A HE.sub.0.gamma..delta. mode dielectric resonator (12) includes a
cylindrical dielectric disk (32) having top and bottom ends (20, 22)
spaced apart by a closed curve wall (24). The dielectric disk (32) has a
dielectric constant greater than 40. An axially aligned hole (36) is
formed through the disk (32) between the top and bottom ends (20, 22). A
conductive wall (34) is formed at the closed curved wall (24) but not the
top and bottom ends (20, 22). The hole (36) has a preferred diameter less
than 0.2 times the diameter of the disk. A tuning plug (30) is formed from
a material having a dielectric constant less than 0.5 times the dielectric
constant of the dielectric disk (32) and an unloaded quality factor
greater than 2.0 times the unloaded quality factor of the dielectric disk
(32). The tuning plug is inserted to a desired depth within the hole (36)
of the dielectric disk (32).
