If so, how can this be accomplished?
I am unaware of any RFID system that uses low-frequency (LF) signals to achieve that kind of read range. RuBee is a form of active RFID that employs LF, but it operates at 131 kHz, and the read range is approximately 100 feet. RuBee has some advantages over other types of active RFID systems that utilize higher frequencies, but longer read range is not among them.
My guess is that it is impossible to achieve a read range of 1 kilometer (0.6 mile) with a 20 to 50 Hz system, because if that were possible, some companies would likely offer such a system. Perhaps some of our readers who are RF engineers might be able to shed more light on this subject.
—Mark Roberti, Founder and Editor, RFID Journal