The design of this antenna is made by Matjaz Vidmar (again!). It is a sort of dish antenna for the 1200 MHz (23 cm) and 2400 MHz (13cm) bands.
The antenna is composed by a metallic disc surrounded by a ring few centimeters high that works as main reflector closed on the front face by a plastic sheet. In the center of this cover it is glued an alluminum disc that works as a sub-reflector. Inside it is mounted the dipole.
This is the 13 cm version, seen in profile.
We have realised one version of the antenna for the 1200 MHz band using fiberglass for PCBs with different thickness, i.e. 2mm for the back disc and FR04 for the external ring and for the sub-reflector.
The dipole has been realised using semirigid cable for microwaves UT141. In place of the SMA connector we used an N-female connector panel mounted.
Here below you can finde two pictures of the antenna we realised.
The following figures show the dimensions and data needed to build the dipole and the balun. They are taken from an article published in ZRS on February 1996.
Thanks to the availability of the personnel of the time/frequency laboartory
of the IEN Galileo Ferraris of Turin it was possible to measure the antenna
We provide here below the plots derived from the measurements done with the network analyser.