The COSETI Observatory
Disadvantages of the microwave approach to SETI.
- Transmitter effective isotropic radiated powers (EIRPs) are relatively small, resulting in low received signal strength. Most of the power is wasted in empty space.
- Interstellar dispersion and scintillation effects prevent transmission of wideband signals. Different frequencies propagate at different velocities, and different frequencies fade at different times, thus corrupting a wideband signal. This one factor alone may be the major justification for the use of lasers.
- The sky is becoming noisier as navigational satellites, direct broadcast digital satellites and personal communication satellites are introduced.