  To probe the cosmic particle flux at the highest energies, large volumes of
dense material like ice have to be monitored. This can be achieved by
exploiting the radio signal. In this work, we provide a macroscopic model to
predict the radar echo signatures found when a radio signal is reflected from a
cosmic-ray or neutrino-induced particle cascade propagating in a dense medium
like ice. Its macroscopic nature allows for an energy independent run-time,
taking less than 10 s for simulating a single scatter event. As a first
application, we discuss basic signal properties and simulate the expected
signal for the T-576 beam-test experiment at the Stanford Linear Accelerator
Center. We find good signal strength agreement with the only observed radar
echo from a high-energy particle cascade to date.
