Two Band Fan Dipole Works on Four Bands 40-15-10-6!

I had a 10/6m fan dipole with a GI pipe as mast. As early rains with lightning had occurred in some places in my region, I thought of removing the GI mast and placing a fibre glass telescopic pole. Meanwhile I wanted to reduce the clutter in the yard and pulled down my end fed half wave dipole antenna so that the fibre glass telescopic mast which was being used for it became free. I used it instead of the GI pipe on my first floor terrace as the mast for a new fan dipole. As I am yet to hear any station on 6 m FM, I removed the 6m elements and added 40m elements so that it became a 40/10m fan dipole. It is well known that half wave dipole antennas will resonate on odd multiples while they are not suitable for even multiples of fundamental frequency.

In that way the 40m half wave dipole resonates on 15m as third harmonic or 3/2 lambda antenna. What about 6m? My friend told me that it can resonate on 6m as well. After all 6m is nearly the seventh harmonic of 40m. I found that the VSWR on 6m was in the tunable range for the built-in antenna tuner of my radio. 20m and WARC bands would show HI-SWR indication in the radio, meaning that it is beyond the tunable range of the built-in antenna tuner of the radio. Today morning I was lucky to work two stations, one from Spain and another from Belgium, on 40m SSB with this fan dipole antenna. Of course band condition also would have been excellent, at about 7 am in the morning, suitable for greyline propagation from this region.

Currently I have used two CPVC pipes of one inch diameter as side supports for the 10m elements. Pulley like mechanism using nylon ropes have been used to bring the antenna down when needed for tuning. Both 10m and 40m elements are in roughly in inverted V patterns, though asymmetric. Ideally, 40m and 10m elements have to be at right angles to each other. But due to limitations in the yard and terrace, the elements are not strictly at right angles to each other nor symmetrically arranged in three dimensions. That is probably why minimum VSWR achievable on the bands 40,15,10 and 6m is near 2. There is mostly likely interaction between elements and surrounding structures like the building nearby as well as plenty of the wires like cable TV, cable internet and power lines around.