Antenna quests - End Fed Half Wave (EFHW)

Advantages

• Resonant antenna
• No need of radials/counterpoise
• Short feedline
• Only two contact points when deployed as a slopper
• Lightweight

Disadvantages

• Monoband (unless linked or trapped)
• Too long for vertical deployment
• High impedance, needs a transformer
• Resonance is affected by small deviations from the optimal deployment configuration

Deployment

Telescopic mast (6m), slopper configuration

[mast] ------ radiator ------ [transformer] --- coax --- [rig]

Transformer

For some reason, the classic 49:1 did not work for my setup for the 20m band. It gave me about 80Ω impedance and the lowest possible SWR was 1:1.7. I changed the transformer to 81:1 (3 primary, 9 secondary turns) and it helped a lot. The impedance went very close to 50Ω and the SWR was less than 1:1.2 for the entire CW portion of the band. malen, VE6VID who have me the parts to build the transformer commented that this higher ratio transformer works better for 10-20m bands and the lower ratio transformer works best for 40-80m bands.

Further experimenting

Try to do a linked radiator for 17 & 20m