 Hi, I'm Thomas with RF elements and welcome to another episode of Inside Wireless, today about path loss. Path loss is an attenuation of an RF wave as it travels away from the transmitter antenna. It is a measure of the illusion of the waves energy as it expands in the space. While the signal strength is decreasing with distance, path loss is growing and corresponds to the inverse of the signal strength. Path loss is part of Linn budget equation and it not only increases with distance but also frequency. Moreover, it grows exponentially due to the power of 2. Wisps often use 2.4 GHz spectrum because it is license free and the RF waves travel further than higher frequency signals. The 5 GHz spectrum, which is unlicensed as well, has somewhat higher path loss which can result in more hardware needed to cover the same area as with 2.4 GHz gear. The 60 GHz spectrum shows a great promise for future networks with gigabit speeds but has a much higher path loss which enables around 2 km length distance at best considering the state of the art of today's hardware. Path loss should definitely be considered while deciding which part of the spectrum to use but the decision goes well beyond simple physics of achievable distance. At 2.4 GHz the waves travel afar but the huge amount of other devices operating in the same bandwidth generates enough interference to clutter the spectrum making the network highly unstable and unreliable. At the same time the throughput speeds achievable in the limited bandwidth are increasingly insufficient for today's growing demand. At 5 GHz the path loss is about 7 decibels higher so the RF waves do not travel as far which can be an advantage acting as a natural protection against interference. But despite the shorter achievable distances the 5 GHz spectrum is quickly headed towards the same interference saturated state as the 2.4 GHz networks. At 6 GHz the path loss is about 28 decibels or about 700 times higher than at 2.4 GHz. Combined with the wide bandwidth available the possibilities for future multi-gigabit networks are vast but only in densely populated areas due to the shorter achievable distances which also makes for a naturally high security network. So which spectrum is the best for risk networks? There is no perfect solution that fits every situation. Every choice comes with a trade-off due to the principles and limitations just described. What is a strength in one place can be a weakness elsewhere and vice versa. But the awareness of the path loss and this short summary of the main properties can be a good starting point when designing your next link. Stay tuned to our social media channels for more interesting topics from the RF and subscribe to our YouTube channel.