MFJ Enterprises Original MFJ-931 1.8-30 MHz HF Artificial RF Ground. MFJ-931 creates an artificial RF ground! It resonates a random length of wire thrown along the floor and produces a tuned counterpoise. This ground effectively places your rig near actual earth ground potential even if your rig is on the second floor or higher with no earth ground possible. Also, the MFJ-931 electrically places a far away RF ground directly at your rig -- no matter how far away it is. It reduces the electrical length of the ground connection wire to virtually zero by tuning out its reactance. The MFJ-931 connects between your rig and a random length of wire or a connecting ground wire. Its tuned for maximum ground current using the built-in RF ammeter. The MFJ-931 Artificial RF Ground covers 1.8 - 30 MHz and measures a compact 7.5W x 3.5H x 7D inches.