Design guidelines Ultra Low Loss cable assemblies.

Transcription

1

2 Chapter Title 1. Selection criteria for high frequency coaxial cables 1.1 Cable specifications 2. Selection criteria for high frequency connectors 2.1 Assembly V.S.W.R. for typical configurations 2.2 Power derating for altitude and temperature 3. Cable assembly codification 4. Basic high frequency formulas

3 1. Selection criteria for high frequency coaxial cables The recommended high frequency coaxial cable family is selected by the cable selection chart for mechanical properties. The specific cable is selected on the electrical properties and diameter. SELECT A CABLE Flexlife Crush resistance Frequency range Insertion loss Power Diameter/Bending radius

4 1.1 Cable specifications

5 2. Selection criteria for high frequency connectors The recommended high frequency connector type is selected by the connector selection chart by frequency range. SELECT A CONNECTOR Frequency range Male/Female Straight/90 degrees/swept Power handling Mechanical properties

6 2.1 Assembly V.S.W.R. for typical configurations Assembly V.S.W.R. or return loss is influenced to a large extent by the specific assembly configuration (length and connector types) in combination with the frequency and bandwidth. Also the test method and equipment in use can have some influence. Because of that it is impossible to provide a single V.S.W.R. specification that would be applicable to all possible combinations of cables and connectors. However the following table can be used as a guideline. The mentioned values (table 1) apply to the standard connector series SMA, TNC and Type N in the precision or higher frequency versions of these series. When specific assembly requirements and test methods have been fixed, it is often possible to guarantee lower V.S.W.R. values. Also some connector and/or length combinations (extremely short or extremely long) may result in higher values. To be certain please contact us with your specific requirements. Table 1 Frequency Range (GHz) Cable Assembly V.S.W.R. Straight / Swept Connectors Two Angle Connectors Mixed Connectors Guar. Typical Guar. Typical Guar. Typical DC to (1.10) 1.25 (1.15) 1.20 (1.10) 2 to (1.10) 1.30 (1.20) 1.25 (1.20) 4 to (1.20) 1. (1.30) 1.35 (1.30) 8 to (1.25) 1.45 (1.35) 1. (1.35) 12 to (1.25) 1.45 (1.35) 1. (1.35) 16 to (1.25) 1.45 (1.35) 1. (1.35) 18 to (1.35) 1.55 (1.45) 1.50 (1.) 26.5 to 65 Call us for details

7 2.2 Power derating for altitude and temperature The power handling of microwave connectors is depending on the frequency, ambient temperature and altitude. In the below graphs the power handling of the most commonly used microwave connectors on sea level at 20ºC is shown and the derating factors for altitude and temperature. HN NP TNCP SMA 7 mm 3.5 mm K 2.4 mm Frequency (GHz.) Altitude (10³ meters) Ambient Temperature ( C)

8 3. Cable assembly codification assembly range C D G Customer specific assembly ALPEN standard stock assembly Gigalink standard stock assembly cable A 24 UFP A UFP A 50 UFP A 81 UFP A 150 UFP A 26DT FP A 52 FP A 80 FP A 120 FP A 180 FP A 26SDT TFE A 26 TFE A 52 TFE A 60 P A 80 P A 90 P A 120 P A 180 P A 250 P A 60 PPP A 90 PPP protection no protection flexible spring with PUR jacket (GP) flexible hose (FN) flexible hose with PUR jacket (FG) other range connector 1 & 2 A B C D DQ E F G H range 2,4mm K(2,9mm) 3,5mm SMA BMC TNCP NP AP7 freq , I J K L M N O P Q range MCX BMA SSMA SMB BNC SMP MMCX 7/16 freq , ,5 R S T U V W X Y Z range SSIS C SC HN SMC freq type male straight male swept male 90 deg other type connector 1 & type female straight screw female straight flange female swept female straight other

9 4. Basic high frequency formulas 1) Insertion losses Loss (db) = 10 log ¹º (P out/p in) 10 db = 10 % of P in lost 20 db = 1 % of P in lost 30 db = 0.1 % of P in lost 2) Return losses (VSWR) Losses due to reflected power Return loss (db) = 10 log ¹º (P in/p reflected) Return losses (db) VSWR ) Cut off frequency Maximum frequency of signal propagation versus the cable dimensions F max = 191 (d+d) Ep d = diameter inner conductor D = diameter dielectric Ep = dielectric constant