<p><strong>Abstract.</strong> Quasi-perpendicular supercritical shocks are characterized by the presence of a magnetic foot due to the accumulation of a fraction of the incoming ions that is reflected by the shock front. There, three different plasma populations coexist (incoming ion core, reflected ion beam, electrons) and can excite various two-stream instabilities (TSIs) owing to their relative drifts. These instabilities represent local sources of turbulence with a wide frequency range

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... ding from the lower hybrid to the electron cyclotron. Their linear features are analyzed by means of both a dispersion study and numerical PIC simulations. Three main types of TSI and correspondingly excited waves are identified: <br><br> i. Oblique whistlers due to the (so-called <q>fast</q>) relative drift between reflected ions/electrons; the waves propagate toward upstream away from the shock front at a strongly oblique angle (<i>θ</i> ∼ 50°) to the ambient magnetic field <b><i>B</i></b>_<i>o</i>, have frequencies a few times the lower hybrid, and have wavelengths a fraction of the ion inertia length <i>c</i>∕<i>ω</i>_pi. <br>ii. Quasi-perpendicular whistlers due to the (so-called <q>slow</q>) relative drift between incoming ions/electrons; the waves propagate toward the shock ramp at an angle <i>θ</i> a few degrees off 90°, have frequencies around the lower hybrid, and have wavelengths several times the electron inertia length <i>c</i>∕<i>ω</i>_pe. <br>iii. Extended Bernstein waves which also propagate in the quasi-perpendicular domain, yet are due to the (so-called <q>fast</q>) relative drift between reflected ions/electrons; the instability is an extension of the electron cyclotron drift instability (normally strictly perpendicular and electrostatic) and produces waves with a magnetic component which have frequencies close to the electron cyclotron as well as wavelengths close to the electron gyroradius and which propagate toward upstream. <br><br> Present results are compared with previous works in order to stress some features not previously analyzed and to define a more synthetic view of these TSIs.</p>