Wireless is radio - "low frequency" is the kicker. Standard AM tops out at 1.5MHz, amateur shortwave or HF reaches 30MHz (HF CB Radio). That gives to 2 approaches. First Approach: Get a fast Analog-Digital Converter (ADC) chip. Linear Technology and Texas Instruments have ADC's running at 65M samples/sec (Msps) . Once the RF is in the FPGA, use DSP techniques to isolate the frequency you want. Problem: the pre-built Dev Kits with a suitable ADC are NOT Cheap! Second Approach: Make a basic converter to get a section of RF down to near DC. You can use slower ADC, but due to the vagaries of mixing you will have "negaive" or host channels unless you add a second ADC. Look up "IQ" sampling for more details.