On Sunday, November 1, 2015 at 1:41:26 AM UTC-7, Martin Gregorie wrote:
On Sat, 31 Oct 2015 17:20:18 -0700, bensoaring wrote:

On Saturday, October 31, 2015 at 6:56:02 PM UTC-4, Martin Gregorie
wrote:
On Sat, 31 Oct 2015 15:28:07 -0700, bensoaring wrote:

On Saturday, October 31, 2015 at 4:21:12 PM UTC-4,
wrote:
Well, this is an old discussion.
I already published my home built bottom fed Flarm (and ADSB) dipole
antennas 2 years ago.
https://sites.google.com/site/threeu...rm/powerflarm-
antennas
By now, my antennas are painted black.

Thanks 3U for contributing. Yes I'm familiar with your work and
website. I wish you would expand your article to include "how to"
details so DIY guys like me could fabricate their own antennas.

Regarding PowerFLARM antenna A, what amount of signal degradation
would be experienced if there were two "A" antennas by means of some
sort of splitter?

A thought: you can pick up nylon-covered steel trace (1.3mm OD, the
steel trace is 1.0mm diameter from eBay (10m for $8.95) and good
fishing shops also stock it. Crimp the end over and add a blob of epoxy
for eye protection and there's a very thin antenna. On a glare shield
one of these would be almost invisible. The older Swiss FLARMs, used
antennae which were just a 1/4 wave length of what looked like 0.8mm
(1/32") music wire mounted at the centre of a circular 80mm diameter
metal ground plane.

The fox-hunting crowd, i.e. orienteers who run XC in search of a hidden
radio beacon) make Yagi DF antennae from steel tape-measures and
plastic plumbing pipe which seem to work pretty well, so would this
nylon-coated steel trace be any good for making up PowerFLARM dipoles
or bottom-fed antennae?

I'd be interested to hear what somebody who understands antennae thinks
about using this stuff or even thinner trace material: it is available
down to 20 lb breaking strain.


--
martin@ | Martin Gregorie gregorie. | Essex, UK org |

Smiling...us redneck bass fisherman know this as nylon coated stainless
steel fishing leader.

I don't fish (well, once or twice trolling for trout on Lake Taupo) and
have only used this steel trace (the UK term) for connecting controls to
the timer in free flight model aircraft.

Would you use it for a FLARM antenna? I suppose you'd have to crimp the
feeder connection as its unlikely to take solder.

BTW, here's a link to one of those Yagis. In case you're wondering, the
reason they like 'em is partly because they're light and partly because
you can crash through the undergrowth with one without breaking or
bending it:

http://theleggios.net/wb2hol/projects/rdf/tape_bm.htm


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Yagi antenna are great for highly directional transmit/receive. I.E. if you placed a yagi/flarm antenna pointing forward, the signal in any other direction would be practically non-existant. Not a good choice for a signal you want to send/receive in all directions.

Mike