Can anyone provide a reference design for a 434 MHz PCB Trace Antenna? Is it just a matter of creating a snake trace pattern about 17cm long and slapping a ground plane under it (with a trace thickness for say 50 ohms characteristic impedance to the ground plane given the PCB thickness)?

The context is that I think I'm heading toward using a trace antenna with the RFM12B transceiver module en route to passing regulatory standards. I've been told that embedding the antenna in the PCB is an easier / lower cost path to certification than allowing for a whip (or other externally connected) antenna. Any advice or pointers would be most appreciated!

  • \$\begingroup\$ you asking about a Fractal antenna ?I have seen a java based simulator for that. \$\endgroup\$ – Standard Sandun Apr 27 '12 at 15:08

Tye following may be useful. Most are 2.4 GHz focused but should provide some useful ideas.

TI 2.4 GHz PCB Antenna - AN 043 - 2.4 GHz but should have significant value.

Compact Integrated antennas - Freescale AN 2731 - significant relevance

A few zillion PCB antennas - all images linked to webpages

Commercial products - but some good idea starters

Inverted F design - 2.4 GHz but significant relevance

Wow Another inverted ed F design paper - looks superb

NO PCB antennas here BUT many432 MHz antennas


144/432 diplexers

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    \$\begingroup\$ The third link is GIYF. Which isn't appreciated much here. \$\endgroup\$ – Federico Russo Apr 27 '12 at 15:23
  • \$\begingroup\$ @FedericoRusso - your brain may see it as GIYF, and you may not appreciate it, but others very very probably do not in all cases see things as your brain does (or mine) and with certainty some will appreciate the retrospectively obvious but massively valuable insight that using images linked to web vastly improves the ability to locate pertinent information. As I add such a link to many of my answers BECAUSE I BELIEVE IT IS LIABLE TO BE OF GREAT VALUE TO PEOPLE AND ALSO INOBVIOUS TO MOST then you might as well get a rubber stamp and stamp all my answers that way. No? \$\endgroup\$ – Russell McMahon Apr 27 '12 at 22:47
  • \$\begingroup\$ @FedericoRusso - please to see the response that I have added to the question which you cite above. As noted t here, a modicum, or even a soupcon, of common sense is required. \$\endgroup\$ – Russell McMahon Apr 27 '12 at 23:03

From this document:

One big advantage for the short whip is that it can be a trace on a PCB, with a chip inductor used to tune out the capacitive reactance of the antenna. If the trace runs parallel to ground, the real part of the antenna impedance will be approximately 10 ohms. In a hand-held unit, the impedance will be raised substantially through hand effects. For a tenth wavelength strip on a board with hand effects included, the antenna has a capacitive reactance of about 150 ohms. At 433.9 MHz, this would require a 56 nH inductor to cancel the capacitive reactance of the 2.7 inch (70 mm) long line.

enter image description here

The document also describes spiral, chip and loop antennas (a.o.).

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  • \$\begingroup\$ Is that software defined antenna's are on the market ? \$\endgroup\$ – Standard Sandun Apr 27 '12 at 16:51

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