A High - Q antenna is a radiator with the length under 0.2*lambda. It has a high-Q inductor to compensate the parasitic capacitance of the shortened wire or to make the antenna electrically longer than its physical length. A high-Q antenna is a compromise when there is no space to deploy a dipole or a monopole. It is known as screwdriver antenna and is working with the ground-plane (upon the top metallic ceiling of the car) as a quarter-wave monopole. It has a very poor efficiency below 10%. Don't use it at high power or you can put your equipment in jeopardy.
Below is the source code in 4NEC2:
CM Design by Nicolae Crisan - YO5OUC
CM 09 February 2016
CM Resonance at 3.6 MHz
CM More details at http://antennex.com (antenneX Issue No. 227 - March 2016)
CE
SY f=3.6 'the frequency in MHz
SY A=1.7 'overall antenna length in meters
SY B=0.5 'the distance from the base to the loading coil in meters
SY D=0.003 'diameter of the radiator's wire in mm
SY L=258e-6 'Off load inductance in H
SY R=8 'series loss resistance of the coil
GW 1 2 0 0 0 0 0 B D/2
GW 2 6 0 0 B 0 0 A-B D/2
GE 1
LD 0 1 2 2 R L 0
GN 1
EK
EX 0 1 1 0 1 0 0
FR 0 0 0 0 f 0
EN
