If you save it to your hard drive, double-click the file name from Windows Explorer (Right-click Start then left-click Explore to start Windows Explorer) and it will run.

Click this link TwinTrap then click Open to run from the web or Save to save the program to your hard drive. This program is self-contained and ready to use. Run this Program from the Web or Download and Run it from Your Computer Slowly vary the frequency and search for a very sharp peak in impedance magnitude to find the resonant frequency. The resonant frequency is best checked with a one or two turn loop of thin wire around the centre of the trap with a 6-inch long pair of wires to an antenna analyzer switched to its impedance range. Polyethylene and Teflon are the best insulants in high-power applications. In engineering, the word bifilar describes wire which is made. Large-diameter wire or bifilar wire (two parallel wires) can provide high efficiencies but is costly and can result in thick Rx-coil designs. A bifilar coil is an electromagnetic coil that contains two closely spaced, parallel windings. Make the diameter over the wire insulation roughly two or three times the wire diameter. The choice of wire gauge for the Rx coil is based on cost versus performance.

Some bifilar-wound coils have adjacent coils in which the turns are arranged so that the potential difference is magnified (that is, the current flows in the same parallel direction). This can be achieved by winding coils using two insulated conductors. An overall length/diameter ratio in the range of 1.5 to 2.5 is recommended. A bifilar-wound coil is one that contains two closely spaced, parallel windings. A high-voltage, high current, tuning-capacitor is not needed. The inductance resonates with the distributed turn-to-turn capacitance at the trap frequency which is set to the exact value desired by adjusting fractional coil turns. The two wires are then connected series-aiding. T wo identical plastic-insulated wires are wound together on a former (as with a bifilar RF choke). No traps have been connected in an antenna for performance checks. Only one trap of this kind has been constructed and measured by the author as a check for program errors. Note: This program should be considered experimental. Bifilar-Wound Antenna Traps Author: R.J.Edwards G4FGQ © 1st August 2002

Bifilar coil design