In this paper we present new and archive radio measurements obtained with the
Very Large Array of the magnetic chemically peculiar (MCP) star \sigma Ori E.
The radio data have been obtained at different frequencies and are well
distributed along the rotational phases. We analyze in detail the radio
emission from \sigma Ori E with the aim to search evidence of circularly
polarized radio pulses. Up to now, among the MCP stars only CU Virginis shows
100% polarized time-stable radio pulses, explained as highly directive electron
cyclotron maser emission, visible from Earth at particular rotational phases,
like a pulsar. Our analysis shows that there is no hint of coherent emission at
frequencies below 15 GHz. We conclude that the presence of a quadrupolar
component of the magnetic field, dominant within few stellar radii from the
star, where the maser emission should be generated, inhibits the onset of the
cyclotron maser instability in \sigma Ori E.Comment: 10 pages, 5 figures, accepted for publication in MNRA
