Take into account layout considerations for RF There are a number of layout considerationg when designing RF systems that were not taken into account or not quantified when making the first design. - transmission line width The microstrip [1] transmission line connecting the balun and filter circuit with the antenna must be impedance-matched with the antenna. The rule of thumb according to [2] is to make its width twice the board thickness, in this case 0.8 mm or 31.5 mil. The microstrip calculator at [3] also takes into account the thickness of the copper, 1 oz, and yields a slightly narrower 57.5 mil or 1.46 mm. A more elaborate calculator can be found at [4]. - via spacing Section 4.2 of [5] recommends a via spacing of no more than Lvia = C/sqrt(Er)/Fres where C = the speed of light, 3*10^8 m/s Er = the board's dielectric constant, 4.5 for FR-4 Fres = the resonance frequency, at least 24.5 GHz We thus obtain Lvia = 5 mm. - component placing [5] places DC blocking, balun, and filter close to the transceiver, with only the feed line between the RF circuit and the antenna. Thus, no changes are needed. - feed line termination Point 12 of [6] warns us that we may need to terminate the transmission line if it is longer than 20% of the signal's rise time. Point 1 of [6] gives the rise time as 1/(10*Fclk), which looks as if it's meant for digital signals. But we'll use it anyway. [2] gives us the typical propagation delay for a microstrip as 150 pS/in. This means that Lmax = 0.2*tr*v with tr = 1/24.5 GHz v = 1 in/150 pS We thus obtain Lmax = 1.4 mm [2] suggests that the maximum unterminated stub is L(in) = tr(nS). With tr = 1/(10*Fclk), we thus obtain Lmax = 1.04 mm. Not sure if all this even applies to antennas. This needs looking to by someone who understands about RF. [1] http://en.wikipedia.org/wiki/Microstrip [2] http://www.hottconsultants.com/techtips/rulesofthumb.html [3] http://www.cepdinc.com/calculators/microstrip.htm [4] http://mcalc.sourceforge.net/ [5] http://www.ti.com/litv/pdf/swra236a [6] http://www.pcbmotif.com/home/index.php?option=com_content&view=article&id=104&Itemid=137 Conclusion: the antenna feed line needs to be revised. The via spacing of the RF area needs to be examined. The recommended spacing may be beyond the capabilities of a DIY process, though.