Motorola Corporation

Michael Scott Pieper

Henry Hoang Nguyen

Brian Keith Smith

David Pok Kwan

A multi-frequency antenna apparatus includes an open-ended slot antenna ( ) operable at high frequencies, cascaded in series with a antenna element ( ) operable at low frequencies, results in two distinct antennas fed by a single excitation port ( ). A U-shaped conductive strip ( ) defining the slot antenna ( ) has a ground connection ( ) at one end near the open-ended side of the slot antenna ( ) and a virtual feed point ( ) on the other end coupled to the antenna element ( ). The electrical length from the ground connection ( ) to the feed point is about &frac14; of a wavelength of the first frequency creating a virtual open at the feed point ( ).

Multi-frequency slot antenna apparatus

A processing system ( ) defines ( ) a plurality of bins ( ) within a sliding time window, each bin for storing a total transmit duration of a predetermined number of frames assigned to each bin. The processing system then determines ( ) a mean transmit duration per frame for a next one of the plurality of bins to be processed. The processing system subtracts ( ) the mean transmit duration per frame from the total transmit duration of the one of the plurality of bins, when a next frame begins to be processed; and calculates ( ) a transmit duty cycle for the sliding time window, the transmit duty cycle calculated as if a requested transmit duration for the next frame were to be allowed. The processing system also delays ( ) a transmission of the next frame, when the transmit duty cycle is greater than a maximum allowable transmit duty cycle.

Method and apparatus in a two-way radio messaging unit for limiting a total transmission duration within a sliding time window

An antenna ( ) includes a rectangular dielectric substrate ( ); and a U-shaped conductive strip attached to a first surface of the substrate, the U-shaped conductive strip having two side members ( ), each about one-eighth a predetermined wavelength in length, and an end member ( ) forming a substantially rectangular slot ( ) extending parallel to the long edges of the substrate, the slot closed at a first end ( ) by the end member, and open at a second end ( ). The antenna further includes a microstrip feed line ( ) attached to a second surface of the substrate opposite and parallel to the first surface for coupling an RF signal between the antenna and an RF device ( ), the microstrip feed line extending across and perpendicular to the slot proximate the second end of the slot, and further extending across a portion of the two side members; and a ground point ( ) electrically coupled to a first one of the two side members of the U-shaped conductive strip and positioned proximate the second end of the slot.

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Fort Worth, TX, United States of America

Michael Scott Pieper