Abstract: A bandwidth-enhanced antenna system for operating on one of a plurality of selected frequency bands includes a whip or wire antenna element having band selection wires and a contiguous set of inductors arranged in series, each of the inductors being sufficiently separated from one another and being arranged such that the resonant frequency of any of said inductors is greater than the highest operating frequency of the plurality of frequency bands. Selector means is included provide a band select signal, and a plurality of switches each having a first terminal connected to a corresponding one of the inductors and a second terminal connected to the feed-end of the antenna element. The switches are responsive to the bandwidth select signal to allow communication using a selected one of the plurality of the frequency bands. An impedance matching network may be used for coupling an external receiver or transmitter to the feed-end of the antenna element.

Abstract: A monopole antenna adapted for efficiently radiating energy over an enhanced range of frequencies. The antenna includes a vertically inclined wire approaching one-quarter wavelength of said range of frequencies and a number of small-sized inductors installed along the length of said wire. The inductors are spaced apart so as to have negligible mutual coupling and are sized sufficiently small so that they do not have individual resonances over the range of frequencies for which the antenna is operational. The inductors provide a distributed reactance which allows the antenna to operate with greater efficiency over a broader range of frequencies.

Abstract: An improved miniature antenna is disclosed which provides an electrically short radiation pattern by providing shielding of selected portions of a current carrying conductor forming a loop antenna. The shielding is provided so that the shielded portion of the loop antenna does not cancel the radiation from an unshielded radiating portion of the antenna, thereby producing a uniform radiation pattern. A plurality of the current carrying elements formed by the shielded and unshielded portions may be coupled in a series and parallel relationship to provide optimum impedance matching at the frequency of operation of a transmitter or receiver.

Abstract: There is disclosed an antenna and coupling system for use in frequency hopping communication systems. The system includes a dual antenna configuration wherein the antennas are coupled in parallel to a tunable broadband coupler which provides a VSWR which is nominally less than 2:1 over the full hopping bandwidth of the system. The antenna and coupling system are so constructed that the coupler is operated over a plurality of passbands defining a broadband frequency range and each passband is of sufficient width such that several hopping band center frequencies can fall within a given passband. The passbands also overlap to permit continuous frequency coverage over the frequency range of the system.

Abstract: A high current low impedance antenna having an electrically short monopole radiation pattern is provided by shielding at least one of the segments or legs of a loop antenna so that the shielded leg has no cancelation effects and thereby produces the uniform radiation pattern of a short monopole antenna.