The ¼ Wave Droopy Ground Plane 2 Meter Antenna
In the past we’ve talked about the many benefits of Ham Radio, and how every good survival plan should include some type of emergency communications equipment. When the power lines go down and cell phones stop working; the ability to send and receive information is going to be a critical factor in determining the outcome of your situation
In the coming month’s we are going to give some attention to the topic of emergency communication, and show you what it takes to communicate when the grid goes down.
Today, I’m going to show you how you can easily build a homebrew 2 Meter ¼ Wave vertical antenna for under $10. This antenna is perfect for HAMS that need a quick reliable solution for local 2 meter communication. It’s also a great antenna for emergency communication and can be fabricated and launched in a mater of minutes.
The ¼ Wave Droopy Ground Plane Antenna
ANTENNA PARTS LIST:
Keep in mind that this, and most HAM antennas, can be made with parts that you probably already have laying around your home. The parts below are what I used to build the antenna, but you can substitute most of these parts with whatever you have around your house.
- 1- 1 1/2″ PVC Pipe
- 2 – 1 1/2″ Adapter
- 1 -1 1/2″ Cap
- 1 -SO-239 Connector
- 50 ohm Coax
- Galvanized Utility Wire (16-14 Gauge) – Straightened and cut into 5 pieces (lengths below)
- 4 – 6-32 Stainless Machine Screws
- 4 – 6-32 Stainless Machine Hex Nuts
- 4 – #6 Crimp on Ring Tongue Terminals (16-14 Gauge)
Assembling the Antenna
The first thing I did was to assemble the actual working part of the antenna. To do this I cut and straightened 5 pieces of the galvanized utility wire down to about 20 inches.
To figure out the length of your antenna’s vertical and radial elements, you can use the following formula:
Length (in.) = 2808 / F
F= 146 mHz.
I used the middle of the band which is 146mhz. This calculated out to about 19.25”, which is what I eventually cut the wire down to when I had everything assembled.
Attaching the Vertical Element and Radials
Take 4 pieces of wire, which will be used as the antenna’s radials, and attach them to SO239 mounting holes using the machine screws and the ring tongue terminals.
Next, solder the vertical element of antenna to the center connector of the SO239 connector. After you are done soldering and connecting the radials, your connector should look like the picture above.
Final Antenna Assembly:
PVC – The PVC is used to stabilize the antenna so you can attach it to a tree, a tripod stand or anything that gets it up off ground. If you don’t have PVC, you can use any non-conductive material to build the base.
Take the 1 1/2” adapters and glue them to your PVC pipe; one on the top and one on the bottom (the bottom adapter can be used to mount the antenna to a flange for stability). Next drill a 5/8 inch hole in the top of your 1 1/2” cap and then attach it to the top adapter.
Slide the coax through the PVC pipe and connect to your SO-239 connector.
Bend your radials at a 45 degree angle; you now have a working antenna.
For under $10 worth of material, I was able to build a reliable antenna that can easily access all of the local repeaters with only 5 watts of power. At 25 watts, I was able to hit repeaters over 100 miles away.