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I'm trying to build a Radio wave penetration device that register the RSSI on the RX module. There are two 433 transceivers one is the RX and the other TX - I want to place between them different types of walls to measure the penetration of the radio wave.

To avoid other signals to interfere and to assure maximum penetration I want to use for the both a directional antenna. The catch is it must be as small as possible I've googled for hours trying to find small designs but no luck - I'm not going to transmit any data I just want a link and a RSSI read. any Ideas? I need it ( the antenna ) to fit a 12X12 cm box.

Thanks

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  • \$\begingroup\$ What is the desired gain of the antenna? You can make is as small as you want but the gain will be low. \$\endgroup\$ Apr 9, 2015 at 3:07
  • \$\begingroup\$ As I said I'm not transmitting any data - just want to penetrate as much as I can and get a RSSI read on the other end I'm not sure what is my bottom gain limit \$\endgroup\$ Apr 9, 2015 at 3:13
  • \$\begingroup\$ You are not going to find a directional (high gain) antenna that operates at 433MHz and fits in a 12" box let alone a 12cm box. Lower your expectations. Also it's "MHz" not milli hz \$\endgroup\$
    – Andy aka
    Apr 9, 2015 at 7:39

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You are going to find it difficult to come up with any truly directional antenna that small for 433 MHz. That is basically the 70cm band, so a full wavelength is going to be 70cm. Even a shortened loaded yagi type antenna won't fit in your box.

About the smallest, efficient, directional antenna I can think of would be the Moxon design, but even that is too big for your application, by a great amount.

Your best bet would probably be to just use a standard "Rubber Ducky" antenna mounted to a BNC fed through the box.

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How about a chip antenna, like this one, its about 0.5"x 0.36"x 0.1"

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  • \$\begingroup\$ The only problem is that its not directional and it need a " associated ground plane counterpoise" which I don't know what it is. \$\endgroup\$ Apr 9, 2015 at 4:33

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