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 method and apparatus is disclosed for automatically and exactly tuning a boradband filter. Upon the detection of a tuning change, the filter is automatically switched end to end so that the output terminal of the filter is connected to the radio frequency power source. Radio frequency in this application refers to any signals whose frequency facilitates propagation of data via electromagnetic waves. The input terminal is terminated into a known load such as 50 ohms and C1, an input variable reactance is adjusted until a 90.degree. phase relationship exists between the input resonator and the output resonator's node voltages. These actions set the exact tune condition for the broadband filter.

Abstract: A two resonator bandpass filter that is tunable is disclosed with each resonator consisting of three series connected inductors and a tuning capacitors. The inductors comprising each resonator are contained in a common enclosure isolated from each other by a ground shield having a fixed aperture opening for electromagnetic coupling between the two resonators. Shorting plugs are used as the bandswitching techniques for switching the bands of the resonators. Variable capacitors in each of the resonator's circuit provide for tuning of each band to a desired frequency.