A standing wave oscillator to generate at least one voltage standing wave, comprising a closed-loop coplanar stripline including two conductors, and at least one amplifier disposed between the two conductors at a first location. The two conductors are connected together at a second location different from the first location to provide a zero voltage node for the at least one voltage standing wave. One or more of a tailored distributed amplification scheme, a plurality of linear conductive strips disposed in proximity to the coplanar stripline, and a tapered coplanar stripline configuration may be used with the closed loop structure. A particular amplifier configuration involving cross-coupling of the coplanar stripline conductors may be employed to facilitate single mode operation, using a particular resonator topology so as to avoid inducing significant loss in the oscillator.