Abstract: Disclosed is a tapered double balun for use with rotationally-symmetrical, frequency-independent antennas that are fed using spiral-mode number 2. The tapered double balun may be used to provide a four-terminal line, where all terminals carry the same voltage, but adjacent terminals are out of phase and opposite terminals are in phase. The antennas may be spirals, sinuous, or other four-arm antennas. The tapered double balun is a stripline device comprising two outer ground planes and a center conductor that is dielectrically separated from the ground planes. The outer ground planes each taper from a wide dimension at the connector end of the device to a narrow dimension at the antenna end of the device. The narrow opposing strips comprising the ground planes are configured to connect to two opposed arms of the antenna.

Abstract: Disclosed is a tapered double balun for use with rotationally-symmetrical, frequency-independent antennas that are fed using spiral-mode number 2. The tapered double balun may be used to provide a four-terminal line, where all terminals carry the same voltage, but adjacent terminals are out of phase and opposite terminals are in phase. The antennas may be spirals, sinuous, or other four-arm antennas. The tapered double balun is a stripline device comprising two outer ground planes and a center conductor that is dielectrically separated from the ground planes. The outer ground planes each taper from a wide dimension at the connector end of the device to a narrow dimension at the antenna end of the device. The narrow opposing strips comprising the ground planes are configured to connect to two opposed arms of the antenna.

Abstract: A compact broadband microstrip antenna for mounting to one side of a ground plane comprises a closed (usually circular) array of antenna elements positioned to one side of a substrate for spacing the antenna elements a selected distance above the ground plane, the antenna elements being adapted to be electrically driven out of phase from one another to excite one or more spiral modes. In another form, a compact microstrip antenna comprises one or more antenna elements positioned to one side of a magnetic substrate for spacing the antenna elements a selected distance from a ground plane, the magnetic substrate being chosen to have a relative permittivity which is roughly equal to its relative permeability. In a third form, a microstrip antenna is adapted for operating in a single mode and radiation from other modes is suppressed by varying the spacing above the ground plane in the radiation zones so that only radiation in the desired mode is fostered.

Abstract: A shared aperture, multifunction conformable antenna has a spiral-mode microstrip (SMM) antenna portion having a spacer for maintaining the SMM antenna in spaced relationship to a ground plane, with dielectric material therebetween. The SMM antenna portion is substantially surrounded by a loop antenna which is spaced therefrom and which is electrically connected to the spiral-mode portion by a high frequency choke to block FM broadcast band signals from the SMM antenna. An AM-broadcast-band-blocking capacitor functions to route AM signals to the SMM antenna portion. The spiral-mode antenna receives signals at frequencies above 300 MHz, the loop antenna receives signals in the FM band, and both the loop antenna and the spiral-mode antenna receive signals in the AM band.

Abstract: A compact broadband microstrip antenna for mounting to one side of a ground plane comprises a closed (usually circular) array of antenna elements positioned to one side of a substrate for spacing the antenna elements a selected distance above the ground plane, the antenna elements being adapted to be electrically driven out of phase from one another to excite one or more spiral modes. In another form, a compact microstrip antenna comprises one or more antenna elements positioned to one side of a magnetic substrate for spacing the antenna elements a selected distance from a ground plane, the magnetic substrate being chosen to have a relative permittivity which is roughly equal to its relative permeability. In a third form, a microstrip antenna is adapted for operating in a single mode and radiation from other modes is suppressed by varying the spacing above the ground plane in the radiation zones so that only radiation in the desired mode is fostered.

Abstract: A multioctave microstrip antenna for mounting to one side of a ground plane and including a metal foil spiral-mode antenna element and a dielectric substrate positioned between the antenna element and the ground plane. The spiral-mode antenna element has a frequency-independent pattern formed therein, such as a sinuous, log-periodic, tooth, or spiral pattern. The antenna can be mounted substantially flushly to the surface of a structure without perforating the surface of the structure and can be conformed thereto. The antenna exhibits a broad bandwidth, typically on the order of 600%.

Abstract: A magnetic corrugated horn antenna system is disclosed. This system includes a magnetic hybrid-mode horn antenna composed of a circular waveguide and a corrugated horn antenna which has a thin magnetic coating on its inner wall. The corrugation of the conical horn helps it to produce equal E-plane and H-plane patterns with low sidelobes. The magnetic coating can enhance or duplicate the beneficial effects of the corrugation, while avoiding the high gain loss and poor patterns reported in prior art systems that relay only on corrugated horns.