As the resonant frequency of a trap is lowered relative to the operating frequency, the required length of the trapped section grows shorter. 1.98 63.56 - j0.72 Note that the high band feed impedance rises and the low band feed impedance falls relative to a standard dipole. The 10 meter dipole gain is down from the standard by 0.1 dB, while the 20 meter dipole gain is down by 0.15. The decrease in gain on 20 meters is due mostly to a combination of the shortening of the dipole from its standard length and to trap losses. We can roughly sort these losses.
Similar trends show themselves with the copper wire antenna.
However, the losses at 10 meters are unexpectedly high. The 10-meter model was ,of course, double checked for error. The program shows nearly a 0.5 dB power loss within the loads of the wire antenna, far above the loss of less than 0.1 dB for the same traps in the aluminum dipole. It is also useful to examine the current distribution in a trap antenna. Current maxima are not to scale to save drawing space and to clarify a few matters.