunable low-pass filter, in parallel with the tunable bandpass filter. The system also includes a measurement and control unit configured to measure a frequency of a signal generated by the communication unit and to tune the tunable bandpass filter to pass the signal generated by the control unit.

Abstract: Antennae are described. The antennae may be GPS antennae configured to receive GPS signals at both the L1 and L2 frequencies. The antennae may include patches and polarizers which allow the antennae to receive right-hand circularly polarized GPS signals from GPS satellites. In some situations, the polarizers may include a meta-material. The meta-material may in some situations include circuit components formed on a suitable substrate.

Abstract: A system for coupling a communication unit to an antenna. The system includes a tunable bandpass filter and a second tunable filter, such as a tunable low-pass filter, in parallel with the tunable bandpass filter. The system also includes a measurement and control unit configured to measure a frequency of a signal generated by the communication unit and to tune the tunable bandpass filter to pass the signal generated by the control unit.

Abstract: Antennae are described. The antennae may be GPS antennae configured to receive GPS signals at both the L1 and L2 frequencies. The antennae may include patches and polarizers which allow the antennae to receive right-hand circularly polarized GPS signals from GPS satellites. In some situations, the polarizers may include a meta-material. The meta-material may in some situations include circuit components formed on a suitable substrate.

Abstract: Reflector antennae and related structures and methods are described. The reflector antennae may have a deep f/D ratio and use an offset corrugated horn. Pivoting feed arms may be included for connecting a feed horn to a dish of the antenna. Radomes are also described, which may be formed of two or more pieces.

Abstract: A balun component or structural subassembly, for use in conjunction with an antenna radome assembly, comprises a two-sided printed circuit board substrate having a longitudinal axis, wherein each side of the two-sided printed circuit board substrate is asymmetric with respect to itself but is in effect anti-symmetric with respect to the opposite side of the two-sided printed circuit board substrate in a 180° out-of-phase manner such that the entire two-sided printed circuit board balun component or structural subassembly exhibits diametrical symmetry with respect to the longitudinal axis of the overall two-sided printed circuit board substrate.

Abstract: A balun component or structural subassembly, for use in conjunction with an antenna radome assembly, comprises a two-sided printed circuit board substrate having a longitudinal axis, wherein each side of the two-sided printed circuit board substrate is asymmetric with respect to itself but is in effect anti-symmetric with respect to the opposite side of the two-sided printed circuit board substrate in a 180° out-of-phase manner such that the entire two-sided printed circuit board balun component or structural subassembly exhibits diametrical symmetry with respect to the longitudinal axis of the overall two-sided printed circuit board substrate.

Abstract: An compact and rugged antenna system particularly suited to direction finding includes a plurality of antenna arrays for receiving respective frequency bands and colocated on a mast with separation between antenna arrays along the mast. The mast includes a coil wound of an insulator and functioning as a loaded inductor to shift the mast resonance out of the frequency band of the antenna system. A VHF dipole array having elements shaped to reduce scattering to UHF and SHF arrays is supported on movable arms which allow retraction that reduces height and provides mechanical protection to one or more other arrays as well as damping against vibration by contacting the mast with shaped portions of the dipole elements. The bowtie elements of the UHF array are angled at a central region to optimize array diameter at low UHF frequencies. A finned RF electronics housing is preferably provided which reduces solar loading and dissipates heat from antenna electronics.