RF Connector guide RF Connector guide HUBER+SUHNER is certified according to ISO 9001, ISO 14001, ISO/TS 16949 and IRIS. WAIVER HUBER+SUHNER AG It is exclusively in written agreements that we provide our custom- Radio Frequency Division ers with warrants and representations as to the technical specifica- tions and/or the fitness for any particular purpose. The facts and 9100 Herisau/Switzerland figures contained herein are carefully compiled to the best of Tel. +41 (71) 353 41 11 our knowledge, but they are intended for general informational Fax +41 (71) 353 44 44 /11.2008 648116 purposes only. hubersuhner.com HUBER+SUHNER® RF CONNECTOR GUIDE Understanding connector technology Published by HUBER+SUHNER (www.hubersuhner.com) HUBER+SUHNER RF CONNECTOR GUIDE 4th edition, 2007 HUBER+SUHNER® is a registered trademark of HUBER+SUHNER AG Copyright© HUBER+SUHNER AG, 1996 Published in Switzerland by HUBER+SUHNER AG, Switzerland All rights reserved. In particular no part of this publication may be reproduced, stored, or translated, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise without the prior written permis- sion of HUBER+SUHNER AG. Request of reproduction must be addressed to HUBER+SUHNER AG, CEO. Document no. 648116 Printed in Switzerland PREFACE After having been in the RF Interconnection Market for more than fifty years, we felt the need to provide our business associates around the world with a booklet containing key information on coaxial connectors. Today, key concepts behind RF technology have not changed much - and this is what this booklet, the HUBER+SUHNER RF CONNECTOR GUIDE, is all about. It contains HUBER+SUHNER know how and experience in the field of connectors. Primarily, we aim this booklet at non-technically and technically skilled people who are daily confronted with purchasing, distributing or maybe installing RF connectors. The Guide is a reference to coaxial connectors, which embraces the underlying theory, design technology and performance features behind RF connectors. It should enhance the understanding of possible usage, so that people with no or little RF knowledge are able to consider or even select the best suitable connector for their application problem. However, we have to stress that the Guide cannot stand alone as a definite solution to all connector problems. The chapters of this booklet are arranged chronologically, starting with RF theory and ending with electrical measurements. Chapter 1 is a short form of general RF theory, which is partly based on fundamental electrotechni- que. We have tried to simplify the description of the most used RF connector phrases and features, though not omitting the complementary. It is probably difficult to interpret the equations if the reader has no knowledge of electrotechnique. However, the attached explanations are thought to give the non-technical reader the gist of RF behaviour and thereby compensate for the various technical ex- pressions. Chapter 2 contains an abstract of some of the materials used for coaxial connectors. Knowledge of material technology is important as the material influences the flexibility of design and the perfor- mance of the connectors, which applies to both the base materials and the surface finish, i.e. the plating. This chapter is supplemented by the Appendices 5.1 and 5.2, which contain tables with quantities characterising the materials (5.2) and electrochemical potentials (5.1) between them, re- spectively. Chapter 3 is about the design features of connectors and connector series. Every series has a differ- ent design and features that vary. This is important to know because the connector performance has to stand up to the requirements of the application. Additionally, some of the typical applications or market segments in which the connectors are being applied are listed. Chapter 4 is intended to give the reader an impression and practical cognition of the electrical test and measurement techniques for coaxial connectors. As with the theory in Chapter 1, the parameter theory behind the measurement quantities is described to provide the reader with background in- formation. Furthermore, it is valuable input for the understanding of the measurement procedures and eventually of the graphs resulting from the practical tests. The glossary is a summary of common RF expressions. It should help the reader to find explanations to specific terms quickly without having to flip through the whole booklet first. HUBER+SUHNER CONNECTOR GUIDE 3 PREFACE The company portrait is also included in this booklet if further information about our company is desired. Finally, a separate formula booklet is enclosed in the pocket at the back cover of this booklet. It con- tains all equations described in the GUIDE. Among other things, it includes conversion tables to con- vert reflection quantities into, say, return loss. I hope you will find the HUBER+SUHNER RF CONNECTOR GUIDE as useful as we wanted it to be. HUBER+SUHNER AG July 2007 4 HUBER+SUHNER CONNECTOR GUIDE CONTENTS PAGE CHAPTER 1: INTRODUCTION TO BASIC RF THEORY........... 9 CHAPTER 2: MATERIALS................................ 41 CHAPTER 3: RF CONNECTOR DESIGN.................... 59 CHAPTER 4: TESTS AND MEASUREMENTS................ 109 CHAPTER 5: APPENDICES.............................. 136 CHAPTER 6: REFERENCES.............................. 143 CHAPTER 7: INDEX................................... 161 CHAPTER 8: NOTES................................... 165 HUBER+SUHNER CONNECTOR GUIDE 5 RF Theory 1. INTRODUCTION TO BASIC RF THEORY CONTENTS PAGE 1.1 DEFINITION AND GRADUATION OF HIGH FREQUENCY............ 9 1.1.1 Band Designations......................................... 10 1.2 CONSTRUCTION AND FUNCTION OF RF LINES.................. 11 1.2.1 Types of RF Lines........................................... 11 1.2.2 ATypicalRFLine........................................... 12 1.2.3 Electromagnetic Field along a RF Line........................... 12 1.2.4 Resistances and Reactances in a RF Line......................... 15 1.2.5 Impedance of the RF Line.................................... 16 1.2.5.1 Characteristic Impedance of a low-loss Line at High Frequencies........................... 16 1.2.6 Cut-off Frequency.......................................... 18 1.2.7 Wavelength and Frequency.................................. 19 1.2.7.1 Relationship between Frequency and Wavelength........ 20 1.2.8 Velocity of Propagation...................................... 20 1.2.8.1 Influence of Dielectric Material on the Velocity of Propagation............................ 21 1.3 REFLECTIONS.............................................. 22 1.3.1 Reflected Wave (Voltage).................................... 22 1.3.2 Reflection from Various Discontinuities........................... 23 1.3.3 Termsfor Definition of the Mismatch............................. 25 1.3.3.1 Reflection Coefficient Γ ............................25 1.3.3.2 Return Loss RL ....................................26 1.3.3.3 Voltage Standing Wave Ratio VSWR.................. 27 1.3.4 Comparison between Γ,RL and VSWR.......................... 29 1.3.5 Reflection from two or more Discontinuities....................... 30 HUBER+SUHNER CONNECTOR GUIDE 7 INTRODUCTION TO BASIC RF THEORY 1.4 ATTENUATIONLOSSOFRFLINES.............................. 31 1.4.1 Determination of the Attenuation Loss........................... 32 1.4.2 Attenuation Loss Components of Conductor and Dielectric........... 32 1.4.3 Shielding................................................. 33 1.5 THE SKIN EFFECT........................................... 35 1.6 PASSIVE INTERMODULATION (PIM)............................ 36 1.6.1 Specifications............................................. 37 8 HUBER+SUHNER CONNECTOR GUIDE RF Theory 1 INTRODUCTION TO BASIC RF THEORY 1.1 DEFINITION AND GRADUATION OF HIGH FREQUENCY In this first chapter, the main emphasis is laid on explanations to typical parameters in the theory of RF transmis- sion lines, containing coaxial connectors and cables. It should give an impression of how and why transmission lines perform as they do. At the same time, it should provide the reader with fundamental knowledge of common RF techniques including equations, thought as a help or base for the following chapters. In the first section of this chapter, we try to define what high frequency is compared to low frequency and how various frequency ranges are divided. When we look at an equivalent circuit model with a resistive (ohmic) element, the resistance R in a low frequency (LF) circuit will be transformed into capacitive and inductive resistances, C and L respectively, in a high frequency circuit (RF): LF-View RF-View Figure 1 Equivalent LF and RF circuits with ohmic element It is not possible to specify the exact limit between RF and LF. For example, when controlling transistors in the MHz range, LF parameters often have to be used in the calculation, and a LF range can be replaced with an equivalent RF circuit diagram (see Figure 2). LF RF mW 0 kHzMHz 1–3GHz Figure 2 Frequencies divided into ranges from LF to microwaves The limitation in the upper frequency range: RF – techniques Voltages and currents are defined. mW – techniques Usually, only the E-(electric) or H-(magnetic) fields can be indicated (refer to Table 1) HUBER+SUHNER CONNECTOR GUIDE 9 INTRODUCTION TO BASIC RF THEORY High frequency begins where currents and voltages become frequency dependent or where the wavelength becomes important (λ ≃ length of component)