Here is a preview of an antenna I've mostly completed building. Simply put, it's a 2el 2m beam designed such that it's easily transportable on a plane for when I travel. I wanted an antenna for 2m SSB work that I could easily place in my suitcase along side my trusty FT-817ND and some battery power. Further, this would also suit back-packing/hiking/SOTA.
I will provide more photos, but I'm currently experiencing some issues with my primary computer – which also looks after all my photography – so for now one lonely iPhone photo.
Anyway, basically it's a frame made of PVC sections that can be broken down into sections all ~50cm long. Although in the photo you see some orange conduit, that was only for testing and tuning. But the section that fits into the PVC in the photo, is actually made up of two inter connecting 50cm sections to provide a 1m handle that the user can hold in one hand with the mic in the other.
Onto the frame, one simply uses electrical tape to attach the wire elements. The DE is a simple half wave dipole soldered to coax. It has three ferrite sleeves near the join to act as a balun/choke. Further, for strength there is a small piece of ply wood to which each of the three sections (coax, and each leg of the dipole) are cable tied to. The reflector is then one piece of wire (94cm) with a small cable tie right in the middle to mark the centre for alignment when attaching to the frame.
The frame is also such that it allows for easy variation of the polarisation. In the photo it is obviously vertical, but when I was first testing it was horizontal. However just as I finished testing, VK1SV and VK1DSH were heard on FM so after making initial contact I quickly rotated it so that it was vertical. As one would expect, instant improvement of signals was found.
However (when I finish) each T Piece will be permanently glued to at least one section of PVC (with PVC glue) to increase rigidity and strength – more on this when I finish it and take photos.
After tuning the DE (SWR adjustment) I was then able to also do some basic tests with my current Field Strength Meter (FSM). These tests confirmed the beam definitely has F/B characteristics. These tests where then further validated with receive tests while I was talking with VK1SV. He was some ~20km away only on 5W and thereby only coming through at about S5. As a result, I could almost completely block his signal if I turned the beam away from him resulting in about S1. VK1DSH on the other hand was coming through at full scale, however turning the beam also dropped his signal by about 2 S points.
With my new FSM – parts arrived today – I look forward to measuring if there is any gain achieved from having the reflector. I plan to do this simply (thanks to using PVC) by adding and removing the reflector between tests.
Anyway, there you have it. My simple beam that I can take on plane travel with me. Thanks to Andrew (VK1DA) for providing the inspiration. I actually asked if he had any suggestions for such an antenna, and this is where he pointed me. Thanks!!
I'll provide more information for building when I get a chance – probably a couple of weeks away. 😉
P.S. It seems to have a rather large bandwidth – covering the whole 2M band under and SWR of 1.5:1 – thereby allowing it to be used for both SSB and FM.