# W (The bandwidth of the SAR signal and The range to the object on ground

Dear all,
I want to calculate B⊥, crit for Sentinel1A. As I know its formula is:

B⊥, crit = − (W ρ λ tan(θ − α))/c

c: The speed of light,
W: The bandwidth of the SAR signal,
ρ: The range to the object on ground,
λ: The wavelength of the SAR signal, (λ=0,055m)
θ: The incidence angle,
( Incidence angle range for interferometry mode (IW): 29.1° - 46.0°
incidence angle for IW2 is from 36.47 to 41.85.)

α: The local surface slope (as I am working on ice, it is zero)

My Question:
I know all parameters for Sentinel1A except W (The bandwidth of the SAR signal) and ρ (The range to the object on ground).

Is there anyone can guide me?

Cheers,
Marjan

The range-bandwidth for the various modes and beams can be found in this document:

https://sentinel.esa.int/documents/247904/1877131/Sentinel-1-Product-Definition

The range to the ground you can calculate yourself from orbit altitude, incidence angle and Earth radius.

Dear mengdahl,
I found that :
The bandwidth of the SAR signal is 48.3 Hz for my case (IW2, Range Look Bandwidth [Hz]) and I used below formula for calculating ρ (The range to the object on ground). Please look at it. Is it OK?

The range to the object on ground (ρ) = Satellite height (693000m) cos (mean incidence angle in IW2= 39.16) = 0.775