— Installer Guide · MIMO 4G · Dual-Port Communicators
MIMO 4G Antenna
Dual-Port Alarm Guide
Alarm communicators with two antenna ports (MIMO) require two physically separated external antennas — not one. Single-antenna installations on dual-port devices disable MIMO and leave significant signal margin on the table. This guide covers the correct MIMO kit, mounting rules, and bulk supply options for security installers.
MIMO 2×2
Dual Antenna
≥50 cm
Separation Required
Both ports
Must Connect
50Ω
VSWR Tested
Dual-port alarm communicators — MIMO devices
All devices below require two external antennas for full MIMO operation.
Permaconn PM54
Most common dual-port 4G alarm communicator in Australia. Two SMA Female ports labelled ANT1 and ANT2 (or MAIN and DIV). Both ports must be connected for MIMO to function — leaving one port open halves MIMO performance and may fail carrier certification. Requires 2× DG900MB-HG or 2× DG850MB-MINI-CT with 50 cm minimum separation.
Permaconn PM54-4G MIMO
4G MIMO variant of the PM54. Same two SMA Female antenna ports. The PM54 is the most widely installed communicator in Australian alarm systems — any upgrade to external antennas requires a MIMO kit, not a single antenna.
Any dual-SMA 4G communicator
Any 4G alarm communicator with two SMA Female ports requires a MIMO antenna kit. The two antenna ports implement diversity receive (MIMO 2×2) — both must be connected with physically separated antennas to achieve the MIMO link budget improvement. Single-antenna installations connected to one port only revert to SISO mode.
D&G MIMO antenna kits
Supplied as matched pairs. Use DG900MB-HG kit for outdoor/high-gain installs; DG850MB-MINI-CT kit for enclosures and compact mounting.
MIMO Kit — 2× DG900MB-HG (High Gain Outdoor)
Primary MIMO kit for outdoor and high-gain installations. Two DG900MB-HG antennas mounted at minimum 50 cm spacing — one for ANT1/MAIN, one for ANT2/DIV. Both antennas connect via their 5 m SMA Male cables directly to the communicator's SMA Female ports. Polarisation diversity: mount one antenna vertical, one horizontal to maximise MIMO gain. IP67 rated for permanent external mounting.
MIMO Kit — 2× DG850MB-MINI-CT (Compact Indoor/Enclosure)
Compact MIMO kit for space-constrained enclosures or indoor installations. Two DG850MB-MINI-CT antennas (160 mm × Ø14 mm). Mount one inside top of enclosure, one outside via cable gland — this physical separation provides diversity even in confined spaces. Or both externally with 50 cm spacing on an external wall bracket. IP54 rated.
MIMO Extension Kit — 2× SMA Male to SMA Male pigtails
For routing the MIMO kit antennas away from the communicator. Two 30 cm SMA Male–Male pigtails extend reach without additional cable loss. For longer runs (through conduit, to external mounts), specify custom length SMA Male–Male assemblies. Available in LMR200 (up to 5 m) or LMR400 (5–15 m) for low-loss long runs.
MIMO installation rules
Minimum 50 cm physical separation
MIMO antennas must be physically separated to experience different multipath environments. Less than 50 cm reduces spatial diversity gain — the MIMO system cannot distinguish independent signal paths. For panel enclosures where 50 cm is impossible, use one internal and one external antenna through a cable gland.
Both ports must be connected
A dual-port communicator with one port left open or terminated loses MIMO entirely and may fail network registration in some configurations. Always connect both ANT1/MAIN and ANT2/DIV ports. The communicator's internal diversity algorithms require both antennas to be active.
Polarisation diversity (optional, increases gain)
Mount one antenna vertically polarised (standard upright) and one horizontally polarised (tilted 90°) to capture orthogonal polarisation paths as well as spatial diversity. In a typical urban site with rich multipath, polarisation diversity adds 2–4 dB effective gain vs two identically polarised antennas.
Same cable length on both ports
For best MIMO performance, keep cable lengths matched between ANT1 and ANT2. More than 2 m difference in cable length between ports creates a timing skew that can reduce MIMO efficiency in 4G LTE Category 4 and above modems. Not critical for Category 1 communicators.
Deployment scenarios
Permaconn PM54 — metal enclosure, commercial premises
PM54 installed in a steel switchboard. Both SMA Female ports on the PM54 connected to 5 m SMA Male cables from two DG900MB-HG antennas. Antennas mounted externally on the switchboard surface at 60 cm spacing, one vertical one horizontal polarisation. Result: dual-path MIMO signal in an enclosure that previously had zero GSM registration with the factory stub.
PM54 — basement plant room, long cable run
PM54 in a plant room 3 floors below street level. Both antenna ports connected via custom LMR400 15 m assemblies (SMA Male each end) routed through conduit to two DG900MB-HG antennas on the external building facade at street level. At 15 m, LMR400 introduces 0.95 dB loss at 850 MHz — well within the PM54's link budget. Both antennas mounted at 60 cm spacing on the facade.
Dual-SMA communicator — high-rise apartment block
High-rise common areas often have partial cellular coverage from indoor DAS systems plus direct rooftop signal. MIMO antenna diversity performs well in these multi-path environments. Two DG850MB-MINI-CT antennas, mounted in the ceiling of the comms room at 60 cm spacing (one each side of the rack), provide diversity paths through the ceiling and wall structures to different parts of the DAS system.
Bulk MIMO kit supply — security installer volume order
D&G supplies MIMO kits to security installers as matched pairs — two DG900MB-HG or two DG850MB-MINI-CT, pre-tested and paired, with a cable identification tag on each to prevent ANT1/ANT2 mix-up on site. Bulk pricing from 50 pairs (~35% off RRP). OEM kits with custom labelling and packaging available from 100 pairs. Call 02 4732 3083 or submit a bulk quote request.
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