Tuesday, 7 October 2008

New antenna at QTH?

Been agonising over this for ages (2 years+).

Do I need or want a better antenna at the home QTH? Every time seem to operate from home for contest etc it involves putting up a dipole as the vertical (Hustler 6BTV) works FB but just doesn't seem as useful for inter G working on 80m and seems limited to working EU stations only. As soon as a dipole or G5RV goes up the US opens up and there is more DX heard.

The recent windy WX in UK had seen a tree limb came down at the bottom of the garden and it bent literally the vertical over at 60 degrees about 5ft AGL and also took out the dipole support. A new length of Ali tube was obtained and antenna is back up again but thought time to consider the options.

Current thoughts are:

Cobweb
UPDATE HERE:
http://m1kta-qrp.blogspot.com/2008/10/cobweb.html

(http://www.g3tpw.co.uk/ and http://homepage.ntlworld.com/andymuza/G7VOT/Cobweb/Cobweb.html)


Nice small footprint and will fit on gable end of garage or side of house easily!
Downside is long feeder.

Heaxbeam (http://www.leoshoemaker.com/hexbeambyk4kio/general.html)



Gain but bigger footprint. c5m radius
Will fit on side of house but not easily!
Downside is also long feeder.

Simple Dipole for 80m or a fan dipole.



However run into the "wires down the garden XYL and neighbour problems".

Copper Pipe, got some 22mm pipe and 90 degree couplers and end stops or 1/2" heliax (LDF-450) Mag loop.

I have a small vaccum capacitor bought at Friedrichsafen 2007 and a gear box of Mecano Gears and inners from a small hand drill. See this site for one option http://www.qsl.net/hb9mtn/hb9mtn_magnet_80.html

Maybe could build this and put in attic?

Do nothing and stick with vertical and temporary dipoles (maybe end result depending on planning) and add a sloping wire from house to the shack with a tall support at the shack end, would result in about a 50m run which is enough for a 160m 1/4 wave. like this:


The ground system could/would need to be be improved as well so I picked up a few extra ground spikes that were on sale at B&Q.

So bought a couple dozen 5m telescoping fishing poles and will start a 'shoot off' as I will construct the cobweb and hexbeams for all bands 10m through 20m. And a mag loop for 40m and 80m. For 160m I will look at the sloper and any other antenna designs I have seen.

I might end up having to stick with the vertical and a dipole but this might be fun.

As I progress will post the results and which tuners worked best if needed.

My rear garden is larger than most at > 50m long but narrow 15m, It runs N-S with shack at South, house at North. I have 2 large 60ft+ poplar trees next door to the East. No cannot use them I asked but it is tempting to fire a line over them but when windy the tops whip about a lot so any antenna would be shredded or drag the shack with it!
All activity will be QRP only.

1 comment:

Anonymous said...

'Been 2½ tears since your posting of the antenna dilemma, did you have any luck with the Cobbweb design? If so, what's you preference, that or an Hex-beam?

73,
Scott
KC6O