Lens antenna-coupled detectors have emerged as a prominent technology for future millimeter-wave astronomy, particularly in observing Cosmic Microwave Background (CMB) B-Mode. Given this context, we reconfigured the conventional broadband bowtie slot antenna into a double flare angle design, targeting CMB emission wavelengths centered at 150 and 220 GHz. This antenna exhibits a return loss S11 < −10 dB over more than an octave 100 - 300 GHz and delivers a bandwidth exceeding 20% for the two targeted sub-bands. When integrated with a dielectric lens, it retains effective linear polarization sensitivity, with cross-polarization below -15 dB at both sub-bands. Incorporating on-chip bandpass filters enables the separation of the antenna’s signals to microwave kinetic inductance detectors (MKIDs), constructing a compact, polarization-selective, multichroic pixel.