Re: NEC-LIST: High gain antenna for EMC testing

Dear Ayhan,

Several years ago we had a lot of problems with EM Susceptibilty
testing of large equipment. The main problem is the dipole-like
antenna's used for EMC testing, such as the biconical or the
log-periodic. The advantage of these antenna's is that we, EMC
engineers, can compare these antennas with the general dipole model of
the equipment under test, i.e. the EUT is modelled as a dipole. But:
The linear antennes will give an antenna pattern increase in one
direction (doughnut). A square antenna type would be better because it
gives an increased gain in two directions. Furthermore such an antenna
is less sensitive for metal planes placed nearby (metal floor).
Therefore we use a Double Ridged Guide (DRG) antenna. These antennas
are available in 200MHz-1GHz and 1-10GHz ranges. About 5 years ago I
advised a automotive lab in North-West Europe. They experienced the
same problem as described by you. By using the DRG instead of the
log-per antenna the problems were solved.

We have been searching for a DRG for the frequency range 80MHz-1GHz
too, but could not find an excisting antenna. It had to be designed
first, but we did not receive a commercially attractive
offer. Therefore we designed the Extended DRG, for 80MHz-1GHz,
ourselves. A paper has been published at the IEEE EMC Symposium,
Denver, 1998, including measurement results, showing a higher gain
between 90MHz-1GHz than the biconical and the log periodic antennas. I
will send you a PDF version of the paper.

Note: the Extended DRG has not been protected by a patent. Drawings
are available. Our company is not interested in selling EMC test
equipment, but we can give you the address of two companies interested
in producing and selling the antenna.

Greetings,

Frank Leferink
Sr. EMC Consultant Thomson-CSF-Signaal, The Netherlands
Ass. professor EMC, University of Twente

Gunsaya, Ayhan (A.) wrote:
>
> We are trying to design/purchase a (or a set of) high gain antenna for
> automotive EMC testing. The basic requirement is to generate 200 V/m
> in a frequency range of 200MHz to 1GHz, at a distance of 1m, using
> 400W. We currently have several low gain antenna (in the range of
> 5dBi ) and I estimate that increasing the antenna gain to around 10dBi
> (measured at a distance of 1 m not in the far field) will give
> sufficient results....
Received on Sat May 13 2000 - 11:05:05 EDT