2. Increase transmit power
This is usually restricted by the FCC in whatever standard you use. Just use the max you are allowed. Sometimes the chip companies make chips that run at less power than allowed, so you may have to add an external power amplifier (PA) later. Wi-Fi chips and modules are like this. And Bluetooth has three power level options.
3. Increase receiver sensitivity
Receiver sensitivity is a measure of the gain the receiver has. It is usually expressed in dBm. Typical IC receivers have sensitivities in the -80 to -115 dBm range with the higher dBm value being the most sensitive. Choose a chip or module with the greatest sensitivity if maximum range is one of your key design goals.
4. Use an LNA
Most IC receivers already contain some kind of low noise amplifier front-end. But you can boost receiver sensitivity by adding an external LNA between the antenna and the IC input. Just be darned sure that this LNA has the lowest possible noise figure or you may be hurting yourself more than you are helping if the noise kills the signal.
5. Reduce transmission line losses
If your system uses a coax transmission line between the antenna and transceiver, be sure to use the lowest loss line you can find. Most wireless systems have short transmission lines, but at the normal UHF and microwave frequencies, coax has enormous losses. You have no idea until you take a look at this. Even a few feet of line can drop transmitted and receiver power by many dB. Shorten the line as much as possible or use a better, lower loss line. Or if you can, put the transmitter and/or receiver at the antenna.
6. Use directional antennas
A directional antenna focuses the radiated power in one direction. Such antennas are said to have gain. It is a way to get a power boost without actually increasing the transmitter power, and it increases the level of the received signal. The formula above clarifies just how important this is. Just be careful not to violate FCC rules, as some regulations do not allow gain antennas. Check the FCC CFR 47 Part 15 for applicable rules.
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