Welcome !

This site may help you build an improved highly sensitive ADS-B receiver.
You need to have:
1. Knowledge and experience on building RF devices.
2. An L-band  RF Generator.
3. An L-band  Power Meter.
4. An L-band Dual Directional Coupler (optional-for tuning the antenna)

This is what my receiver looks like.

The antenna is active and detached from the receiver.