Notes on Physical/Electrical Problems This widely used standard gain horn is a powerful demonstration of the importance of discovering and solving a variety of physical and electrical problems, obvious or hidden. According to mainstream standards, the gain factor can be calculated based only on the size of the horn aperture. In practice, however, there are at least two problems with this simplified approach: the horn itself may be damaged; and the waveguides connected to the horn (eg, cable connectors, internal components, etc.) may have physical or electrical problems. To characterize a waveguide, we need to connect two waveguides (the performance of one waveguide is known and the other is unknown) and measure the insertion loss.