Thursday, September 19, 2019

Stylish inverted V multiband antenna

Spending most of my radio time /P, I have over the years built and used many different antennas. The inverted V dipole was always one of them but mainly for 40 and 80m as I used end fed verticals for the higher bands (due to the length you quickly end up with an inverted V configuration on lower bands).

I started out with four individual dipoles - one for each band 160, 80, 60 and 40. During my activities I mainly use 80 and 40 of the four so I decided to combine them into one dipole for 40m and 80m - using bullet connectors to change bands. The benefit being that you don't have to change antennas - only lower the mast somewhat to reach the connectors.

Bullet connectors to switch bands

Lately I have been using the inverted V for 20m as well - adding that to the multiband version - as I have found it works well within EU and for DX and again it saves me changing antennas. 

Looking at the radiation diagrams on 20m you can see that the inverted V (blue) radiates better on the higher angles compared to a half wave vertical (red). Note that this is a broad side view. From the ends the inverted V loses significantly more versus the vertical (10dB at a 15 degrees take-off angle on 20m) - so for DX the orientation counts.

EFHW vs Inverted V - 14Mhz - 18m pole

Planning for a future trip where I would have to travel relatively light, I decided to tweak the dipole even further adding all HF bands from 6m down to 80m (160m I would hardly use and would make the antenna rather bulky). 
It took two field tests to get it right. I started cannibalizing the existing 20-80m version. After a few hours out in the field I had cut all elements and established that I needed to change the existing 30m and 40m elements. Then time ran out.
In the second run I found a few peculiar mistakes with 15m being quite a bit off (measuring error the first time?). So a few more cuts and tweaks were needed but 2 hours later my antenna was ready.

One thing to keep in mind is that the impedance of an inverted V changes when the angle between the two legs changes - which it always will between deployments. If you increase the angle, the frequency at which the impendance dips goes down. There is a "sweet spot" of element length vs angle that gives you a dip around 50 Ohm. 

One eye catching feature of my antenna is the way I have attached the elements (for when they are not connected). I started out with simple rope to hold the pieces together but as I unroll the antenna in a different way (rolling it off a cylinder) than I roll it up (adding turns by hand), the elements are twisted each time. The copper wire can cope with that but the connecting rope transforms into a small knot after a while.
So I had the idea to enable the various pieces of wire to twist independently and - having two daughters in the house - came up with a design featuring pink and purple beads. 

I am quite sure this makes it a unique dipole as far as dipole go.

I tested it out during a 3 hour activity from nature reserve PAFF-0067 on 17, 20 and 40m. I worked more than 200 chasers with great reports so it seems to work well.


  1. The antenna looks dinky and fun with these beads. Be ready for attacks of ravens and magpies. :D

    1. спасиба Vitaly. I will have to prepare an even better story now for all the curious passers-by...
      Thanks for pointing out the diagram error.

    2. Now that's right, Lars! Thank you for describing your experiences. I am following your blog with interest.