“fan region” around $\ell\approx140^\circ$, $b\approx8^\circ$, which has an extended polarized component of about 3 K [@1973MNRAS.163..147W]. Such a region could produce a ripple in the measured spectrum from a single linear polarization as the polarization angle rotates with frequency. Under the worst circumstances, if such a region were located at the peak of the EDGES beam, the magnitude of the ripple could reach $\sim50$ mK. Away from the Galactic plane, however, where EDGES observations are generally targeted in order to reduce the system temperature, it is more likely that the effects of polarization would be at least an order of magnitude lower. Furthermore, if the rotation measure (RM) is of order 10 rad m$^{-2}$, then the polarized component could be averaged out over $\sim1$ MHz. Nevertheless, in future versions of EDGES, both ports of the antenna will be sampled in order to check for polarization effects and other systematic effects that result from the non-uniformity of Galactic radiation.

A dipole antenna is naturally a balanced electrical system. To convert from the balanced antenna leads to the unbalanced receiver system (in which one lead is grounded), a short coaxial cable enclosed in a clamp-on split ferrite core with a high impedance 