A plasma has been produced in 0.1–0.3 mTorr Ar inside a rectangularTE10mode waveguide with a cross-sectional area (6.3 cm width × 4.2 cm height) much smaller than standard waveguides (12.4 cm width ×5.6 cm height), using microwaves of 2.45 GHz and 100–260 W of power. The characteristics of the plasma and the wave propagation have been studied for the perpendicularly launched waves(k⊥B)in the ordinary like(E∥B)and extraordinary like(E⊥B)modes, where a magnetic field of about 1200 G is generated inside the waveguide by rectangular blocks of permanent SmCo magnets. The maximum electron density, as measured by a plane probe, in theE∥BandE⊥Bcases are2×1010and3×1011 cm−3,respectively, while the electron temperatures ranged between 3 and 11 eV. Experimental results obtained in the two cases are discussed and the particle trajectories are studied from a single particle theory. ©1997 American Institute of Physics.