40 m Vertical Antenna for the Maritime Lighthouse

40 m Vertical Antenna for the Maritime Lighthouse Amateur Radio Group (MLARG) By Bernie Cormier VE 9 BGC

What are we trying to accomplish when designing an antenna?

All the power should be radiated. The main RF lobe should be very low.

SWR of 1. 0 Resistance = 50 ohm Reactance = 0 Antenna will be in resonance

No power loss from loading coils, traps, feedlines or antenna tuner

Ideal Takeoff Angle? 50 degrees 40 degrees 30 degrees 20 degrees 10 degrees

Berlin at 6 degrees

Distance vs Take Off Angle • Antenna takeoff angle should be less than 15 degrees. • Antenna height above ground determines the main lobe. • Av ~ 10. 4 deg. Distance West East South 100 200 300 400 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 69 59 50 41 34 12 5 12 8 5 7 7 6 4 8 10 69 65 54 46 38 14 7 20 15 12 9 7 12 12 13 16 66 53 47 37 32 12 18 11 7 4 9 6 16 16

10 degree Main Lobe from a Horizon Antenna: 20 m = 95 feet 40 m =190 feet

20 m Pattern at 92 feet on Average Ground

How do you accomplish low main lobe for long range?

Only way is a Vertical Antenna by Salt Water

Horizontal Dipole

Vertical Dipole

Optimum 40 m Design

BLUE = Over Salt Water RED = Regular Ground

BLUE = My design over Salt Water RED = Vertical on ground with 8 radials

20 m Pattern at 92 feet on Average Ground

Design Requirements Fit in a Vehicle Self Supporting with guide ropes Pre-tuned to SWR 1. 0 Low radiation angle (less than 15 deg) Broadband 7. 0 -7. 3 Assembled by one person in 45 minutes

Feed point

Ferrite Beads (Balun)

Radials