Sailor VPA 30 AM-FM
The SAILOR VPA 30 is an active omni-directional antenna optimised for AM reception from 0.1-30 MHz with vertical polarisation.
The electronics perform a two stage impedance transformation between the E-field at the rod and the 75 ohm cable. A Ka value of 0.16 means that at all frequencies, the antenna is as efficient as a full size dipole. The design of the complete antenna is made in such a way, that for most of the listening time (day-night and seasonal variations) the external atmospheric noise, masks the noise generated by the electronics.
The design is fine tuned in this respect and neither the rod diameter nor the rod length should be altered. Power is fed to the antenna via the coaxial cable, which floats with respect to ground at the antenna end, except for a 3nF/3 kV decoupling capacitor between the coax shield and body. The circuit has adequate protection against lightning and there are no serviceable parts inside which require access for maintenance.