The resonance equation for the odd resonant frequencies of the widely used loop hairpin resonator tunable by capacitance is obtained. This equation allowed us to analyze the ratio of the first parasitic and fundamental resonance frequencies of this resonator, ${f} _{ {1}}/{f} _{ {0}}$ , on which the filter stop band depends. It is established that the values of ${f} _{ {1}}/{f} _{ {0}}$ for loop hairpin and combline resonators are close to each other with reduced electric lengths. This made it possible to combine two loop hairpin resonators and two combline resonators in one fourth-order microstrip bandpass filter, which retained a wide stop band, but the frequency response became more symmetrical. The design of a narrow-band (FBW = 0.025) filter of the fourth-order with loop hairpin and combline resonators was performed, where the filter could be tuned in the range of 225–400 MHz. The symmetry factor of the frequency response of this filter is analyzed. The designed example with the simulation and measurement results are presented.