The Design & Test of Broadband Launches up to 50 GHz on Thin & Thick Substrates
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The Performance Leader in Microwave Connectors The Design & Test of Broadband Launches up to 50 GHz on Thin & Thick Substrates Thin Substrate: 8 mil Rogers R04003 Substrate Thick Substrate: 30 mil Rogers R04350 Substrate Southwest Microwave, Inc. www.southwestmicrowave.com

Southwest Microwave, Inc. The Design and Test of Broadband Launches up to 50 GHz on Thin and Thick Substrates Thin Substrate: 8 mil Rogers RO4003 Substrate Thick Substrate: 30 mil Rogers RO4350 Substrate Bill Rosas, Product Engineering Manager, Southwest Microwave, Inc. Copyright © 2011 by Southwest Microwave, Inc. and Bill Rosas. All rights reserved. Petra Microwave®, Ltd., Rogers Corporation®, CST ®-Computer Simulation Technology, and CST Microwave Studio® 2006 are all registered trademarks of their respective companies. Southwest Microwave, Inc. • Tempe, Arizona 85284 USA • 480-783-0201...

SOUTHWEST MICROWAVE Table of Contents Purpose 2 Southwest Microwave End Launch Connectors 3 End Launch Connector Features 4 Relative Sizes of the End Launch Connectors 5 Test Equipment and Techniques 6 SMI Format of S-parameter Data 6 Comparison of Straight Microstrip, Top Ground Microstrip and GCPWG 7 An Example of Launch Optimization 8 Original Test Board Design 8 Time Domain (TDR) Test data 8 Optimized Taper (Version 2) 11 Optimized Boards - Final Layouts 12 Loss (Straight Microstrip) 14 Loss (Top Ground Microstrip) 16 Advantages of Top Ground Microstrip on 30 mil Boards 18 Appendix Loss...

Purpose Customers often contact Southwest Microwave wanting to know why there are four different pin sizes on the end launch connector. The purpose of the paper is to explain that they are needed to optimally match the connector to different substrate thicknesses. As a result of our study of 50 GHz transmission lines and launches, 1” SMI has determinded that the practical range of substrate thicknesses of Rogers 4000 series material that are optimizable are 8 mil to 30 mil. Substrates that are thinner than 8 mil have line widths that are too small to optimize the launch with a taper for...

Southwest Microwave End Launch Connectors Connector Models The connectors used are SMI end launch connector assemblies, model numbers 1492-02A-5 and 1492-04A-5. These connectors were designed for single-layer boards and multi-layer boards where the top layer is the microwave layer. The 1492-02A-5 has a 2.4 mm female connector, a transition block with a 10 mil diameter circuit launch pin, and a 63.5 mil diameter coaxial ground with a center conductor of 20 mil. The 1492-04A-5 has a 2.4 mm female connector, a transition block with a 5 mil diameter circuit launch pin, and a 29 mil diameter...

End Launch Connector Features ► Southwest Microwave end Launch connector assemblies, model number 1492-02A-5 and 1492-04A-5. ► Used on single-layer boards. Used on multi-layer boards where the top layer is the microwave layer. Usable with any board thickness. Substrate (8 mil) .005 Substrate (30 mil) Launch Pin Ground Conductor Southwest Microwave, Inc. • Tempe, Arizona 85284 USA • 480-783-0201 • www.southwestmic

Relative Sizes of the End Launch Connectors These views show the relative sizes of the pins and the substrates. They illustrate how the larger pin matches with the thicker substrate and the smaller pin matches to the thinner substrate. The previous page shows side views with dimensions on the relative pin lengths and connector body overhang on to the board. This page shows a rear view with dimensions of the diameters of the connector launch and the substrate thickness. .064 .020 .010 Substrate (8 mil) .005 Substrate (30 mil) Launch Pin Ground Conductor .0025 Ground Conductor Launch Pin...

Test Equipment and Techniques An Agilent 8510C network analyzer was used for all of the published measurements. The test port connectors used were 2.4 mm connectors and the frequency range for all measurements was DC to 50 GHz. Calibration was a full 12-term SOLT calibration with sliding loads. The TDR measurements were set up as low pass step in real units. All of the data was taken from the same calibration. Some internal verification of data was done on an Anritsu 37297 network analyzer. Analyzer Workstation (HP 8510C) ► 12-term SOLT calibration. ► Sliding loads were used. ► Single cable...

Explanation of Launch Types Straight Microstrip Straight microstrip refers to a microstrip line straight to the end of the board. The line can be tapered for matching purposes. S21 (dB) Operat or T om as Dat e 02-09-2011 @ 09: 02: 48 M odel num ber: B i l l R QC IR : 8 F i l e nam e 10. dat M eas urem ent s , 1, 2 Not es 8 m i l 4003 board 17 s t rai ght m Top Ground Microstrip Top ground microstrip refers to a microstrip line with a top ground launch structure. The launch geometry is a 50 ohm GCPWG structure. A top ground added to a board can improve microstrip performance and allow for...

An Example of Launch Optimization Original Test Board Design To the right are the results of the original end launch connector test board and a drawing of the board. The VSWR rises slowly through 45 GHz to 1.6:1. When the end launch connectors were first introduced in 2003, a one-inch long GCPWG test board was developed for testing. One of these original test boards was used to establish the baseline performance of the connectors. Test data original 30 mil coplanar test board (Serial Number Ø). Time Domain (TDR) Test Data The TDR data to the right is in real units over time. It shows the...

Simulation Results The plot below is an overlay of the actual test data and the simulated data. The insertion loss has a dip at 45 GHz and the VSWR slowly rises over frequency from below 1.2:1 to 1.6:1 through 45 GHz. The magnitude of the loss is different but the shape is the same. The shape is the most important aspect as it is an indication of bandwidth. This plot shows good correlation of simulated to measured data. The TDR shows the board impedance below 50 ohms and a capacitive dip on either end where the launch pin sits on the board. This also corresponds to measured data. Original...