Abstract: A high-gain digitally tuned antenna system comprises a modified swept-back fractal (MSBF) radiator element, with the fractal preferably being a Sierpinski carpet fractal based on a parallelogram. A digital tuning circuit coupled to the radiator comprises an array of inductors which can be selectively connected to form a network which tunes the antenna system to a selected tuning frequency. The system is preferably arranged to selectively connect the inductors in series such that the combined inductances substantially cancel the capacitance of the radiator at a selected tuning frequency. The antenna system is preferably arranged to operate over the 30-88 MHz, 108-174 MHz, and 225-600 MHz bands, with a radiator height of 15? or less.

Abstract: A high-gain digitally tuned antenna system comprises a modified swept-back fractal (MSBF) radiator element, with the fractal preferably being a Sierpinski carpet fractal based on a parallelogram. A digital tuning circuit coupled to the radiator comprises an array of inductors which can be selectively connected to form a network which tunes the antenna system to a selected tuning frequency. The system is preferably arranged to selectively connect the inductors in series such that the combined inductances substantially cancel the capacitance of the radiator at a selected tuning frequency. The antenna system is preferably arranged to operate over the 30-88 MHz, 108-174 MHz, and 225-600 MHz bands, with a radiator height of 15? or less.

Abstract: Antenna system embodiments are illustrated that include a planar, top-loaded dipole antenna and a planar elliptical dipole antenna arranged substantially coplanar and within the top-loaded dipole antenna. These antenna structures facilitate their combination with tuning coil chains, baluns and impedance matching circuits to operate over multiple frequency bands. System embodiments exhibit high gain and selectivity and may be digitally tuned over wide frequency bands (e.g., 30-600 MHz). The embodiments may be digitally tuned to support operational modes such as frequency hopping to thereby realize a secure communication system. Because these embodiments are configured to operate in the absence of a ground plane, they are especially suited for mounting on various portions of an aircraft's structure. For example, they may be configured as winglets and situated far out on wingtips to thus free the remainder of an aircraft's structure for other operational systems.

Abstract: Antenna system embodiments are illustrated that include a planar, top-loaded dipole antenna and a planar elliptical dipole antenna arranged substantially coplanar and within the top-loaded dipole antenna. These antenna structures facilitate their combination with tuning coil chains, baluns and impedance matching circuits to operate over multiple frequency bands. System embodiments exhibit high gain and selectivity and may be digitally tuned over wide frequency bands (e.g., 30-600 MHz). The embodiments may be digitally tuned to support operational modes such as frequency hopping to thereby realize a secure communication system. Because these embodiments are configured to operate in the absence of a ground plane, they are especially suited for mounting on various portions of an aircraft's structure. For example, they may be configured as winglets and situated far out on wingtips to thus free the remainder of an aircraft's structure for other operational systems.

Abstract: Compact top-loaded, fractal monopole antenna system embodiments are provided for multi-band airborne operation over ultrabroadband ranges (e.g., 30 to 2000 MHz). These multi-band embodiments are self-contained, aerodynamic and compact (e.g., blade height less than 9.5 inches) and are power efficient with a low return loss (e.g., less than ?7 dB). System embodiments include a set of impedance-matching circuits configured to substantially match an antenna impedance to a predetermined system impedance over a set of predetermined frequency bands. In an embodiment, at least one impedance-matching circuit includes a chain of selectable air-core inductors which are novelly arranged to improve radiation efficiency and prevent damage to support substrates. In an embodiment, a lowest-frequency one of the impedance-matching circuits is configured to process signals having a maximum wavelength ?max wherein a fractal member is configured with a length that does not exceed ?max/40.

Abstract: Compact top-loaded, fractal monopole antenna system embodiments are provided for multi-band airborne operation over ultrabroadband ranges (e.g., 30 to 2000 MHz). These multi-band embodiments are self-contained, aerodynamic and compact (e.g., blade height less than 9.5 inches) and are power efficient with a low return loss (e.g., less than ?7 dB). System embodiments include a set of impedance-matching circuits configured to substantially match an antenna impedance to a predetermined system impedance over a set of predetermined frequency bands. In an embodiment, at least one impedance-matching circuit includes a chain of selectable air-core inductors which are novelly arranged to improve radiation efficiency and prevent damage to support substrates. In an embodiment, a lowest-frequency one of the impedance-matching circuits is configured to process signals having a maximum wavelength ?max wherein a fractal member is configured with a length that does not exceed ?max/40.