Magnetic Loop for 40m, 30m & 20m

Contents Section 1 | Introduction Summary Main Parts Specifications Section 2 | Construction Aluminium Preparation Frame Construction Loop Wrap Coupling Loop Capacitor Motor Control Control Box Section 3 | SWR and BW 40m Band 20m Band Section 4 | On Air Experience First Contact Contact with Portable Station

Section 1 Introduction

Summary

My QTH is close to the city of Melbourne Australia. I live on a small block of land with antenna height restrictions which is impractical for erecting traditional antennas for the 20m band and above. This restriction led me to investigate small antennas with the magnetic loop looking the most interesting one to pursue.
The below antenna is based on the K8NDS design magnetic loops. The main structure is made from pressure PVC for the mast and pool noodles for the loop. Copper strap for the loop element is difficult to source in Australia and the few sources are expensive. Aluminium flashing from a local hardware store was chosen as a second option as it is cheap and the ideal thickness.

Main Parts

• Aluminium Flashing. 10m x 150mm x 0.3mm
• Russian VVC. 5-250pF, 5kV
• 12V Geared Motor & Bracket. 30 RPM, Torque 4kg.cm
• Motor and Capacitor Flex Shaft Couplers
• 3 Pool Noodles 1.5m x 70mm
• PVC Pipe 1m x 20mm
• PVC Pipe 3m x 50mm
• PVC Pipe 200mm x 70mm
• Plastic Cutting Board

Specifications

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