CIRF4x16

4x to 16x RF splitter/combiner, plus digitally controlled attenuation.

Up to four modem banks may be connected on one side, with up to four base stations on the other side. The signal routed to and from each base station may be individually attenuated, so as to test operating under varying conditions and to trigger handover.

Views

CIRF4x16 Rear Panel.

CIRF4x16 Internal.

Theory of operation

Up to four base stations may be connected via a 4-channel digitally controlled RF attenuator, which is in turn cabled to a 1:4 RF splitter/combiner, with a single connection from this to a front panel mounted SMA connector.

Up to sixteen cellular modems may be connected, via four groups of four, with each group connected to a 1:4 RF splitter/combiner + attenuation. The resulting four RF paths are then connected to another 1:4 RF splitter/combiner, following which a single connection from this to a second front panel mounted SMA connector.

In typical operation a link is connected across the two front panel SMA connectors, bridging the two networks. However, this link may be removed in order to allow other equipment to be inserted into the RF path, such as a fading simulator, for example.

A single CIRF4x16 may support up to four base stations plus sixteen cellular modems in SISO operation, and two units may be used for 2x2 MIMO etc.

Bill of materials

CIRF4x16 BOM

Component	Description	Manufacturer	Man. Part	Distributor	Dist. Part
Enclosure	1U Rack-mount enclosure	nVent SCHROFF	20860122	Farnell	1455925
D1	Panel mount LED indicator, green	RS Pro	205-331	RS Components	205-331
R1	330 ohm 0.25W 5% axial resistor	RS Pro	707-7622	RS Components	707-7622
J1	Male panel mount XLR connector	Neutrik	NC3MD-LX-M3	Mouser	568-NC3MD-LX-M3
J2	2.5x5.5mm barrel plug	RS Pro	487-854	RS Components	487-854
J3-J4	3-contact female box header	Harwin	M20-1060300	RS Components	681-2821
CBL1-16	U.FL to SMA female bulkhead	RF Solutions	CBA-UFLSMA20	RF Solutions	CBA-UFLSMA20
CBL17-20	SMA female bulkhead to SMA male 75mm	Taoglas	CAB.0114	Mouser	960-CAB.0114
CBL21-24	SMA female to right-angle MCX male	RF Solutions	CBA-SMAF-MCXMR	RF Solutions	CBA-SMAF-MCXMR
CBL25-26	Right-angle SMA male to SMA female bulkhead	Wurth Elektronik	65503603215303	Mouser	710-65503603215303
CBL27-30	Right-angle SMA male to right-angle SMA male	Crystek Corporation	CCSMA2-MM-RG174-12	Mouser	549-SMA2-MM-RG174-12
CBL31	Semi-rigid 2” SMA male to male jumper	Mini-Circuits	086-2SMR+	Mouser	139-086-2SMR
M1	Four-channel digitally controlled step attenuator	Sysmocom	sysmoRFDSATT-4-62	Sysmocom	sysmoRFDSATT-4-62
M2-3	1:4 splitter/combiner	e-meca	804-S-1.900-MO1
M4-7	1:4 splitter/combiner + attenutation	Sysmocom	rfcomb4r-att	Sysmocom	rfcomb4r-att
M8	Console IO board	LibreCellular	CONIO-B
Misc.	SMA male to SMA male right-angle adapter	RF Solutions	ADP-SMAM-SMAM90	RF Solutions	ADP-SMAM-SMAM90
Misc.	Female crimp terminals for Harwin M20 series	Harwin	M20-1180042	RS Components	681-2878
Misc.	22awg hook-up wire to build signal harnesses

Resources

• Mechanical design and graphics.