This circuit uses a diode as a radiation sensor. The operational ones are old because the publication is from the 80's, but modern low voltage equivalents can be tested.
Antenova Grandis antennas can be purchased from Mouser Electronics for frequencies from 868 MHz to...
The CMOS TLC555 [equivalent to the bipolar 555] can be used as a monostable in the configuration...
The configuration shown in the figure allows you to implement an debounced switch with CMOS or TTL...