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)
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
EX        0        1        1        0        1        0        0
FR        0        0        0        0        f        0