Abstract: A yagi antenna having a director element, a half-wave active dipole element, and a reflector element mounted on an antenna boom. All antenna elements are rods that are telescopically adjustable in length from a collapsible position to an operating length for a predetermined frequency of operation, and removable from threaded mounting for storage. The director element and reflector element are slidably adjustable on the antenna boom for independent spacing with respect to the half-wave active dipole element. The antenna boom has two mast support holes; one for horizontal polarization and the other for vertical polarization. A ferrite core member surrounds a coaxial cable connecting the half-wave active dipole element to a coaxial connector, and provides balun action between the coaxial cable and a balanced antenna feed point.

Abstract: An Isolation Differential Combiner which accepts signals from two spaced vertical whip antenna elements and which are then combined through delay lines so that the resulting said reception pattern is a cardioid signal pattern at the combiner outputs. The isolation of the two signals is accomplished by connecting wide-band balanced transformers as hybrids. The differential component of the two signals present at the hybrid combiner is available at each secondary winding of each wide-band balanced transformer.

Abstract: A direction finding receiver contained in a hand held portable housing with a ferrite rod antenna mounted in and protruding through the housing so that when the antenna axis points to the radio frequency signal source to be direction found, a null is obtained in the signal level. The antenna is coupled to the receiver circuit which comprises a broadband fixed tuned radio frequency amplifier having low sensitivity, a modulation oscillator used to modulate the broadband fixed tuned rf amplifier by tone injection when a steady carrier is present, a demodulator for demodulating the rf signal, and an audio amplifier for amplifying the demodulated signal.