Hexagonal barium ferrites have wide applications as anti radar filler in coatings and other composites. M type barium hexagonal ferrite (BaFe12O19) has been synthesized by citrate sol gel auto combustion method using barium nitrate and ferric nitrate as sources for cations and citric acid as fuel. The effect of cations to fuel ratio were studied using ratios of (1:1, 1:2, 1:3) with solutions at pH 7 in all cases. The effect of calcination temperature and calcination time were studied in the range 850ºC – 1000ºC and 3 – 6 h respectively. Prepared samples were characterized by FTIR, XRD, TEM and SEM. Reflection losses of the prepared samples in the frequency range X and Ku bands (8-18 GHz) were measured. The results show that cations to fuel ratio of 1:2 show the formation of hexagonal barium ferrite with nano size particles. Calcination temperature of 950°C for 5 h calcination time give the best radar absorption in the X and Ku frequency bands with maximum absorption of 62.17% at 12.1 GHz.