This antenna has been found about 2 dB better gain than the Freedom antenna, which is specified as 12 dBi antenna. Using 5 metres antenna cable there is no risk of exceeding the output power within the ETSI standard. It can also be built without the Ring to decrease antenna gain if needed especially with very short antenna cable.
The Reflector (aluminum pan) dia = L x 2, the height of the sides = L/4.
In the center of the bottom there is the N connector to left and the dipole to right. A distance from bottom to the dipole is little more than L/4. The Dipole is mounted with an air-insulated coaxial type foot, whose impedance is 50 ohm and length L/4. Inner wire of the coaxial is made of 4 to 4.5 mm rod or conduit and shield made from split copper conduit which internal dia is 10 mm. To the right of the dipole there is a disc whose dia is L x 0.4 (= 49 mm) and distance from the dipole is again L/4. Disc material can be thin aluminum or tinned steel sheet.
At same distance as the disc, there is also a ring made from pvc-coated electric wire 1,5 mm2 by binding it to ring diameter about L x 2. It is not necessary to short the ends of the ring, I left ~ 1 mm space. If you want you can short the ends together as well. PVC coating on the wire has no magic, you can use e.g 2 mm clear copper wire as well.
I mounted the Disc and the Ring to the plastic cover made from microwave oven bulb. A piece of plastic sheet and glue are needed to mount the disk. The ring I glued inside the cover, so the diameter of the ring becomes somewhat smaller than L/4.
Visit Here for more.