Complex sentence: Radio observatories are similarly located far from major centers of population to avoid electromagnetic interference (EMI) from radio, TV, radar, and other EMI emitting devices, but unlike optical observatories, radio observatories will be placed in valleys to further shield them from EMI.
Split into simpler sentences: Radio observatories are similarly located far from major centers of population to avoid electromagnetic interference (EMI) from radio, TV, radar, and other EMI emitting devices. But unlike optical observatories, radio observatories will be placed in valleys to further shield them from EMI.