In the package editor how do I create a polygon pad with right angled corners?

The corners are rounded unless I set the width to zero, but then this causes DRC errors. I have also read in forums that zero width polygons causes the Gerber files to become extremely large.

I would like my polygon corners to have nice right angles with no curves. How can I do this in Eagle?

Update: The reason why I need right angled corners is that I am creating an antenna following a reference design, and it shows right angled corners. The antenna is the BLE trace antenna, Cypress document AN91445.pdf. See picture below.

enter image description here


1 Answer 1


You can't.

I don't like writing such short answers, but that's really all there is to say, you can't. Make the width something like 6mil (or whatever you minimum width DRC setting is) and then work with it. 6mil is tiny so you probably won't even notice it is rounded once manufactured, and unless you have some absolutely critical need for a perfect angle, then there are more important things in the design process to worry about.

Alternative Answer

Based on your update, there may be a way to do it.

You will need to be using the rectangle tool. Draw a series of boxes of the correct size, overlapping so that they form the shape you want. However these rectangles cannot belong to a signal/net. In order to connect it, you will have to draw a wire which goes up to the antenna and overlaps into it.

The overlapping rectangles shouldn't cause DRC errors where they overlap, but will give you a DRC error at the point where your signal wire intersects it. You'll just have to ignore this error.

What I am not 100% sure on is what Eagle does with rectangles in gerbers. For many things (including arcs with a cap set to flat), the Eagle CAM processor converts everything into lines. I presume this also applies to rectangles (haven't tried). If this is the case, the rectangles will end up with rounded corners anyway and so the result will be no different from using a 6mil polygon.

I did a quick google search, but couldn't find anything definitive on whether or not having a 3mil radius curve on all the corners of the antenna will make any difference (its only 0.07mm radius). However, I was looking at images of Bluetooth modules and many of them do in fact have noticeable rounded corners on the antenna line, like the example below. Granted in that example the curving is very pronounced - much larger than you would get from a 6mil polygon. On most of the pictures the rounded corners are much less obvious but definitely there.

BLE Antenna Image Source

  • \$\begingroup\$ I guess I will have to live with that. I am creating a BLE board trace antenna based on a reference design. The documentation states that I should follow the guidelines as closely as possible. It shows an antenna with right angles, so that is what I am hoping to achieve. I suppose the most important aspect of the antenna is its length, followed by the trace width and the shape. I doubt the ever-so-slightly curved angle will be all that much different than a right angle. What do you think? \$\endgroup\$
    – Stephen305
    Commented Feb 16, 2016 at 6:46
  • \$\begingroup\$ @Stephen305 I think you should edit the question to ask about rounded corners on antennas. Include a screen shot of the reference design. \$\endgroup\$ Commented Feb 16, 2016 at 11:51
  • \$\begingroup\$ @ScottSeidman I added the antenna reference design image. \$\endgroup\$
    – Stephen305
    Commented Feb 16, 2016 at 16:10
  • 1
    \$\begingroup\$ @Stephen305 I've added an update for something you could try. \$\endgroup\$ Commented Feb 16, 2016 at 16:33
  • \$\begingroup\$ Many thanks! That is a useful technique. I will probably just stick with 6 mil traces for the polygon and live with whatever effects the rounded corners cause. \$\endgroup\$
    – Stephen305
    Commented Feb 16, 2016 at 21:37

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