Waveguides are metallic tubes usually used in transmission of radio waves. They are a good alternative to cables as waveguides can handle more heat and energy. On the other hand, they are not as physically flexible as cables.
The scientist from the fruit industry came up with another interesting application of waveguides: to determine fruit ripeness.
The concept is simple. Based on data collected over the years, scientist can determine the ripeness or perhaps even taste of a certain fruit based on it's weight, moisture (water) and sugar content. On the picking and packing conveyor belt, a wave guide is connected to a low power transmitter, beaming small radio signals to the fruit and then capture the radio waves that were reflected from the fruit. The computer can then estimate the weight and moisture content, then classify the fruit.
The development is difficult. Research in waveguides involve a lot of mathematical manipulations and modelling. The radio signals bounced back the fruit are not always easy to analyze. However, once a model is developed, the application is simple. Read more about this interesting use of radio signals online.