Before you can design an RF Electromechanical Switch, it is necessary to understand the difference between how signals propagate in a DC (direct current) condition compared with an RF condition.
In the RF switching system since the routed signals (on the transmission line) in DC condition is at low frequencies with constant voltage or current, signals at different points on a coaxial cable change minimally. By contrast, the routed signals in RF condition vary along the frequency as they go higher.
Another question you may ask: “Does DC have frequency?” The answer is NO. However from mathematical perspective, it does have a frequency which is 0Hz.
Since the RF signal wavelength is shorter in comparison to the length of the coaxial cable, thus multiple cycles of the signal simultaneously propagate through the coaxial cable. As a result, the amplitude of an RF signal varies (since it is a wave), while it is constant for a DC signal.
Compensation for signal degradation due to RF signal reflection and power losses must be taken into account when dealing with RF signals. In addition, as a switch matrix system cascades switches at least two levels, these RF characteristics increase in relation to each other and deteriorate the overall system performance, unless resulting tradeoffs are understood.
