Using a magnetic mount for HF portable communication
Mag mount connection to vehicle You can measure your magnetic mount’s coupling to your car. Since there is no direct dc connection the coupling is through the capacitive reactance. The capacitor consists of two parallel plates, one being the bottom surface of the magnetic and the other the metal surface of the vehicle directly under the magnet. You can calculate the capacitance using the formula in the ARRL handbook. However that will not be very accurate as you need to know not only the spacing but the value of the dielectric between the two plates. That dielectric is of the vehicle’s thin layer of paint and whatever the covering is over the magnetic to keep from scratching the paint. I find it easier to measure with an inexpensive meter that will read capacitance. It is easy if you have two identical mag mounts as no connection to the vehicle is needed. With that setup you have what amounts to two identical capacitors in series. The capacitance of one becomes simply twice the v...