To cover two separate lanes with the same timing line, or to create a main and backup timing line with one decoder, you may want to split your 4.8 m antenna into two parts of 2.4 m.

Note that we do not recommend using a split antenna as a main and backup line on a timing point that requires a high level of precision.

Here is why: a decoder connected to two consecutive timing lines should see two peaks in signal strength for each participant, but it is impossible to define a reaction time that would ensure that these two peaks are systematically treated as two separate detections, regardless of the speed of the participant and the environment. If the second peak is detected before the reaction time has elapsed, the decoder will take the highest peak to record the time, which could be on either timing line.

A single detection line per decoder is the only way to guarantee precision at your finish line. If you are using only one chip per bib, then it is best to use two decoders with one detection line each at the finish. More information about Combining multiple ground antennas and decoders.

A split antenna is however perfect for timing points where you need to improve the read rate and do not need high precision, for example at the swim exit of a triathlon.

You can find more information about the way times are calculated by our passive system in this article about Detection Setup

When connecting 2 lines of mats to a single decoder it is recommended to keep the maximum distance between the 2 mats to a maximum of around 2 meters. When spreading the mats further apart you create 2 distinct read zones each of which is only active half the time due to the multiplexing of the decoder.

The following video shows how to separate your ground antenna.