When propagating in air intense femtosecond laser pulses organize into intense self-guided light pulses. In turn, such self-guided pulses generate in their wake extended thin plasma columns. We show that these plasma columns act like antennas able to radiate electromagnetic pulses.
For the first time we connect two filaments created in air by two femtosecond laser pulses. For a specific time ordering of the pulses a twofold increase of the total filament length is achieved. The direct benefits include improved air plasma conductivity and stronger continuum generation.