Magnetic Loop Antenna Selfmade Tubby outdoor HB9ISP

Info: Homebrew rectangular loop made of thick copper tubing with vacuum capacitors, 10 m to 160 m.
Conductor: Copper tube 100mm
Capacitor: Vacuum Capacitor
Environment: Suspended 5 m above ground next to the house.

Antenna Efficiency Overview

Band 80m 60m 40m 30m 20m 15m 12m 10m
Frequency f MHz 3.573 5.357 7.074 10.136 14.074 21.074 24.915 28.074
Intrinsic bandwidth Bint kHz 2.4 5.5 6.7 9.3 12.1 66.0 201.0 350.0
Source of Bint SWR = 2.62
Loop diameter D m 1.006
Conductor diameter d m 0.100
Loop count n 1 1
Inductance L H 1.51e-06
Capacitance C pF 1314 585 335 163 84.7 37.8 27 21.3
Unloaded Q0 1 1489 974 1056 1090 1163 319 124 80
Damping resistance RT Ohm 0.0228 0.0522 0.0636 0.0882 0.115 0.626 1.907 3.321
Radiation resistance RR Ohm 0.000398 0.00201 0.00613 0.0259 0.0968 0.493 0.973 1.583
Loss resistance RLoss Ohm 0.0224 0.0502 0.0574 0.0623 0.0180 0.133 0.934 1.738
Power to antenna Pfwd W 100 100 100 100 100 100 100 100
swr_min 1 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
etaSWR_ant % 100 100 100 100 100 100 100 100
Power antenna load Pload W 100 100 100 100 100 100 100 100
Antenna efficiency η % 1.75 3.86 9.64 29.4 84.3 78.8 51.0 47.7
Loop current I rms A 66.27 43.78 39.66 33.66 29.51 12.64 7.24 5.49
Loop voltage Uloop rms V 2247 2225 2662 3238 3941 2527 1712 1462
Magnetic dipole moment m A m² 52.705 34.816 31.544 26.774 23.473 10.050 5.759 4.364
Link to calculator calculator calculator calculator calculator calculator calculator calculator calculator

Environment

Outdoor antenna setup.

A wooden ladder was secured to the house with ropes. At the top of the ladder, a pulley redirects the rope used to raise the antenna. At maximum elevation, the antenna is 5 m above ground and maintains at least 5 m distance from other metallic objects. The ladder itself only has small metal parts and screws.

House cross-section near the outdoor antenna location.

A detailed description is available here: https://arxiv.org/abs/2607.10828


Overview of all Antennas with filter/selection: compare page
Overview of all Antennas static: static compare page
2026 Peter Märki (HB9ISP). This project is created in my free time and has no commercial background. Provided without warranty of any kind. Feedback is welcome.