Semi-Rigid Coax Selector Guide

P1dB semi-rigid coax is used to build semi-rigid assemblies for test equipment, aerospace, wireless, medical and low PIM applications.  The advantage of semi-rigid coax over flexible coax is its increased phase stability and lower insertion loss.  Semi-rigid coax also provides the best electrical isolation and lower noise levels when compared to flexible coax.

Another advantage of semi-rigid coax is that it can be bent into and hold intricate shapes to accommodate complex cable runs, such as inside a chassis.  Semi-rigid is very durable and can survive harsh shock and vibration environments, such as a jet fighter or a missile. It can also handle large temperature swings, depending on the coax dielectric.

P1db Semi-rigid is available in 10 Ohm, 17 Ohm, 25 Ohm, 50 Ohm, 75 Ohm and 93 Ohm impedances with solid PTFE, low-density PTFE (LD PTFE) or FEP dielectric.  The diameters available are .031 inch, .034 inch, .047 inch, .070 inch, .085 inch, .118 inch, .130 inch, .141 inch and .250 inch with a bare copper, tinned copper, silver plated copper, tinned aluminum or stainless steel outer conductor.  Two types of center conductors are offered, which are silver plated copper (SPC) easier bending or silver plated copper clad steel (SPCW) for high vibration applications.  All raw semi-rigid coax types are sold in straight sections, depending on the coax diameter.  Check the individual semi-rigid coax page for its specific straight-section length.

Semi-Rigid Features

• Impedance values from 10 to 93 Ohms
• Diameters from .031 inches to .250 inches
• Standard (PTFE and FEP) and low loss (LD PTFE) version
• Outer Conductor options from Bare Copper, Tinned Copper, Tinned Aluminum and more
• Semi-Rigid Coax is sold in 1 to 2-meter lengths, depending on the coax diameter

Phase-matched cables are offered in both flexible and semi-rigid coax, but semi-rigid offers the best performance and stability.  This is because semi-rigid coax will not flex, therefore phase-over-flexure errors on non-existent.  Their ability to hold a shape, phase stability and their high power capability are reasons why these cables are also preferred for coaxial baluns and transformers in applications, such as in a high power RF amplifier or pallet.

P1dB has a large selection of semi-rigid coax at a very competitive price.  The types of coax are shown below in 3 categories, .085 and .141 50 Ohm Coax, More 50 Ohm Coax Diameters, and Other Impedance Coax.  Our semi-rigid is broken into 3 groups below for your convenience. They are .085 and .141 50 Ohm coax, other 50 Ohm diameter coax, and other impedance coax.

.085 and .141, 50 Ohm Coax  - The most common diameters for semi-rigid cable assemblies, due to a wide selection of connectors.   A bare copper outer conductor is the most common type, but many customers prefer tinned copper for its solder-ability when assembling their own cables.  For situations where increased conductivity is needed, then Silver plated copper is the best choice.  Metals other than copper are also available, such as Tinned Aluminum for weight concerns and Stainless Steel for harsh environments.  There are two choices for a dielectric, PTFE for common applications and LD PTFE for low loss requirements.  

Part Number	Impedance (Ω)	Diameter (in.)	Outer Conductor	Center Conductor	Dielectric
P1CB-050-085-CUSP-L	50	.085	Bare Copper	SPC	LD PTFE
P1CB-050-085-CUSW-P	50	.085	Bare Copper	SPCW	PTFE
P1CB-050-085-SPSP-L	50	.085	Silver Plated Copper	SPC	LD PTFE
P1CB-050-085-SPSW-P	50	.085	Silver Plated Copper	SPCW	PTFE
P1CB-050-085-SSSW-P	50	.085	Stainless Steel	SPCW	PTFE
P1CB-050-085-TASP-L	50	.085	Tin Plated Aluminum	SPC	LD PTFE
P1CB-050-085-TASW-P	50	.085	Tin Plated Aluminum	SPCW	PTFE
P1CB-050-085-TPSP-L	50	.085	Tin Plated Copper	SPC	LD PTFE
P1CB-050-085-TPSW-P	50	.085	Tin Plated Copper	SPCW	PTFE
P1CB-050-141-CUSP-L	50	.141	Bare Copper	SPC	LD PTFE
P1CB-050-141-CUSW-P	50	.141	Bare Copper	SPCW	PTFE
P1CB-050-141-SPSP-L	50	.141	Silver Plated Copper	SPC	LD PTFE
P1CB-050-141-SPSW-P	50	.141	Silver Plated Copper	SPCW	PTFE
P1CB-050-141-SSSW-P	50	.141	Stainless Steel	SPCW	PTFE
P1CB-050-141-TASP-L	50	.141	Tin Plated Aluminum	SPC	LD PTFE
P1CB-050-141-TASW-P	50	.141	Tin Plated Aluminum	SPCW	PTFE
P1CB-050-141-TPSP-L	50	.141	Tin Plated Copper	SPC	LD PTFE
P1CB-050-141-TPSW-P	50	.141	Tin Plated Copper	SPCW	PTFE

More 50 Ohm Coax Diameters  – Higher frequency applications, such as 60 GHz, require smaller diameter coax cables with higher cutoff frequencies.   For example, a .047 diameter cable has a maximum frequency of 109 GHz, while a .250 diameter coax has a max frequency of 19 GHz.  The tr adeoff  is choosing as large of a diameter as possible to reduce insertion loss while not exceeding a coax cables max frequency. A popular use for small diameter coax is in pigtails for use as an RF probe within a circuit for testing purposes.

Part Number	Impedance (Ω)	Diameter (in.)	Outer Conductor	Center Conductor	Dielectric
P1CB-050-031-CUSP-L	50	.031	Bare Copper	SPC	LD PTFE
P1CB-050-031-TPSP-L	50	.031	Tin Plated Copper	SPC	LD PTFE
P1CB-050-034-CUSW-P	50	.034	Bare Copper	SPCW	PTFE
P1CB-050-034-SPSW-P	50	.034	Silver Plated Copper	SPCW	PTFE
P1CB-050-034-TPSW-P	50	.034	Tin Plated Copper	SPCW	PTFE
P1CB-050-047-CUSW-P	50	.047	Bare Copper	SPCW	PTFE
P1CB-050-047-SPSW-P	50	.047	Silver Plated Copper	SPCW	PTFE
P1CB-050-047-SSSW-P	50	.047	Stainless Steel	SPCW	PTFE
P1CB-050-047-TASP-L	50	.047	Tin Plated Aluminum	SPC	LD PTFE
P1CB-050-047-TASW-P	50	.047	Tin Plated Aluminum	SPCW	PTFE
P1CB-050-047-TPSW-P	50	.047	Tin Plated Copper	SPCW	PTFE
P1CB-050-070-CUSP-P	50	.070	Bare Copper	SPC	PTFE
P1CB-050-070-SPSP-P	50	.070	Silver Plated Copper	SPC	PTFE
P1CB-050-118-CUSW-L	50	.118	Bare Copper	SPCW	LD PTFE
P1CB-050-118-SPSW-L	50	.118	Silver Plated Copper	SPCW	LD PTFE
P1CB-050-118-TPSW-L	50	.118	Tin Plated Copper	SPCW	LD PTFE
P1CB-050-250-CUSP-P	50	.250	Bare Copper	SPC	PTFE
P1CB-050-250-SPSP-P	50	.250	Silver Plated Copper	SPC	PTFE
P1CB-050-250-TASP-P	50	.250	Tin Plated Aluminum	SPC	PTFE
P1CB-050-250-TPSP-P	50	.250	Tin Plated Copper	SPC	PTFE

Other Impedance Coax – Other impedance semi-rigid coax is commonly used to make baluns or transformers for high power applications, such as in an RF power amplifier. They are also used to feed antenna structures whose characteristic impedance may not be 50 Ohms. The broadcast industry widely uses 75 Ohm transmission lines for routing signals, so P1dB has a few 75 coax designs from which to choose.

Part Number	Impedance (Ω)	Diameter (in.)	Outer Conductor	Center Conductor	Dielectric
P1CB-010-034-CUSP-F	10	.034	Bare Copper	SPC	FEP
P1CB-010-043-SPSP-F	10	.043	Silver Plated Copper	SPC	FEP
P1CB-010-070-CUSP-F	10	.070	Bare Copper	SPC	FEP
P1CB-010-070-SPSP-F	10	.070	Silver Plated Copper	SPC	FEP
P1CB-017-034-CUSP-P	17	.034	Bare Copper	SPC	PTFE
P1CB-025-034-CUSW-P	25	.034	Bare Copper	SPCW	PTFE
P1CB-025-070-CUSP-F	25	.070	Bare Copper	SPC	FEP
P1CB-025-070-SPSP-F	25	.070	Silver Plated Copper	SPC	FEP
P1CB-025-070-TPSP-F	25	.070	Tin Plated Copper	SPC	FEP
P1CB-025-090-CUSP-P	25	.090	Bare Copper	SPC	PTFE
P1CB-025-125-CUSP-P	25	.125	Bare Copper	SPC	PTFE
P1CB-075-085-CUSW-P	75	.085	Bare Copper	SPCW	PTFE
P1CB-075-090-CUSP-F	75	.090	Bare Copper	SPC	FEP
P1CB-075-141-CUSW-P	75	.141	Bare Copper	SPCW	PTFE
P1CB-093-130-CUSW-P	93	.130	Bare Copper	SPCW	PTFE