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Multiband public safety radio using a multiband RFIC with an RF multiplexer-based antenna interface

NCJ Number
Date Published
October 2008
23 pages

This presentation slideshow lays out the steps involved in the development of a prototype radio capable of operation over a large range of frequency bands for public safety applications.


The authors of this slideshow present the development of a multiplexer, which may be poorly matched with the antenna impedance, in such a way that the front end is dominated by the external noise and provide acceptable sensitivity. The authors lay out the motivation for multiband multimode radios (MMRs); provide a system diagram of the prototype as well as the Motorola Direct Conversion RFIC; describe the advantages of (radio frequency integrated circuits) RFIC-based direct conversion; and discuss antenna interfacing and models, external noise and optimum noise figure (NF), multiplexer architecture, and results. The authors note that challenges of the project included the requirement of an amplifier with better NF than is commonly used, realizing a small filter footprint, and building a good user interface to control the whole radio. They conclude that the principal advantage over reconfigurable matching techniques is simultaneous access to multiple bands; performance of the RFIC-based design is still short of public safety selectivity and dynamic range requirements; and the RF multiplexer optimized to an antenna impedance with external noise dominance constraint allowed good performance in multiple bands, it also had good results with 20cm 5mm rod antenna, but performance was reduced with commercial 433MHz antenna. The authors suggest that co-design of antenna and multiplexer might be advantageous.

Date Published: October 1, 2008