Combining antennas and radios: splitters, hybrids, combiners, duplexers

Two or more antennas as one: power splitters

CompleTech's CS is a "2 to 1 power combiner / 1 to 2 power splitter" for 80–90 MHz up to 2412–2484 MHz, VSWR under 1.5. In CompleTech's list of uses: "combining multiple antennas", "building up distribution cable harness", "different splitting ratios by cascading", "no additional jumper cables or connectors required" and "minimizes the amount of junctions and losses". (ComAnt catalog, p. 67)^[1]

CompleTech describes ComAnt as modular: "combining basic products into countless different application products with different radiation pattern and gain." (ComAnt catalog, p. 1)^[1] The CS comes in the same frequency versions as the antennas; order the one that matches yours.

Two radios, one antenna: ring hybrids

CompleTech's RH ring hybrid is for "dual radios connected to a single antenna", "hot stand by same channel redundancy" and "adjacent channel simultaneous operation". Insertion loss is under 3.25 dB and isolation 30–70 dB, with four N-female ports. (ComAnt catalog, p. 76)^[1]

Several transmitters, one antenna: combiners

• Hybrid combiners can join transmitters on close or even identical frequencies, which cavity combiners cannot. The price is loss: each two-way hybrid stage loses at least 3 dB, so two channels lose at least 3 dB and four channels at least 6 dB, plus real-world losses.
• Cavity combiners lose less, but need channel spacing.

Transmit and receive on one antenna: duplexers

A duplexer lets a transmitter and a receiver share one antenna. It is tuned at the factory to your frequencies.

Antennas on the same mast: isolation

CompleTech's RK repeater kit adds "10 dB additional isolation between two antennas on the same vertical axis", in versions from 88–108 MHz to 830–890 MHz. (ComAnt catalog, p. 77)^[1] Tell us how many antennas share the mast and their frequencies, and we will suggest the spacing and parts.