Coax: The Critical LinkMIL-HDBK-216 published in 1962 Standardized RG and UG terminology in the...

Coax: The Critical LinkAs Presented: 2018 ARRL New England Convention

Boxborough, MA

By: Jeremy, KB1REQ

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

http://creativecommons.org/licenses/by-nc-sa/4.0/

Background on Coaxial Cable

Coax: The Critical Link ©2018 Jeremy Breef-Pilz

Why we use Transmission Line“When the length of the conductor is comparable to the wavelength of the signal, the conductor must be considered as a transmission line”

Transmission Lines allow us to have the same signal at various points in the RF network


Transmission Line Forms

http://slideplayer.com/slide/10648036/


Coaxial Transmission Line


Why we use Coaxial Transmission Lines

https://www.st-andrews.ac.uk/~jcgl/Scots_Guide/audio/part6/page3.html

VS.

https://blog.lamsimenterprises.com/2011/02/22/coaxial-transmission-line-geometry/


The model of a Transmission Line

https://www.intechopen.com/books/current-trends-and-challenges-in-rfid/radio-frequency-background


Impedance of Coaxial Transmission Line

● Given two coaxial lines made from the same materials and with the same diameter outer conductor

● The cable with the smaller diameter center conductor will have a higher impedance

● The cable with the larger diameter center conductor will have a lower impedance


Why 50 Ohms?Ideal Impedances:

● Power Handling: 30Ω● Voltage Handling: 60Ω● Low Energy Attenuation: 75Ω

Compromise Impedance:

● 50Ω

https://www.belden.com/blog/broadcast/50-ohms-the-forgotten-impedanceCoax: The Critical Link ©2018 Jeremy Breef-Pilz

RG “Radio Guide”

● MIL-HDBK-216 published in 1962

● Standardized RG and UG terminology in the industry


MIL-DTL-17● Released in 1970s,

currently Rev. J, 2014● More stringent standards

for Coax cables● Includes both legacy RG

cable and new designs


Properties of Coaxial Cables


Coax MaterialsCenter Conductor

● Copper, Aluminum, Steel, Silver

Dielectric

● Air, Polyethylene (PE), Polytetrafluoroethlyne (PTFE), Tetrafluoroethylene (TE)

Outer Conductor

● Copper, Aluminum, Silver

Jacket

● Polyvinyl Chloride (PVC), Cross-linked Polyolefin (XLPO), Polyethylene (PE), Thermoplasic Elastomer (TPE), Fluorinated Ethylene Propylene (FEP)


Construction TechniquesCenter Conductor

● Solid, Stranded, Plated

Dielectric

● Solid, Foamed, Taped

Outer Conductor

● Braided, Foil, plated

Jacket

● Flooded, Armored


Electrical Parameters● Nominal Impedance ( )● Maximum Frequency (GHz)● RF Loss (dB/distance @ ƒ)● Maximum RF Power (Watts @ ƒ)● Capacitance/Inductance (pico-F/distance) (micro-H/distance) ● Velocity Factor/Propagation Delay (%)● Maximum Voltage (V)


Mechanical Parameters● Dimensions● Minimum Bend Radius (distance) (single, repeated)● Weight (weight/distance)● Temperature range


Traditional Coax Cables


RG-58Can have a solid…

Standard: RG-58U

Center Conductor: 20AWG solid

Nominal Diameter: 0.193”

Minimum bend radius: 2”

RF Loss: 8.4dB/100’ @400MHz

★ 50 Watts in + 50’ of coax = 19.1 Watts out

Price: $0.30/ft.

(Belden 9201)

Or stranded center conductor

Standard: M17/28-RG058 (RG-58C/U)

Center Conductor: 20AWG stranded (19x33AWG)



RF Loss: 11.5dB/100’ @400MHz


Price: $0.32/ft.

(Belden 9203)


RG-8Standard: RG-8/U

Center Conductor: 13AWG stranded (7/21AWG)


Minimum bend radius: 4.05”

RF Loss: 6dB/100’ @400MHz

★ 50 Watts in + 50’ of coax = 25 Watts out

Price: $0.91/ft.

(Alpha 9008)

Standard: RG-8/U






Price: $1.35/ft.

(Belden 8214)


RG-213Standard: RG-213/U (M17/74, M17/163-00001)






Price: $1.00/ft.

(Belden 8267)

Difference between RG-8 and RG-213?


RG-8XStandard: N/A






Price: $0.55/ft.

(Belden 8267)


RG-174Standard: RG-174/U




RF Loss: 19dB/100’ @400MHz


Price: $0.17/ft.

(Belden 8216)

A dual-band “Mini-Magmount” antenna with 9 ft of RG-174 cable,

Will see 2.7 Watts from a 4 Watt HT on 70cm


Lower Loss Designs


The first attempt… Belden 9913

Major Risk: Water intrusion

Standard: N/A

Center Conductor: 10 AWG solid



RF Loss: 2.6 dB/100’ @400MHz


Price: $0.90/ft.


LMR-400Environmental variants:

● DB - Direct Burial (watertight)● FR - Fire Retardant (riser)● PVC - PVC Jacket

Standard: N/A

Center Conductor: 10AWG Solid





Price: $0.94/ft.


LMR-400-UFULTRAFLEX

Standard: N/A

Center Conductor: 10AWG Stranded



RF Loss: 3.2 dB/100’ @400MHz


Price: $1.34/ft.


Popular sizes:

● LMR-600● LMR-400 (RG-8 Size)● LMR-300● LMR-240 (RG-8X Size)● LMR-200● LMR-195 (RG-58 Size)● LMR-100 (RG-174 Size)


LMR-240Standard: N/A




RF Loss: 5.1 dB/100’ @400MHz


Price: $0.64/ft.


LMR-240-UFStandard: N/A

Center Conductor: 16AWG Stranded



RF Loss: 6.1 dB/100’ @400MHz


Price: $0.83/ft.


Lower Loss Where?


LMR-195Standard: N/A




RF Loss: 7.4 dB/100’ @400MHz


Price: $0.51/ft.


LMR-100AStandard: N/A




RF Loss: 15 dB/100’ @400MHz

★ 50 Watts in + 50’ of coax = 10 Watts out

Price: $0.55/ft.


From Other Manufacturers:Belden - RF400

Andrew/Commscope - CNT400

Commscope - WBC400

Coleman - Signawave 400

Carol - DBRF400


A word of Caution...None of the Cables listed in this section are suitable for use in repeaters or other duplex applications

The galvanic dissimilarity of the AL foil and the CU braid accelerates oxidation which creates a non-linear junction within the outer conductor of the cable.

This non-linear junction becomes and RF mixing point.


Silver Plated Coax


Do I need Silver Plated Cable?● Duplex Applications

○ In-band receiver active at the same time as one or more transmitter(s)

● High RF Power Levels● High Temperatures● Microwave Frequencies

Cables with silver =/= Low Loss cables


RG-142Standard: M17/60-RG142




RF Loss: 7.9 dB/100’ @400MHz


Price: $3.27/ft.






RF Loss: 8.8 dB/100’ @400MHz


Price: $2.67/ft.



Center Conductor: 19AWG Stranded (19x32AWG)



RF Loss: 8.7 dB/100’ @400MHz


Price: $3.24/ft.






RF Loss: 4.1 dB/100’ @400MHz


Price: $2.84/ft.






RF Loss: 4.8 dB/100’ @400MHz


Price: $9.38/ft.






RF Loss: 17.5 dB/100’ @400MHz


Price: $2.00/ft.



Hardline


Heliax Numbering● 1 - ¼”● 2 - ⅜”● 4 - ½”● 4.5 - ⅝”● 5 - ⅞”● 6 - 1 ¼”● 7 - 1 ⅝”


LDF Cable“Low Density Foam”

Replaced by AVA Cable

LDF4-50A

Center Conductor: 0.190” Solid

Nominal Diameter:0.625”


RF Loss: 1.36 dB/100’ @400MHz


Price: $1.98/ft.


FSJ CableFSJ1-50A




RF Loss: 3.7 dB/100’ @400MHz


Price: $1.27/ft.

FSJ4-50B




RF Loss: 2.2 dB/100’ @400MHz


Price: $2.85/ft.


Consideration Points

● Acceptable RF Loss● Diameter● Repeated Flexure or Vibration● Total cost

○ Cost of cable and connectors○ Cost of replacing in the event of a failure


Names To Know:


References RG to M17 Cross Reference

Max. Attenuation, Power and Frequency for M17 Cables

Times Microwave Cable Properties Calculator

Watts to dBm Calculator


http://catalog.standard-wire.com/Asset/Coax-Cable-Cross-Reference.pdf

http://catalog.standard-wire.com/Asset/MIL-DTL-17-Attenuation.pdf

http://www.timesmicrowave.com/calculator/

https://www.everythingrf.com/rf-calculators/watt-to-dbm

Date post:	21-Jun-2021
Category:	Documents
Upload:	others
View:	3 times
Download:	0 times

Coax: The Critical LinkMIL-HDBK-216 published in 1962 Standardized RG and UG terminology in the...

Documents