Increase the Range of IR

On the transmitting end: Increase the power of the transmitter; change the transmitter to a infrared laser diode (if it isn't already a laser); use an infrared lens to collimate the beam, if it is not a laser and not already collimated.

Similarly on the receiving end: Increase the gain of the receiver; use an IR lens to focus the IR signal onto the receiver; shield the receiver the receiver from extraneous noise (such as sunlight, during daylight hours) to minimize noise; cool the detector to minimize noise.

By increasing IR receiver sensitivity (hard way), increasing IR transmitted power (easier way), or by using an IR range extender that uses RF technology as intermediate (easiest way) and has the added advantages that it is commercially available and no visual contact is needed between transmitter and receiver. S.M.

Only use it at night.

What range do You have now?

What range do You need?

Using telescope mirrors you can extend range many times.