Antisymmetric multi cavity resonator useful for flat top transmission is reported which is simple and compact than the similar conventional structures. The study of the output spectra is carried out in terms of layer thickness and change in angle of incidence. Electro-optic property of the EO polymer is utilized to convert flat-top output with full width half maximum (FWHM) bandwidth of 10 nm into narrowband output of 0.64 nm (FWHM bandwidth) by applying a maximum voltage of 500 V across the structure. It was shown here that by controlling the low index layer widths, angle of incidence of the light and applying a voltage of 300 V results in a flattop spectrum of FWHM bandwidth of 2.5 nm with tuning sensitivity 0.033 nm/V. The tuning sensitivity and bandwidth of the reported hybrid filter can also be customized comparatively at lower applied voltage than the previously reported electro-optically tunable filters. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.