ATEX portable two way radios are different from non-intrinsically safe and TIA-4950 (UL-914) radios, in that the transmit power is less than 1W. This means that there are some things that you need to think about when it comes to designing the system.
The transmit power from the portable radios is 1W. This means that the talk-in range is significantly less than non-ATEX radios. The number of sites covering a defined area therefore needs to be increased, or you need to employ satellite receivers.
Wherever possible, you should try to use the whip (full length) antenna, as these have higher gain when compared to stubby antennas.
Since repeaters and associated equipment will be connected to the mains, these cannot be installed in the hazardous area. This means that what may seem the best RF site. is not usable due to this restriction.
Since all (or nearly all) radio users will be portable users working inside a plant, it makes sense not to use a traditional high site (e.g. building or mountain) and a very high gain antenna. A high gain antenna has a very narrow vertical beamwidth, and when mounted on top of a high building or mountain, could produce overshoot.
Usually, a lower gain antenna mounted low down and close to the operational area provides the best coverage - often these low sites are able to penetrate buildings better than building or mountain-top RF sites. A mountain-top RF site could sometimes be affected by ducting, especially in regions where air temperature and moisture can vary.
Leave a Comment