In this paper, a new class of microstrip filter with dual-band lowpass/bandpass response is reported. It consists of a periodic-type circuit configuration made up of an original firstorder double-band lowpass/bandpass filtering cell. The operating principle of this lowpass/bandpass filter structure is explained, and guidelines for its systematic design are expounded. Besides, a four-stage prototype with 60-dB inter-band Long-Term-Evolution (LTE) service rejection is designed and simulated at the layout level for verification. This dual-function filter approach can find use in next-generation multi-purpose communications systems simultaneously operating for several standards, such as those handling UHF DVB-T signals - lowpass band - and other services - passband(s) - along with LTE interference mitigation.