Some points about 2.4Ghz coaxial cable antenna for routers and Robotics Vehicles: Radio equipment using the license-free 2.4-GHz ISM (industrial/scientific/ edical) band is also rife among robotics fans, just think of what you can do with Bluetooth, wireless cameras, remote control, or even a WLAN client or access point fitted on a robot vehicle!
Point is, such homebrew applications typically require an antenna that’s (1) omnidirectional, (2) ‘sort of’ flexible in view of the damage and bashing it may have to take and (3) low2 cost. The antenna shown here fulfills all three requirements brilliantly. See for yourself, the pictures say more than 1 kwords.
You will need:
• a short piece of 50-Ω coax cable like RG58(C)U with a crimpedon BNC plug (‘borrow’ a cable from the IT dept.);
• a sharp (hobby) knife;
• a pointed tool like a strong needle or a watchmaker’s screwdriver;
• a ruler;
• a soldering iron (optional);
• a hot glue gun;
• common sense and about 30 minutes of your time.
The raw material: a short piece of 50-Ω coax cable.
Cut off about 40 mm of the outer insulation. This will expose the braid that forms the cable shield.
Push down the braid to expose the inner insulation.
Using the pointed tool, carefully unweave the braid strands.
Until your hairdressing looks something like this…
Distribute the strands into four equally sized and likewise spaced bundles
Now bend them into a 45-degree angle with respect to the cable. This angle will result in an antenna impedance of about 50 Ω.
Cover the bundles with solder. Although this step is optional, it does enable the ground plane elements to hold their shape better, and prevents untwisting of the strands.
Apply a few drops of hot glue…
… will help keep the proper shape.
Cut the radials and the radiator to a length of 30 mm (yes that’s 0.25 lambda).
And we are done! This is the 2.4GHz groundplane antenna.
Remember that you have to use a proper connector as the device you are connecting the antenna.