A modular filter system (100, 300, 800), comprising: a front panel (106, 306) and a back panel (111, 311); a multiband combiner (104, 304, 804) coupled to the front panel (106, 306), wherein the multiband combiner (104, 304, 804) comprises an antenna connector and a plurality of filter connectors, wherein the multiband combiner (104, 304, 804) has a passband filter for each filter connector of the plurality of filter connectors of the multiband combiner (104, 304, 804); a plurality of filter modules (102, 302, 802) separate from the multiband combiner (104, 304, 804), wherein each filter module (102, 302, 802) of the plurality of filter modules (102, 302, 802) includes a first connector configured to pass a first frequency band, a second connector configured to pass a second frequency band, and a combiner connector configured to pass the first frequency band and the second frequency band, wherein each filter module (102, 302, 802) of the plurality of filter modules (102, 302, 802) is configured to duplex, combine, or split first signals in the first frequency band and second signals in the second frequency band, wherein the combiner connector of each filter module (102, 302, 802) of the plurality of filter modules (102, 302, 802) is coupled to a respective filter connector of the plurality of filter connectors of the multiband combiner (104, 304, 804) by a respective cable of the modular filter system (100, 300, 800), wherein the multiband combiner (104, 304, 804) is configured to have wider passbands for the connectors to enable a flexibility for swapping out filter modules (102, 302, 802) configured to duplex, combine, or split different frequency bands; and a fixing system comprising a plurality of bars and a plurality of plates (108, 309), wherein the plurality of bars is coupled to the front panel (106, 306) and the back panel (111, 311) by respective fasteners of the modular filter system (100, 300, 800), wherein the plurality of bars and the plurality of plates (108, 309) are configured to secure the plurality of filter modules (102, 302, 802) between the multiband combiner (104, 304, 804) and the back panel (111, 311). a front panel (106, 306) and a back panel (111, 311); a multiband combiner (104, 304, 804) coupled to the front panel (106, 306), wherein the multiband combiner (104, 304, 804) comprises an antenna connector and a plurality of filter connectors, wherein the multiband combiner (104, 304, 804) has a passband filter for each filter connector of the plurality of filter connectors of the multiband combiner (104, 304, 804); a plurality of filter modules (102, 302, 802) separate from the multiband combiner (104, 304, 804), wherein each filter module (102, 302, 802) of the plurality of filter modules (102, 302, 802) includes a first connector configured to pass a first frequency band, a second connector configured to pass a second frequency band, and a combiner connector configured to pass the first frequency band and the second frequency band, wherein each filter module (102, 302, 802) of the plurality of filter modules (102, 302, 802) is configured to duplex, combine, or split first signals in the first frequency band and second signals in the second frequency band, wherein the combiner connector of each filter module (102, 302, 802) of the plurality of filter modules (102, 302, 802) is coupled to a respective filter connector of the plurality of filter connectors of the multiband combiner (104, 304, 804) by a respective cable of the modular filter system (100, 300, 800), wherein the multiband combiner (104, 304, 804) is configured to have wider passbands for the connectors to enable a flexibility for swapping out filter modules (102, 302, 802) configured to duplex, combine, or split different frequency bands; and a fixing system comprising a plurality of bars and a plurality of plates (108, 309), wherein the plurality of bars is coupled to the front panel (106, 306) and the back panel (111, 311) by respective fasteners of the modular filter system (100, 300, 800), wherein the plurality of bars and the plurality of plates (108, 309) are configured to secure the plurality of filter modules (102, 302, 802) between the multiband combiner (104, 304, 804) and the back panel (111, 311).