This is my first post; sorry if I've unwittingly broken any rules or accepted conventions around here...

I'm using a Pulse Engineering W3011 ceramic GPS antenna. As is common with these small ceramic antennae, the feed and GND share a pad on the part. Without knowing what the internal structure of the antenna looks like, I can't tell if it's important that the feed-line connects to a certain region of the pad and the GND to a different region, or if the connections are interchangeable.

Referring to the figure below, observe that feed and GND (traces 1 and 2) both connect to the same metallized pad on the chip antenna. Now imagine that I've drawn the same copper pattern, but on the reverse side of the PCB, and we're looking at the layout on the computer screen, as one would do in your favorite EDA software. In other words, we're looking through the PCB so that when you flip the PCB over, the feed-line is entering the part from the left. So far, this is permissible because Pulse states that pads 1 and 2 on the part are identical and the part can be mounted either way. But the question I have is whether or not it's OK that the feed-line is hitting the pad in a different place than is stated in the document.

In other words, with the antenna placed on the copper as in the diagram, with antenna pad 1 on the left and 2 on the right and the copper on the top side of the PCB, the feed-line hits the top corner of pad 2 on the antenna. With the antenna flipped around so that antenna pad 2 is on the left and pad 1 on the right, it's really the bottom of antenna pad 1 that touches the feed-line. But if the copper is on the bottom side of the PCB, it's the top corner of antenna pad 1 that touches the feed line (or the bottom corner of antenna pad 2).

With that exhaustive explanation out of the way, does anyone know if it matters where on the pad feed and GND touch and, furthermore, if the positions can be swapped? I understand the basic concept that one side of the antenna forms a PIFA-type radiator, the other side connects to ground, and the slot in the surface between the two capacitively couples the two elements. But I just don't know how dependent the proper operation of the antenna is on the relative positions of feed and GND.

From W3011 data sheet

  • \$\begingroup\$ I recently had a similar question about another of their antennas. I contacted them, and they had additional documentation not available online. It was pretty helpful. Their email address list is here, but I got a faster response be calling my area representative, who quickly got a hold of the right person for me. A link to a list of Reps can be found to the right of the Contact webpage. Good luck :) \$\endgroup\$ – bitsmack Dec 23 '14 at 19:20
  • \$\begingroup\$ The datasheet says 'Antenna is symmetrical. Either of terminals 1 or 2 can be feed / GND' \$\endgroup\$ – Lg102 Apr 29 '15 at 7:10

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