Hello, I am looking to build a simple low budget running race timing system using the SEN-14066/M6E Nano with an external antenna. I shall preface this by saying I have never built anything using RFID so only understand the basic concepts and am not sure what to expect in terms of location accuracy in the real world. Please be gentle 
Primarily it would be used for sprint timing where there are 8 lanes at 1.2metres wide, a total of 9.6metres across the width of the track, and I would like to identify the point at which each RFID tag crossed the finish line as accurately as possible, allowing for potentially 8 runners arriving at once. It would also be used for simple lap counting as each tag completes a full lap of the track for up to 100 competitors.
I understand it is possible to monitor the tag read strength to approximate when the tag was closest to the antenna.
Some questions please :
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If I were to use the Sparkfun suggested WRL-14131 antenna, could this be located/orientated in such a way to give a narrow/linear read window that could be aligned with the finish line ? Perhaps one edge of it’s signal area aligned across the track ?
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If the antenna was simply pointing across the finish line, could I simply find the strongest signal read for each RFID tag and assume that was the point the tag crossed the centre of the detection field ?
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Could multiple antenna be used with this module, positioned to read different lanes in an overhead gantry ?
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Is there another type of antenna, perhaps a long linear cable that could be run along the finish line that could be used with the M6E nano that would be better suited to the job ?
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The RFID tags could be fitted to runners shoes such that the tag passes close to the antenna (within 500mm) if it’s on the finish line. Is there another RFID reader that might be suited to the application, perhaps multiple individual lane readers sitting on the ground that I network together ?
Some races may have 50-100 participants that need to be individually identified so any sort of gate/opto trip wire won’t be enough, I’ll need to read an ID. The only other relatively cheap possibility I’ve thought of would be overhead IR readers with runners carrying IR transmitters, but attaching them reliably in line of sight could be a challenge.
A linear antenna or at least an antenna that could span 10 metres and give an accurate runner location with the M6E Nano seems like the perfect solution if it’s at all possible. It could potentially be mounted overhead on the centre of the track and read 5 metres either side if that was possible.
Thanks for any guidance or ideas.