February 24, 2020
Description
This thing is a collection of parts to build a duo band dipole for 2m / 70cm or a ultra portable duo band yagi-uda antenna. The yagi-uda weighs only about 340 grams and can be transported easily in a backpack as the elements can be nested inside the boom.
The files contain the upper and lower side of the element mounting brackets that can be clamped onto a 16mm PVC electrical installations pipe. The radiators can be made of 2,4mm aluminium welding rods for TIG welding.
The coax cable is connected by sticking the ends of the conductors into the side holes before tightening down the screws of the radiating elements clamp. The nuts inside the brackets double as connectors
You will need:
About 5m RG58 coax cable
6 M5x30 cylinder head screws
6 5,3/15mm washers
2 5,3/10mm washers
6 M5 hex nuts
6 M5 wing nuts
1 16mm dia PVC electrical pipe (~60cm long)
1 piece of PP-cord for attaching the cap to the boom
1 Coax plug of your choice (PL / N / BNC /...)
As you see in the pictures, i wound 9 turns of coax around the boom after pulling it through a hole and the length of the boom the rear end, to act as a choke coil.
The radiating elements lengths are as follows (I bent them around a 5mm screw before cutting them to length. You may need to adjust them for minimum VSWR at your desired frequency range, so leave a bit longer at first)
for 70cm: 149mm per side
for 2m: 486mm per side
The reflector elements are as follows:
70cm: 356mm (as one piece)
2m: 1028mm (cut in two 514mm pieces for storage inside boom, can be bridged by a 55mm long piece of rod in the free slot of bracket.
The distances of the elements along the boom are as follows:
70cm: 110mm
2m: 414mm
You can easily leave the reflecting elements away and just use one bracket along with the radiating elements to form a highly effective but yet unobtrusive 2m/70cm dipole antenna for your balcony. For I dipole, I do not bend the radiating elements but cut them separately for easy length adjustment inside the bracket.
License:
Creative Commons - Attribution
sebste
