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Browse Prior Art Database

ELECTRICALLY TUNABLE CAVITY FOR IMPROVED BANDWIDTH

IP.com Disclosure Number: IPCOM000006406D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2002-Jan-01
Document File: 1 page(s) / 45K

Publishing Venue

Motorola

Related People

James T Wiggenhorn: AUTHOR

Abstract

In radio products today an important parameter to have is wide bandwidth. Typically bandwidths of ten to twenty megahertz are achieved in today's modem designs. However, when requirements for exceptional selectivity are needed these wide bandwidths are. not possible. High selectivity is normally needed in repeater applications where the transmitter and receiver are both active at the same time. To prevent interference to each other a device such as duplexer is used to provide the necessary isola- tion. These typically have very narrow bandwidths and limit the frequency coverage ofthe system.

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MOTOROLA INC. Technical Developments Volume 15 May 1992

ELECTRICALLY TUNABLE CAVITY FOR IMPROVED BANDWIDTH

by James T Wiggenhorn

  In radio products today an important parameter to have is wide bandwidth. Typically bandwidths of ten to twenty megahertz are achieved in today's modem designs. However, when requirements for exceptional selectivity are needed these wide bandwidths are. not possible. High selectivity is normally needed in repeater applications where the transmitter and receiver are both active at the same time. To prevent interference to each other a device such as duplexer is used to provide the necessary isola- tion. These typically have very narrow bandwidths and limit the frequency coverage ofthe system.

  A design which uses cavities that can be electrically controlled would be a solution to this problem. The cavi- ties would be similar to ones used today in fixed tuned apphcatlons wdh the addition of several small solenoids in one end of the cavity. (see figure below) These would modify the resonant frequency of the cavity in steps as they were selected Duplexers today that might have a 300 khz bandwidth could be designed such that there would be several steps of 300 khz depending on the number of solenoids used. In fact frequency coverage of more than ten megahertz could be achieved using this method.

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OUTPUT

ELECTRICALLY TUNED CAVITY

B Motorola. 1°C. 19s2 47

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