What is a Linear Loaded Dipole?

I had posted about Loaded Coil Dipole Antenna earlier, which is a means of electrically shortening the physical length of a dipole antenna for those with space constraints, using a loading coil. It is useful for single band operation with narrow bandwidth. Of course it is a trade off between performance and fitting a dipole into a shorter available space. I just came up on the concept of Linear Loaded Dipole antenna on Twitter or X. It is actually a fancy way of saying “fold back on itself” according to M0PZT. Overall length is reduced without adding a loading coil and performance is still good for those with ony a small garden like me to mount conventional dipole antenna. It can be used in horizontal, inverted V or sloper patterns. M0PZT has a 40m antenna which has an overall length of 12m only, which is only a bit longer than a 20m antenna and sounds nice! More interesting for me is the suggested 80m antenna at 27.8m length, which I may try when the Solar Cycle 25 starts coming down and higher bands go down. But I will need zig-zag mounting for 27.8m length as I am just able to squeeze in my 20m long inverted V 40m antenna here.

The antenna elements could be built using a ladder-line or with PVC pipe pieces as separators between the folded components. A 1:1 current balun is used at the feedpoint and a standard 50 Ohms coax takes the signals to and from the radio. M0PZT has used 20mm PVC pipes as spreaders to keep distance between the folded components at 50mm. Folded parts of the wire should be parallel to each other, requiring at least 1.6mm thick wires. Like the loaded coil dipole, linear loaded dipole also has a narrow bandwidth and might need a tuner to ‘touch up’ the VSWR at the radio end. Still it is said to be a good compromise antenna when you do not have the space to install a full size dipole antenna.

Still more interesting is the linear loaded dipole antenna used by 9V1KG which has three folded layers, just as we have two fold and three fold umbrellas! Wonder anyone has higher number of folds as well? We have even five fold umbrellas here, to fit into a small handbag. As the feedpoint impedance was 10 Ohms, 9V1KG used a quarter wave transmission line transformer with two parallely connected 50 Ohms coaxial cables to match to the 50 Ohms impedance of the radio. One of the readers suggested 1:4 balun instead of the transmission line transformer. 9V1KG could work DX from around the world on 15m CW using his linear loaded dipole antenna. That is yet another interesting option for hams like me with space constraints, who are not very small in number among the city dwellers globally!