3G/4G antenna tutorial
Last edited 17.3.2015
This is a log periodic 3g antenna for mobile connections. It is simple, very easy and cheap to make. I did it for personal need when commercial antennas (and still today) were expensive and not effective enough.
Dxzone.com has lot of information and most of the information I used is from this site. Therefore any information you find in this tutorial is considered to be licensed under GPL license and any commercial use is forbidden.
First background theory.
L is total width of the "spikes" in side of antenna. R is distance for these "spikes" but if you bought one that is ready made you have make some adjustments.
I bought two Log periodic antennas from local store called Tokmanni, they cost approx. 15 euros each. Using side cutters it's easy to cut these "spikes" to a suitable length . In picture below I used dxzone calculator and calculated this antenna suitable values of 850 - 2100 MHz region. If you want to use this antenna with 4G then just changes values in calculator accordingly (although this antenna covers 1800 Mhz).
Actual cutting to suitable width I did so that I checked from calculator results how I should cut "spikes". Because "spikes" are not in right place I used a ruler as helper and draw the line where "spike" should be cut. Then cut them accordingly as close as possible the calculator results.
For 3g antenna your 3g usb modem have to support external antenna or you can simply make connector yourself like I did :)
Then, the actual antenna I attached them together parrallel (with using non-conductive material!) and then connected antennas in "serial" with using a thick copper wire (from normal MMJ cable).
!IMPORTANT! Remember that antenna must be upright position , not like normal television antenna.
Antenna from side.
Antenna connected in "serial". I used wood as insulator between two antennas.
Antenna connection from "tip" of antenna.
It is not the most beautiful antenna but it sure works great and you'll get "bang for the buck" with this one, since cost is around 30-40 euros.
At first without antenna I was unable to keep even GPRS connection, or even EDGE. With this antenna I'm getting stable 3g, even with bad weather.
Please note that the antenna must be aligned accurately.
The nearest base station is not always the fastest. I'll take connection to base station approx. 10km away , instead of 2km to get bandwith of 5 - 9Mb/s. I hope you can enjoy good surfing with this antenna :)
Here is screenshot from speedtest taken 14.3.2015, nearest base station (within 2km) is now upgraded to support 3g.