https://devzone.nordicsemi.com/f/nordic-q-a/13176/what-is-nrf51-dk-antenna-s-name-or-application-noteHi Nordic Community, Could you please tell me what is the antenna reference design used in the nRF51 DK? and why a lot of BLE development boards (like Redbear BLE shield ) use this type of antenna instead of using the Inverted-F Antenna(IFA)? Aen-USTelligent Community 13Thu, 14 Apr 2016 13:14:26 GMThttps://devzone.nordicsemi.com/thread/50229?ContentTypeID=1Thu, 14 Apr 2016 13:14:26 GMT137ad170-7792-4731-bb38-c0d22fbe4515:ed501bc9-b320-486b-a04a-830534d44dfcFormerMember<p>The antenna on the nRF51 DK is a quarter-wavelength monopole antenna, and it is described in <a href="http://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.whitepapers%2Fdita%2Fwhitepapers%2Fpdflinks%2Fnwp_008.html&amp;cp=11_11">this</a> whitepaper.</p> <p>An inverted-F antenna (IFA) is a quarter-wavelength monopole antenna (1/4-wavelength antenna ) where the additional&quot;F&quot;-part represents a tuning component. For a regular 1/4-wavelength antenna that tuning component is the physical parallel component nearest the antenna.</p> <p>The value of the tuning component has to be found during tuning, because the antenna impedance depends among other of the environment of the antenna; two identical 1/4-wavelength antennas may require different values of the tuning component because they are used in different designs, different housing, and different environments. Therefore, it is a lot easier to tune a &quot;regular&quot; 1/4-wavelength antenna than an IFA antenna. Theoretically, you would need to adjust the &quot;F&quot;-part of the antenna for the various tuning measurements.</p><div style="clear:both;"></div>