In the traffic field there are inductive loops that are installed under the road to detect cars. We cut asphalt and install 3-4 loop of wires like the following picture.

The corners are cut diagnostically in order to avoid sharp edges, BUT my boss is emphasizing that this type is better than rectangular shape electrically. He says the more is the shape similar to circle the better performance.

Because cutting corners add extra effort and I found a solution to reduce sharp edge impact, I want to know: is it true and how much is it different?

enter image description here

  • $\begingroup$ There are a lot of factors at play (most importantly what the manufacturer of this equipment requires!) but I would suggest that one should want to avoid sharp edges AND maximize the area that the loop covers, so a circle is probably not going to "cut" it, because it may lose sensitivity towards the circumference. Having said that, I thought that the better design now is a figure 8 shaped inductive loop? Didn't they introduce that a few years ago? $\endgroup$ – CuriousOne Mar 7 '16 at 12:59
  • $\begingroup$ I saw an installing video, in that workers drill the corner in order to avoid sharp edge, so we don't care about edge, only performance that is matter. I see figure 8 shaped loop but that is also need more effort and cost (because of filling materials and more cutting). Do you have any ref about losing sensitivity in circumference of circle? $\endgroup$ – SAMPro Mar 7 '16 at 13:41
  • $\begingroup$ Not only are there a lot of factors, but some are more important than others. The shape of the inductance loop is one of the least important. The length of the cable connecting the loop to receiver/amplifier, depth of the loop, as well as "tight/clean" connections, are the most important electrical factors. Also, the labor costs to "cut" a circle are higher than cutting straight lines. $\endgroup$ – Guill Mar 10 '16 at 2:53

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