Radar Cross Section (why -30dB) ?

Hi friends,

Can anybody help me regarding the Radar cross section or back scattering signal limit like I am getting S21 plot for an RFID tag with a scale of below -30dB in references also they shown the same but no one justified it...may I know the reason limit of RCS.

1/1000 of power? Nice round (small) figure!
Frank

This is the ratio of aperture relative to a 1m2 target like a human.

Hi,

can you explain me some more clear...

Ok Wiki has some other examples

Radar Cross Section is a combination of reflectance and absorption measured relative to a 1m2 response to mm RADAR.

A Cargo Ship +20dB or 100m
A human 0dB
A bird -20dB
an insect -50dB

Perhaps a suitable reference for an RFID is thus ~ -30 dB

Thanq somuch sir, I got it, I am doing research on RFID tags but my total tag result as shown in image, the level is -30dB i.e., S21 so how can I justify it. like can i cal it as an antenna isolation?.