The frequency-tunable differentially fed rectangular dielectric resonator antenna (DRA) loaded by chip capacitors or chip varactors is investigated. Two conducting strips are attached on two opposite DRA side walls for soldering the loading elements. In each loading case, a frequency-tunable DRA with good match and stable radiation patterns can be obtained. Also, the cross-polarized field level is relatively low. Reasonable agreement between the measured and simulated results is obtained. It is found that the frequency tuning ratio can be controlled by the loading elements and the sizes of the DRA and conducting strips. In particular, for the varactor-loaded case, a frequency-reconfigurable DRA can be obtained by varying the biasing voltage of the varactors.