5/8λ Ground Plane for 6M (50MHz) - G4CQM

5/8λ Ground Plane for 6M (50MHz)...

5/8λ Ground Plane for 6M (50MHz)

For those Radio Amateurs lacking space to install a full size 50MHz beam, then this 5/8λ Ground Plane design offers a simple and very effective antenna solution. Whilst some Internet critics fail to grasp, matching is made easy in the design process when using K6STI's AOP and symbolic dimensions. Along with the K6STI Single-Layer Air-Core Inductance Calculator!

Mounted at 6M Above Ground Level (AGL) delivers a low angle of radiation (Radiation Peak at 8° Elevation) is best for DXing!

With this particular design the four radials are of fixed length at 1495mm each using 1/2 Inch (12.7mm) OD tube. The driven element (also fixed length) is tapered (two sections), the lower some 2M in length and of 3/4 Inch (19.05mm) OD tube. Meanwhile the top section is 5/8 Inch (15.875mm) OD tube and protrudes 1759.5mm above the lower section.

A small air spaced inductor of 564nH is connected at the base of the driven element. This can be fabricated using 10 gauge (2.5882mm) copper wire wound to the following dimensions: 1/2 Inch (12.7mm) diameter and 1 Inch (25.4mm) long with approximately 7.5 turns. This is the only part requiring experimentation/adjustment to obtain lowest SWR at 50.150MHz.

With this arrangement 50Ω coaxial cable can be wired directly, inner to the inductor base, and outer braid to the radials. Keep connections as short as possible!

Antenna File

Air Spaced Inductor Dimensions

AOP Options Menu

AOP Gain Analysis


AOP Azimuth Plot

AOP Elevation Plot


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