[Antennas] Vertical matching for 40m

[Hungaerotech]

Dear Friends,

I have a 26 m vertical, which I am using on 160 and 80 meters as well. I am
trying to match it for 40 m as it is close to 5/8 wave on 40.

My calculations show that the antenna impedance is something like 110-j350
ohm. (Is this correct?)

The antenna is 26 m tall, average diameter is 8 cm, and is fed with 50 ohm
coax. I have some 80 radials which are 15 to 60 m in length. I think the
radial system represents a ground loss of 7 to 8 ohms. (Is there a way to
measure it?)

I designed a matching network, which consists of a 150 pF series capacitor
and a 5.5 microH shunt inductor.

But guess what? The antenna resonates on 6.2 and 8.3 MHz, and has an SWR of
5:1 on 40 meters.

Could someone with the appropriate software check if my calculations are
good or did I make a big mistake somewhere?

73 es DX

Steve HA0DU