GP5 Five Band Vertical Antenna OH7SV

This is my 5 band vertical antenna in my summer cottage. It is for 14MHz, 18MHz, 21MHz, 24MHz and 28MHz.
Each element is electrically 1/4 wave long and they can be easily adjusted with the telescopic construction. The tuning clamps are at 2 meter height.
Click the pictures to enlarge.

GP5 antenna in working position in summer cottage. The tube supports are made of PC plastic, spacing 20cm.

Guy ropes binding in progress. Yrjo OH3YP is helping.

GP5 is very light. See the clamps for each band individulal tuning at 2 meter height.
Tube tops are capped with plastic plugs.

The antenna base is laser cut stainless steel. S
tainless steel nut rivets for radial wires.
The base insulator is machined of POM plastic. Water tight
type N bulkhead connector.

Common mode balun in the feeding point. Four radials for 20m and two for each higher bands.

Tuning in progess with miniVNA Pro. Tuning was very easy because there is very little mutual effect.

Original GP5 sketch

SWR  graph

Aluminum tubes
Material natural aluminium (not anodized)
Upper tube inside lower tube. Lower tubes cross split abt 7cm for clamping

14MHz (center tube)
Lower tube 32x1.5mm L=2.1m, upper tube 28x1.5mm L=3.3m

Higher 4 bands
Lower tubes 12x1.5mm L=2.2m, folded 45 degrees at 28cm
Upper tubes 8x1mm
18MHz L=2.1m
21MHz L=1.6m
24MHz L=1.0m
28MHz L=0.7m

Antenna base drawings
Base drawing 1
Base drawing 2
Base insulator

Update 2017-01-29 OH7SV

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