Public Ideas — I know radio communication well and I’m building an advanced receiver. Who could help me design the circuit?

Nice project. Before picking an IC, pin down three numbers: frequency range, channel bandwidth, and the weakest signal you want to hear (sensitivity). Then: for flexibility, an SDR front end is the easiest path (RTL-SDR/R820T for a cheap start, AD9361/AD9363 or LMS7002M for serious wideband work). For a single band, a dedicated chip like the Si4735 (AM/FM/SW) or an SX127x/CC1101 (sub-GHz digital) is simpler. Whatever you choose, sensitivity is mostly decided before the chip: a good LNA placed right after the antenna, a band-pass filter in front of it, and a clean, well-shielded supply. Happy to look at your requirements and sketch the block diagram if you want.

Could you describe one real situation where the receiver should outperform what you already have? That would give a circuit designer a practical brief. A local radio club could help compare the prototype against existing equipment and might become a partner for a build workshop.