I dont know why people continue to buy those horrible ASK radios when for around the same price you can get these.https://www.aliexpress.com/item/HC-11-HC11-433MHz-wireless-RF-serial-UART-module-CC1101-5V-3V-AT-command/32424814620.html?spm=2114.search0604.3.1.338652308IoyY4&
I thank you all for your answers.my problem has been solved by program (#include <RH_ASK.h>), and the subject is closed (I got communication!) about "missing coil".+by the way, Without Antenna it's working/communicating from 1cm to 8m in free air!
So the coil is used on some modules as the antenna right? While other modules that look similar use a different structure (not coil) as the antenna .... and that antenna is already built-in with the module, right?
No, the coil is not designed to be used as the antenna on these modules. However, there is sufficient RF energy leaking that a receiver at close range can detect the signal in spite of not having a proper antenna.