I have been toying with this idea for a few days now and I signed up here (after finding a link to an rc race timing system discussed on this site) hoping to gather some additional help with some questions I have. I'm an Art student that has a deep love for technology and an entrepreneurial spirit. This is my back story:

For the most part of my life, I have raced BMX bicycles (http://www.nbl.org). I love the sport with a passion like nothing else, but a lot of the systems used by the NBL are antiquated. For example, all finishes are recorded by people watching about 4' from the finish line. They have been testing a few systems for race timing, but nothing has panned out yet. (I'm assuming this is due to cost. I do know some of the "Decision makers" in the organization and I want to ask them specifics regarding this issue.) Additionally, All of the information is hand entered via a clerk and the list goes on. 

I had been thinking about how awesome it would be to develop an affordable RFID system that took care of Race timing, Registration, Bike Inspection and Race Stats. I'm going to school for interactive media and am proficient in many programming languages so I am not worried about that aspect of this project. I do have plenty of questions regarding RFID technologies that my research hasn't really been able to clarify.

Here is what I was thinking tech-wise for my project:

passive tags (price)

4  ~20' "gates" (1 after each turn and the finish line)

In my research, I've found that active tags are better over range but I have seen passive systems used for running that are similar to my goals. My main concern is with the gates that the riders need to pass through.

I've found two similar systems that are in place and I had some questions about them:

http://www.mylaps.com/index.php/us_eng/Websites/B2B/cycle/systems/championchip_system/system_components

They are using an "antenna mat" that they can daisy chain to make larger. How does this work? I mean, I know that you guys aren't developing their product but how do they go about making a wider antenna? I thought that antenna length was based on wavelengths? 

I don't really like the idea of an antenna mat, unless it is 1/2" or thinner. Is that plausible?

http://www.innovativetimingsystems.com/ITS-BronzeSystemInfo.html

This system looked to be more promising, but I'm concerned about "Spread". I was hoping to get a spread of 1 foot wide or narrower, as races can be tight. What do you think the spread of a system like that would be? In my initial estimate, gates would need to be ~20feet wide and I would like a tag reading section of about a foot or less. 

I was hoping to sell the "core" module for ~$500 or less and the additional "gates" for ~ $100 (although after a lot of research, it is probably going to be closer to $200 each gate) Does that sound possible? 

My last question is this:

I've found myself looking at the skyetek and alien technologies websites looking at their products. I'm confused as how the "readers" work. Aren't they basically a processor and an antenna? Why are different processors rated for different distances? Shouldn't that be based on the antenna? I then thought that maybe it was due to power, but couldn't you use a separate power supply to "amp up" the antenna? I think this was the bulk of my questions. I appreciate any input on that anyone can provide.

Thank you for your time!