  The dielectric behavior of half doped manganites La0.5Ca0.5-xSrxMnO3 (0.1
\leq \times \leq 0.4) with varying magnetic ground states has been studied. The
real part of relative permittivity as a function of temperature
{\epsilon}^'(T), exhibits a maximum around the ferromagnetic (TC) and charge
ordering transition (TCO) temperatures accompanied with high dielectric losses.
The activation energies obtained for x = 0.1 and 0.3 samples below TCO are the
same ~ 0.12eV, whereas the relaxation time constant varies in the range 2.8
\times 10-9 s - 6.03 \times 10-11 s. In contrast to samples having x \leq 0.3,
for x = 0.4 doping the dielectric permittivity exhibits a strong temperature
dependence in the vicinity of magnetic phase transitions. This behavior may be
correlated with the presence of competing magnetic interactions (magnetic
polarons) close to the magnetic transitions.
