Since I have text and pics on these scattered about in threads where they don't belong, I decided to compile them here. The idea for both came from this article: A Stealthy Homebrew Vertical Dipole Antenna Using Strong Tie "T"'s My thanks to both John and Scott.
Let's start with the GP:
Homemade Ground Plane Using 4' Firestiks
Materials:
A. One Simpson Strong Tie (6" x 12"). These are available at any Lowe's or Home Depot.
B. Two hose clamps (For attaching antenna bracket to mast)
C. Three 4' Firestik mobile antennas (I used Firestik II's with tunable tips)
D. One PL259 stud mount (I used a Firestik KV-4A)
E. Two lug stud mounts (I used a Firestik KV-4)
F. One PL259 right angle coax connector (male to female).
Instructions:
1. Drill a ½” hole in the center of the 12” length of the strong tie.
2. Make a 90 degree bend so that the 6” length is pointed down (this is what attaches to the mast.)
3. Using a vice, make two bends in the 12” length 3 ½” from each end, leaving 5” across the top. Bend each downward and inward so that the two form a 90 degree angle. This will insure that the radials will be pointing outward at 45 degrees insuring an impendence of about 50 ohms.
4. Install the PL259 stud mount in the top center hole. This will hold your vertical element. Be sure and use a plastic sleeve with the top portion so the antenna does not contact the metal bracket. Do not use a sleeve between the coaxial connector and the bracket. This will insure the coax’s shield is grounded to the bracket.
5. Attach the Right Angle Coax Connector.
6. Holes for the radials come pre-drilled on the strong tie. Simply install lug studs in them. Be sure and use only one plastic sleeve (or none) on each so the antennas will be in direct contact with the metal bracket.
7. I chose to add a self-tapping screw in one of the small pre-drilled holes to attach a ground wire to which will run to a ground rod.
All that's left is to screw in the antennas!
Antennas with only one radial are largely directional (stronger in the direction the radial is pointed.) And while 3 or 4 (or more) radials are recommended for a fully Omni-directional antenna, some say 2 radials are nearly as effective and produce more of an Omni-directional pattern than the 180 degree pattern that might be expected. This is what I've found.
How good does it work? About what you'd expect. Mine sits atop a 15' mast and I'd say its performance is equal to (or a little better than) installing a 4' Firestik in the center of your car's roof, and then hoisting the vehicle 15' in the air.
Now, if you don't have much in the way of locals to talk to (as I don't) then a horizontal dipole might be what you want.
Homemade Dipole Using 4' Firestiks
Simple to make. Just one piece of angle iron, a "U" bolt with nuts and washers, two 4' Firestiks with stud mounts, and a 90 degree adapter.
Tuning both this and the ground plane antenna was a snap using the Firestiks' II tunable tips.
Initial readings on the dipole:
CH 1 - 2.0
CH 20 - 1.8
CH 40- 2.2
Final readings with each tip extended 1/2":
CH 1 - 1.3
CH 20 - 1.1
CH 40 - 1.2
I don't use a balun. By running my coax straight down the length of the mast, it is perpendicular to the antenna for more than the suggested 1/4 wave (8.5'), thus providing proper impendance and preventing "RF in the Shack". At least I guess it does. My SWR is great and if I have "RF in the Shack" (as I've so often read about) I don't know it.
Note: I recently revised my dipole bracket by switching to a 6"x6" strong tie, 1.5" wide. I then cut 2" off one end making it 4"x6", and added 2 small "L" brackets in the angle to make it stiffer than the previous bracket. It is also lighter.
Summary:
If you are looking for something your wife and neighbors won't complain about but still works really well, either of these will fit the bill, depending on your needs. No way are they going to replace a full-sized base station antenna, but if you know what to expect going in, I think you'll be happy with them. I am. Another nice thing--they hardly move in a gale. And the 4' Firestiks are rated 900 watts.
Also, I chose to use 4' Firestiks, but any brand (Everhardts, Wilsons, Francis, etc., and any length (the longer the better) will work.
Let's start with the GP:
Homemade Ground Plane Using 4' Firestiks
Materials:
A. One Simpson Strong Tie (6" x 12"). These are available at any Lowe's or Home Depot.
B. Two hose clamps (For attaching antenna bracket to mast)
C. Three 4' Firestik mobile antennas (I used Firestik II's with tunable tips)
D. One PL259 stud mount (I used a Firestik KV-4A)
E. Two lug stud mounts (I used a Firestik KV-4)
F. One PL259 right angle coax connector (male to female).
Instructions:
1. Drill a ½” hole in the center of the 12” length of the strong tie.
2. Make a 90 degree bend so that the 6” length is pointed down (this is what attaches to the mast.)
3. Using a vice, make two bends in the 12” length 3 ½” from each end, leaving 5” across the top. Bend each downward and inward so that the two form a 90 degree angle. This will insure that the radials will be pointing outward at 45 degrees insuring an impendence of about 50 ohms.
4. Install the PL259 stud mount in the top center hole. This will hold your vertical element. Be sure and use a plastic sleeve with the top portion so the antenna does not contact the metal bracket. Do not use a sleeve between the coaxial connector and the bracket. This will insure the coax’s shield is grounded to the bracket.
5. Attach the Right Angle Coax Connector.
6. Holes for the radials come pre-drilled on the strong tie. Simply install lug studs in them. Be sure and use only one plastic sleeve (or none) on each so the antennas will be in direct contact with the metal bracket.
7. I chose to add a self-tapping screw in one of the small pre-drilled holes to attach a ground wire to which will run to a ground rod.
All that's left is to screw in the antennas!
Antennas with only one radial are largely directional (stronger in the direction the radial is pointed.) And while 3 or 4 (or more) radials are recommended for a fully Omni-directional antenna, some say 2 radials are nearly as effective and produce more of an Omni-directional pattern than the 180 degree pattern that might be expected. This is what I've found.
How good does it work? About what you'd expect. Mine sits atop a 15' mast and I'd say its performance is equal to (or a little better than) installing a 4' Firestik in the center of your car's roof, and then hoisting the vehicle 15' in the air.
Now, if you don't have much in the way of locals to talk to (as I don't) then a horizontal dipole might be what you want.
Homemade Dipole Using 4' Firestiks
Simple to make. Just one piece of angle iron, a "U" bolt with nuts and washers, two 4' Firestiks with stud mounts, and a 90 degree adapter.
Tuning both this and the ground plane antenna was a snap using the Firestiks' II tunable tips.
Initial readings on the dipole:
CH 1 - 2.0
CH 20 - 1.8
CH 40- 2.2
Final readings with each tip extended 1/2":
CH 1 - 1.3
CH 20 - 1.1
CH 40 - 1.2
I don't use a balun. By running my coax straight down the length of the mast, it is perpendicular to the antenna for more than the suggested 1/4 wave (8.5'), thus providing proper impendance and preventing "RF in the Shack". At least I guess it does. My SWR is great and if I have "RF in the Shack" (as I've so often read about) I don't know it.
Note: I recently revised my dipole bracket by switching to a 6"x6" strong tie, 1.5" wide. I then cut 2" off one end making it 4"x6", and added 2 small "L" brackets in the angle to make it stiffer than the previous bracket. It is also lighter.
Summary:
If you are looking for something your wife and neighbors won't complain about but still works really well, either of these will fit the bill, depending on your needs. No way are they going to replace a full-sized base station antenna, but if you know what to expect going in, I think you'll be happy with them. I am. Another nice thing--they hardly move in a gale. And the 4' Firestiks are rated 900 watts.
Also, I chose to use 4' Firestiks, but any brand (Everhardts, Wilsons, Francis, etc., and any length (the longer the better) will work.
