|
|
|
|
hints for quasi-professional cage antenna anyone?
SpamLover,
http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm
http://www2.arrl.org/news/stories/2001/05/03/2/
http://www.pust-norden.de/oloog/oloog-2_gr.jpg
http://www.qsl.net/wa2tvs/antennas/archive17.htm
http://www.antenna.be/tel-ave0640.html
iane ~ RHF
..
..
= = = (SpamLover)
= = = wrote in message om...
Goal:
* Minimum fuss 3-30MHz operation, mostly on 5-15MHz.
* Will use step-dowm RF transformer between antenna and low impedance
coax
* May use autotuner on TX
* Like the wirecage antennas still today seen on many a military
vessel.
Available on roof:
- 25ft steel structure (like piramid base for power line)
- about 100 feet space in one direction
-...to abandoned flue chimney, 100ft away and 10 feet lower than base
of steel structure
- roof covered with alu plates on tar (could be all arc welded
together, perhaps.
THIS LOOKS PRETTY MUCH LIKE A SHIP TO ME cept its' 120ft aboveground.
I want to build a wire cage monopole
- sloping down from steel tower
- using tower as counterpoise
- feedpoint at top of sloper, via stepdown rf transfomrer, grounded to
tower
- coax cable lead, with rf choke coils and surge suppressors.
Questions:
- what kind of cage antenna?
- how many wires?
- what spreaders, how large?
- ideal wire?
Current plan config:
- length 14 m = 2 x 4m straight sections, + 2 x 3m truncated cubes
- spreaders at 3-7-11 m
- 140 cm dia. spreaders, each made with two waterproofed bamboo
triangles in "star of David" configuration; wire kept parallel at 70cm
distance from each orther.
- material: .8mm copperclad, abt. 90 m (270 ft) total.
Any hints, like more/fewer parallel wires, broader / smaller
spreaders, different materials, dirrerent antenna wire, RF
downtransformer, whatever?
Filippo
|