WIFI antenna

WIFI, wi-fi, microwave, Wireless Internet is synonymous with data transmission (the Internet) ether at relatively high frequencies. The advantage is mainly mobility in combination with high transmission speed (Internet access speed is usually limited by the provider).

The networks of the most widely used standards 802.11b and 802.11g work at the frequency 2,45 GHz. This is not far from the radio amateur band 13 cm and so all laws apply as for this microwave band.

The biggest problem with WIFI is signal propagation in space. Unless we are satisfied with a range of up to a few meters (tens of meters), it is necessary to consider a more powerful antenna. Commercially, directional yagi antennas and satellite dishes are mainly used on the client side. However, their price is relatively high.

I compared three antennas - the original one supplied with the AP, homemade DL7KM (figure eight) and a 10-element loop quad, which has proven itself excellently. The best DX, which I did for this antenna is the AP in the distance 4,5 km.

The design of the antenna is simple (simpler than it looks), requires normal mechanical tools and more solder (more than 100W).
The inspiration for this antenna is the material on http://www.paramowifix.net/antenas/loop_uda_yagi/. It is a G6KSN design converted to a frequency as needed. The version described here is quite long.

Thanks to the LoopYagi Design program from G6KSN, we can calculate the antenna for any frequency with any boom length. In my case, it's the 10-element version. The number of elements was determined by the length of the copper support tube - the boom. The entire antenna is no longer than thirty centimeters.

Here are the dimensions calculated by the program:

The reflector is made of cuprextite. If we do not have a compass available, we can measure approximately the size according to CD, hi. With a large soldering iron, we properly attach the supporting boom. It is a copper tube approx. 30 cm in diameter 10 – 12 mm. We also drill a hole for the N-connector.

On the boom-e, we mark the positions of the individual elements with a file. We prefer to make the grooves longer, so that they can be easily seen while flying.

For the elements we will use Cu conductor with a diameter 1,5 mm. We will make the ring like this: we cut the exact length of the wire for the element from the wire (e.g.. 135 mm) and bend it on a pipe of a suitable diameter. After being released from the pliers, the wire springs back, therefore, it is preferable to use a tube with a smaller diameter than the element. This is how we prepare all the elements, also the emitter.

It is then enough to solder the elements onto the boom with a large soldering iron. After soldering all the elements, we cut the radiator exactly opposite the boom (we can too 1 mm). We mount the N-connector. From a thin coaxial cable (RG-58 can also be used if it is not better) we will make a jumper. We shorten all outlets to a minimum. We love Káblik.

The mechanical construction is obvious from the photos:

 

You can download the Loop Yagi CALC program .: YOUR :.. The antenna was tested with excellent results only on WIFI, not yet at the AMAs. With WIFI, the effect of polarization is noticeable (vertically, horizontally, “and something in between”) and directionality. Tuning to the best signal requires a little patience.

For outdoor use, do not forget to fix it well against moisture.