20 Meter Loggi I
first chose to look at creating a Loggi for the 20 meter Amateur
band. After a quick look at available large commercial 20
meter Yagis, I chose the M2
20M6 Yagi
as my "standard" to compare to.
My first attempt produced an 8-element Loggi on a 65 foot
boom which produced 11.2 dBi peak gain and over 25 dB F/R across the
14.0-14.35 MHz band. My second attempt produced a 7-element Loggi
on a 56 foot boom with 11.27 dBi peak gain, more than 11.0 dBi
from 14.0-14.35 MHz and 26 dB F/R (peak) and more than 22 dB F/R across
the band. I first optimized the design in NEC2 with
linear-taper elements, then converted these to a standard element-taper
based on Hy-Gain 20 meter diameters. The tapered-diameter
design was simulated in NEC 4.1. The plots are shown below. Here
is the NEC2 file. I can supply a NEC4 file upon request.
