Yes, the wider spacing at one end is to reduce the parasitic inter winding capacitance at higher frequencies (> 10 MHz). This winding to winding capacitance effects the self resonance of the inductor making it less ideal at these higher frequencies.
Gary K5AMH On 6/25/2022 11:14 AM, Michael Giannaccio via BVARC wrote:
This is probably a basic question but I’ve come up empty in my search and can’t seem to find the answer in the Antenna Book. Can someone explain to me or link me to some reading as to why some roller inductors and screwdriver antennas like the ATAS have less turns per inch on the ends of the coil and more towards the center? I do have the latest edition of the antenna book so if it’s in there I can look it up. Thanks! 73, Mike Giannaccio W5REZ ________________________________________________ Brazos Valley Amateur Radio Club BVARC mailing list [email protected] http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.orgPublicly available archives are available here:https://www.mail-archive.com/[email protected]/
-- Gary Sitton, K5AMH [email protected] SDR/DSP Consultant, "Have FFTs, Will Travel."
________________________________________________ Brazos Valley Amateur Radio Club BVARC mailing list [email protected] http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org Publicly available archives are available here: https://www.mail-archive.com/[email protected]/
