A discone antenna is a vertically polarized, broad bandwidth antenna. A
quadrifilar helix is a circularly polarized, relatively narrow bandwidth
antenna. About the only thing they have in common is that both are
omnidirectional in azimuth. A quadrifilar helix is a more suitable
antenna for receiving the circularly polarized, relatively narrow
bandwidth signals from a weather satellite.

Roy Lewallen, W7EL

Thierry wrote:
Hi,

To pick up a 137 MHz signal from wx satellite (POES), are the discone and
quadrifilar helix antennas similar, I mean, they are different in design but
for the rest ?
Are they both omnidirectional and are they both able to change automatically
the elevation and azimuth to the satellite direction without interruption
and without requiring a rotator ? or only the helix provides this capability
?

Thanks in advance

Thierry, ON4SKY
http://www.astrosurf.com/lombry