HF Antenna from 1st November 2009 to 8th December 2009:
- 1st floor shack (a small room at the back of my end-terrace house)
- Doublet antenna cut for 20m band mounted approximately 5m above ground:
- One end quite near the shack, the mounting point being on a GRP mast at the back of the house.
- The other end at the bottom of the garden, with a scaffolding pole bolted using two mast clamps to an existing clothes line pole, and extending its height up to about 5m.
- Each end of the dipole has pulleys to enable the whole antenna to be lowered to the ground.
- Twin feeder from the center of the doublet brought to the wall just outside the upstairs shack, and connected outside to RG-58 coax. The end of the coax that connects to the twin feeder is formed into a loop to make a coaxial balun. The other end of RG-58 leads through a hole cut through the cavity wall and into the shack.
- No ATU suitable for twin feeder as yet.
HF Antenna from 8th December 2009 to present:
My current antenna is a development of that above, with a new GRP mast at the front of the house.
This is unlikely to have different performance to the first antenna (it is just the existing arrangement with the dipole moved slightly nearer to the house), but now gives me the flexibility to extend the length for a 7MHz (40m) dipole in future (see below).
HF Antenna Next Steps...
In order to improve my HF antenna I plan to double its length so that I can use it more successfully on the 40m band. This will involve extending the height of the GRP mast at the back of the house, and taking advantage of the mast that I installed at the front of the house on 8th December 2009. The feed point to the improved antenna will be more directly above the shack, and the centre of the dipole will be higher which should give improved reception and transmission. Further developments might include some traps to create a multi-band dipole. I may use higher impedance ladder line, but I would like to be able to test how successful this is, so there may be some test equipment to buy or build first. It may also be possible to extend the total length of the dipole by attaching some wire at right angles (either vertically or horizontally) at the ends of the existing arrangement. I am mindful that I will need to keep an eye on the balance of this antenna, especially as one end is now nearer to buildings etc. The proximity to the house may also increase the chance of interference.
