For Wire Verticals on Fiberglass Poles
CAUTION: DO NOT DRILL HOLES IN THIN-WALL TELESCOPING FIBERGLASS POLES - NO EXCEPTIONS!
Drilling a hole in the wall of the tubing damages the structural strength of the material and often causes breakage. K9YC learned that lesson the hard way, dispite all of his vast antenna experience. If you do it anyway and break the pole, look in the mirror for the blame. Please don't blame it on the manufacturer like K9YC did. If you are unsure of how to use your pole, ask the manufacturer. For information on how to extend fiberglass poles, see: <<extensions>>
- Wire Size (1a. Vertical Radiator) / (1b. Top-Hat Wires)
- Effects of the Pole on the Velocity Factor of the Radiator Wire
- BEWARE of Carbon-Fiber Poles!
- Feeding Vertical Antennas
1a. WIRE SIZE (Vertical Radiator):
The power rating of CQ-532 (sold by Spiderbeam or THE WIREMAN) depends on the frequency of use. This is due to skin effect. On low frequencies, skin effect is not so predominant. The RF current penetrates deeper into the wire and flows through the steel... which adds loss. On higher bands it will flow more on the outside of the wire which is copper.
- For up to 600w on 160m, use 1mm diameter wire. Recommended: CQ-532 Copperweld (AWG-18)
- For up to 1KW on 160m, use 1mm (AWG-18) for the top half of the radiator wire and 1.5mm (AWG-14) for the lower half of the radiator wire. Or use 2 strands of CQ-532 on the lower half of the vertical radiator.
- For up to 1.5KW on 160m, use 1mm (AWG-18) for the top 1/3 of the radiator wire, 1.5mm (AWG-14) for the middle 1/3 and 2mm (AWG-12) for the lower 1/3 of the radiator wire. Or, a combination of 1/2/3 strands of CQ-532 is also OK.
- For all other bands, CQ-532 is OK for up to 1.5 kW. If you are really fussy on 80m, use AWG-14 on the lower half (or 2 strands of CQ-532).
CAUTION: DO NOT RUN THICK WIRE TO THE TOP OF TELESCOPING FIBERGLASS POLES
Running too thick of a wire to the top of a telescoping pole
will probably cause the pole to BREAK in a storm.
Never use wire thicker than 1mm (AWG-18) for the top 5 meters (16 ft.) of the pole!
Do not worry about the antenna not being broad-banded due to using copper wire instead of aluminum tubing. These full-size wire verticals are MUCH more broad-banded than any trap or base-loaded vertical on the planet!
BEWARE of Textbook-Turkeys
who have memorized the text books
but never built anything!
They will tell you that you need thicker wire, and you will break your pole.
FOLLOW THE GUIDELINES listed above and your antenna will be efficient and reliable.
1b. WIRE SIZE (Top-Hat Wires):
CAUTION: Top-Hat Wires must be made as lightweight as possible.
- Use CQ-534 (AWG-26) for the Top-Hat wires. This is about 0.5mm diameter.
- Extend the Top-Hat wires with very thin line. Ideal is PFDF Monofil line.
- Use very lightweight INSULATORS.
2. EFFECT OF THE POLE ON VELOCITY FACTOR OF THE WIRE
We are all familiar with how adding insulation to a bare copper wire decreases the velocity factor, resulting in the need to shorten the wire about 1 or 2% (depending on he insulation material).
When running a wire down a pole, especially when spriraling down the pole (which is the correct way to run the wire), the velocity facto decreases by another 1 or 2%. As a result, we have to shorten the wire a little more.
Never-the-less, always cut the wire according to the formula, then trim the excess as necessary, to bring the wire radiator into resonance on the frequency you desire.
3. BEWARE OF CARBON-FIBER POLES
Carbon-Fiber is a special material which is stronger and lighter than pure fiberglass, for a given thickness. UNFORTUNATELY Carbon-Fiber also absorbs RF.
DO NOT RUN A WIRE CLOSLY PARALEL TO A CARBON-FIBER POLE
We have heard, but not confirmed, reports of people doing this and incurring up to 2 to 3 S-Units of attenuation due to RF being absorbed by the pole. Supposedly, when they moved the wire away from the pole, the signal strength increased by 2 to 3 S-Units.
For this reason, we recommend using poles made only of 100% fiberglass;
To be continued . . .