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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!

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  • \$\begingroup\$ you asking about a Fractal antenna ?I have seen a java based simulator for that. \$\endgroup\$ Apr 27, 2012 at 15:08

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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
title: "Analysis and Design of an Inverted F Antenna Printed on a PCMCIA Card for the 2.4 GHz ISM band.pdf"

Wow Another inverted F design paper - looks superb

NO PCB antennas here BUT many432 MHz antennas

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    \$\begingroup\$ The third link is GIYF. Which isn't appreciated much here. \$\endgroup\$ Apr 27, 2012 at 15:23
  • \$\begingroup\$ @FedericoRusso - Many are likely to appreciate the retrospectively obvious but massively valuable insight that using images linked to web vastly improves the ability to locate pertinent information. I add such a link to many of my answers because I believe that it is nonintuitive BUT liable to vastly improve the value that people get from search engines. | EDITED 2022 to remove some snark :-) :-( \$\endgroup\$
    – Russell McMahon
    Apr 27, 2012 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, 2012 at 23:03
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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\$ Apr 27, 2012 at 16:51

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