Browse Prior Art Database

TRANSMIT-RECEIVE SWITCH WITH SELECTABLE ANTENNA PORTS

IP.com Disclosure Number: IPCOM000005663D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2001-Oct-24
Document File: 1 page(s) / 74K

Publishing Venue

Motorola

Related People

Kai Siwiak: AUTHOR

Abstract

A two PIN diode T/R switch is configured to switch either of two antennas between a transmitter and receiver. No PIN diode current is required when either antenna port is used in the receive mode. The circuit also provides more than 26 dB second harmonic attenuation across a 25% frequency bandwidth.

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MOZOROlA Technical Developments Volume 7 October 1987

TRANSMIT-RECEIVE SWITCH WITH SELECTABLE ANTENNA PORTS

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by Kai Siwiak

   A two PIN diodeT/R switch is configured to switch eitherof twoantennas between atransmitterand receiver. No PIN diode current is required when either antenna port is used in the receive mode. The circuit also provides more than 26 dB second harmonic attenuation across a 25% frequency bandwidth.

   One port, the Standard port, can connect the usual transceiver mounted antenna, while the second port, the Remote port, can be used for ConvertaCorn or public safety microphone attachment. The key features are that no movable mechanical switch is used in the transceiver, no PIN diode current is drawn in receive mode, and thecircuitry provides more than a25% bandwidth with substantial harmonic suppression as anatural con- sequence of the circuit topology. The circuit, shown in FIG. 1, is configured for operation in the 400 to 500 MHz range as follows. Voltage source V, and resistor R, represent the transmitter while R, represents the receiver input impedance of a transceiver. PIN diodes D,, D2 and the 90 degree phase shift network Co, LO, C, L*, form a conventional quarter wave type transmit receive switch. Series circuit C, L?, is resonant at a harmonic fre- quency (the second harmonic in this example) while having the same reactance as CO at the fundamental fre- quency (450 MHz here). Both PIN diodes are on and require current only in transmit mode. Note T is the usual T/R switch antenna port. Here, node T connects to a passive secondary switch arrangement which allows con- stant connection to a Standard antenna represented by R,...