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When I design PCBs I always try to keep antenna as close as possible to the transceiver. Now due to the design I need the transceiver schematic on the left side but the antenna on the right side of the PCB. Can I connect the antenna "far" from the transceiver(of course the wire of the antenna's connection will be on the ground plane so the wire doesn't work as "antenna"). Would it be a problem if the antenna's wire(trace) goes under/over components and other wires(traces)?

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  • \$\begingroup\$ When doing these kind of designs you usually start with the antenna and then everything else will have to adapt. So how did you end up with it on the far side? \$\endgroup\$
    – Lundin
    Apr 13, 2021 at 6:50
  • \$\begingroup\$ cannot afford that big size of transceiver components and antenna.. \$\endgroup\$
    – Kris
    Apr 13, 2021 at 19:59
  • \$\begingroup\$ What does that mean? What IC are you using? Which antenna connectors? \$\endgroup\$
    – Lundin
    Apr 14, 2021 at 6:30

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As with all engineering problems -- that depends.

If you had a nice well-mannered antenna that presents a 50-ohm impedance (or any known, controlled impedance) at its terminals, then you could make a controlled impedance trace with that impedance back to the tranceiver. Then the only thing you'd have to worry about is the leakage from the trace, and the loss in the board. If you had a multi-layer board you could sandwich your trace between ground layers for much less leakage.

I would be careful about putting components close to the transmission line. If you're just using a single trace operating against a ground plane, then it'll have fringing effects that really never go to zero, but which probably drop off rapidly once you get further away than twice the width of the trace or twice the thickness between trace and ground plane, whichever is further. But the effects will never really go away -- so you wouldn't want to place sensitive components close to it (I'd build a board just for the experiment, and fire 433MHz through it and test how much various things placed at various distances picked up).

Without a lot of experimentation, I think that if I did do this I'd clear an avenue for the trace (perhaps along the edge of the board) and run it there. Or I'd just figure out how to place the tranceiver right next to the antenna, and bring the (presumably much slower) signals to and from it to wherever they need to be.

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  • \$\begingroup\$ Does clear avenue mean clear of components or clear of other traces also? For example left side is the tranceiver, right side the antenna (70mm distance), is it "ok..ish" to connect them with a trace on the top but have on the bottom other traces but clear of components? Of course the trace surrounded by ground plane \$\endgroup\$
    – Kris
    Apr 9, 2021 at 20:51
  • \$\begingroup\$ I would expect that as long as there's a ground plane between your antenna "hot" wire and whatever signals you're running through there, it's OK-ish. If you have your antenna feed line just one layer away from some other signal wire -- no, I don't think that'll fly. \$\endgroup\$
    – TimWescott
    Apr 9, 2021 at 21:09
  • \$\begingroup\$ so we are talking about more than 2 layers PCB.. 4 layers.. TOP layer antenna feed line, inner1 ground plane, inner2 and bottom wiring layers. is that what you mean? \$\endgroup\$
    – Kris
    Apr 10, 2021 at 9:01
  • \$\begingroup\$ Pretty much. With a 2-layer board you'd best route the feedline around a board edge, where it's neither splitting the board in two, nor cross-talking with other wires. \$\endgroup\$
    – TimWescott
    Apr 10, 2021 at 15:07
  • \$\begingroup\$ routing the feedline around the board edge would it be good though? I mean wouldn't it work then like antenna and not like a feedline since its not "deep" inside the ground plane? \$\endgroup\$
    – Kris
    Apr 10, 2021 at 20:28

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