title: The design and performance of a 2.5-GHz telecommand link for wireless biomedical monitoring.
abstract: This paper details the implementation and operational performance of a minimum-power 2.45-GHz pulse receiver and a companion on-off keyed transmitter for use in a semi-active, duplex RF biomedical transponder. A 50-ohm microstrip stub-matched zero-bias diode detector forms the heart of a body-worn receiver that has a (CMOS baseband amplifier consuming 20 microA from +3 V and achieves a tangential sensitivity of -53 dBm. The base transmitter generates 0.5 W of peak RF output power into 50 ohms. Both linear and right-hand circularly polarized Tx-Rx antenna sets were employed in system reliability trials carried out in a hospital Coronary Care Unit. For transmitting antenna heights between 0.3 and 2.2 m above floor level, transponder interrogations were 95% reliable within the 67-m2 area of the ward, falling to an average of 46% in the surrounding rooms and corridors. Overall, the circular antenna set gave the higher reliability and lower propagation power decay index.
authors.affiliation: The Northern Ireland Bioengineering Centre & School of Electrical and Mechanical Engineering, University of Ulster, Newtownabbey, Northern Ireland, UK.
authors.forename: G C
authors.initials: GC
authors.lastname: Crumley
authors.forename: N E
authors.initials: NE
authors.lastname: Evans
authors.forename: W G
authors.initials: WG
authors.lastname: Scanlon
authors.forename: J B
authors.initials: JB
authors.lastname: Burns
authors.forename: T G
authors.initials: TG
authors.lastname: Trouton
mesh_terms: D003325:Coronary Care Units; D015716:Electrocardiography, Ambulatory; D004867:Equipment Design; D006801:Humans; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D011846:Radio Waves; D017216:Telemedicine / Q000295:instrumentation*