Additions:
Antenna Modelling Result
Additions:
Deletions:
Additions:
There are many ways to deploy a screwdriver antenna on an RV, this one is optimized for NVIS and convenience. The antenna is mounted on a corner of the roof of the RV, angled back at 45 degrees. The counterpoise is a closed loop of #12 wire on the roof of the RV, 25 x 8 feet. The height of the roof is taken to be 10 feet above ground.
This is a large screwdriver. The lower section is about 6 feet long and two inches in diameter and the whip is about 12 feet long and 1/4" in diameter.
Note that the choice of counterpoise in this calculation is just a wire loop. Using the frame of the RV could improve the situation.
- pattern minimum toward tip of screwdriver, and about -12 dbi at 20 degrees above horizon toward the rear of the RV
This is a very convenient antenna to deploy and tune. The performance is pretty good, especially considering the convenience. It will take a balun (or tuner) to match the source impedance properly. A mount could be set up to lay the Screwdriver on the roof during travel, and permanently mount the counterpose (or use the frame). Then deployment could be a stand-up operation, or even motorized.
Deletions:
There are many ways to deploy a screwdriver antenna on an RV, this one is optimized for NVIS convenience. The antenna is mounted on a corner of the roof of the RV, angled back at 45 degrees. The counterpoise is a closed loop of #12 wire on the roof of the RV, 25 x 8 feet. The height of the roof is taken to be 10 feet above ground.
This is a large screwdriver. The lower section is about 6 feet long, two inches in diameter and the whip is about 12 feet long and 1/4" in diameter.
Note that the choice of counterpoise in this calculation is just a wire loop. Using the frame of the RV could improve the situation. This model seems a bit touchy.
- pattern minimum toward tip of screwdriver, about -12 dbi at 20 degrees above horizon toward the rear of the RV
This is a very convenient antenna. The performance is pretty good, especially considering the convenience. It will take a balun (or tuner) to match the source impedance properly.
Additions:
There are many ways to deploy a screwdriver antenna on an RV, this one is optimized for NVIS convenience. The antenna is mounted on a corner of the roof of the RV, angled back at 45 degrees. The counterpoise is a closed loop of #12 wire on the roof of the RV, 25 x 8 feet. The height of the roof is taken to be 10 feet above ground.
Deletions:
There are many ways to deploy a screwdriver antenna on an RV, this one is optimized for NVIS convenience. The antenna is mounted on a corner of the roof of the RV, angled back at 45 degrees. The counterpose is a closed loop of #12 wire on the roof of the RV, 25 x 8 feet. The height of the roof is taken to be 10 feet above ground.
Additions:
There are many ways to deploy a screwdriver antenna on an RV, this one is optimized for NVIS convenience. The antenna is mounted on a corner of the roof of the RV, angled back at 45 degrees. The counterpose is a closed loop of #12 wire on the roof of the RV, 25 x 8 feet. The height of the roof is taken to be 10 feet above ground.
Deletions:
There are many ways to deploy a screwdriver antenna on an RV, this one is optimized for NVIS convenience. The antenna is mounted on a corner of the roof of the RV, angled back at 45 degrees. The counterpose is a closed loop of #20 wire on the roof of the RV, 25 x 8 feet. The height of the roof is taken to be 10 feet above ground.
Additions:
There are many ways to deploy a screwdriver antenna on an RV, this one is optimized for NVIS convenience. The antenna is mounted on a corner of the roof of the RV, angled back at 45 degrees. The counterpose is a closed loop of #20 wire on the roof of the RV, 25 x 8 feet. The height of the roof is taken to be 10 feet above ground.
This is a large screwdriver. The lower section is about 6 feet long, two inches in diameter and the whip is about 12 feet long and 1/4" in diameter.
Deletions:
There are many ways to deploy a screwdriver antenna on an RV, this one is optimized for NVIS convenience. The antenna is mounted on a corner of the roof of the RV, angled back at 45 degrees. The top whip is about 15 feet long (since this is not used in motion). The counterpose is a loop of wire on the roof of the RV, 25 x 8 feet. The height of the roof is taken to be 10 feet above ground.
Additions:
Note that the choice of counterpoise in this calculation is just a wire loop. Using the frame of the RV could improve the situation. This model seems a bit touchy.
- impedance at feedpoint 9.6 ohms resistive
- 100W 31V 3.2A at feedpoint
- coil 50uH, Q 400, 1120 ohms X, 3 ohms R
- gain -4.5 dbi at 45 degrees
- 37 watts loss in coil, 2dB
This is a very convenient antenna. The performance is pretty good, especially considering the convenience. It will take a balun (or tuner) to match the source impedance properly.
Deletions:
- impedance at feedpoint 12 ohms resistive
- coil 190uH, Q 400, 4280 ohms X, 10 ohms R
- gain -4.2 dbi at 45 degrees
- 65 watts loss in coil, 4.5 dB
This is a very convenient antenna. The performance is pretty good, especially considering the convenience. It will take a balun to match the 12 ohms source impedance properly.
Additions:
- coil 190uH, Q 400, 4280 ohms X, 10 ohms R
Deletions:
- coil xuH, Q 400, 4280 ohms X, 10 ohms R
Additions:
- impedance at feedpoint 12 ohms resistive
Deletions:
- impedance at feedpoint 5.3 ohms resistive
RV Screwdriver Antenna
There are many ways to deploy a screwdriver antenna on an RV, this one is optimized for NVIS convenience. The antenna is mounted on a corner of the roof of the RV, angled back at 45 degrees. The top whip is about 15 feet long (since this is not used in motion). The counterpose is a loop of wire on the roof of the RV, 25 x 8 feet. The height of the roof is taken to be 10 feet above ground.
80 meters
- impedance at feedpoint 5.3 ohms resistive
- coil xuH, Q 400, 4280 ohms X, 10 ohms R
- gain -4.2 dbi at 45 degrees
- NVIS gain -5.5 dbi at 90 degrees
- pattern broad and full toward the groundplane
- pattern minimum toward tip of screwdriver, about -12 dbi at 20 degrees above horizon toward the rear of the RV
- 65 watts loss in coil, 4.5 dB
- Note that this is a really good screwdriver coil, not many are this good
Conclusions
This is a very convenient antenna. The performance is pretty good, especially considering the convenience. It will take a balun to match the 12 ohms source impedance properly.
AlanB, WB6ZQZ
CategoryHamRadio