Donor Antenna Isolation Calculator (ERRCS/BDA)
Check measured donor-antenna isolation against BDA gain before the oscillation finds you. Enter your sweep result and gain setting — the margin and verdict update instantly and the URL is shareable as-is.
Enter measured isolation and BDA gain to check the margin.
The required margin is jurisdiction policy — verify the value your AHJ enforces before relying on this result.
What this checks & why
A BDA amplifies whatever reaches its donor port — including its own output leaking back from the inside antennas. If the isolation between the donor antenna and the DAS does not exceed the BDA’s gain by a healthy margin, the system feeds back on itself and oscillates, jamming the very channels it is supposed to protect.
The check is simply margin = measured isolation − BDA gain, compared against the required margin. Many jurisdictions require at least 20 dB of headroom; some require more, so the margin field is editable. A margin exactly at the requirement passes.