Microwave Know How for the Radio Amateur - n5dux.com PDF
Preview Microwave Know How for the Radio Amateur - n5dux.com
.. # J ; • - Microwave Know How for the Radio Amateur Edited by Andy Barter, G8ATD , ~-,." .,, & mRSGB Radio Society of Great Britain Published by The Radio Society of Great Britain, 3 Abbey Court, Fraser Road, Priory Business Park,Bedford,MK44 3WH. First published 2010 © Radio Society of Great Britain, 2010. All rights reserved. No parts of this publication may bereproduced, stored inaretrieval system, ortransmitted,inany form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the Radio Society of Great Britain. ISBN:9781905086563 Publisher's note The opinions expressed inthis book arethose ofthe authors and not necessarily those of the RSGB. While the information presented is believed to be correct, the authors, the publisher and their agents cannot accept responsibility for the consequences arising for any inaccuracies or omissions. Cover design: Kim Meyern Production:Mark Allgar, M1MPA Typography: Andy Barter, KM Publications, Luton Cover photograph kindly supplied byVHF Communications Magazine Printed inGreat Britain by Page Bros of Norwich Acknowledgements The articles in this book have been supplied by radio amateurs from around the world. The editorwould like tothank the following people and organisations fortheircontributions: Ralph Berres, DF6WU Kent Britain,2EOVAA/WA5VJB JOhn Fielding,ZS5JF JoseGeraldoChiquito Dom Dehays,F6DRO Stephen Hayman,ZLHPH Sam Jewell,G4DDK EdJohnson,AD5MQ Michael Kohla,DL1YMK Gunthard Kraus,DG8GB Alexander Meier,DG6RBP Roger Ray,G8CUB Franco Rota, 12FHW MatjazVidmar, S53MV Paul Wade, W1GHZ Henning CWeddig, DK5LV DrJohnWorsnop, G4BAO RadCom UKW Berichte Magazine VHFCommunications Magazine Scatterpoint,the magazine of the UK MicrowaveGroup VHF Communications Magazine • Constructional and theoretical articles on all aspects of VHF, UHF and Microwaves • Published in English since 1969 • Available by annual subscription • Kits and PCBs available for most constructional articles Web site www.vhfcomm.co.uk • Subscribe on line • List of overseas agents • Downloads of some past articles • Search or download a full index of the magazine since 1969 • Links to other interesting sites Back Issues • All back issue available as real magazines CommunicationsMagazine or photocipies Adecadeof The magazines • Back issues on DVD, a whole decade of magazines on each DVD • Binders to hold 12 issues (3 years of magazine) K M Publications 63 Ringwood Road, Luton, Beds, LU2 7GB, UK "feIlFax: +44 (0) 1582 581051 email: [email protected] Contents Chapter Title Page 1 Antennas 1 •Weatherproofmicrowave antennas •6cm antenna •Vivaldi antennas 2 PowerAmplifiers 47 • 1W power amplifier for 9- 11GHz •23cm amplifier 3 Measuring Equipment 59 • Improving Harmonic response of the HP8555A • 1OMHz- 10GHz noise source • Noisefactor measurement with older spectrum 4 Filters and Design 97 • Interdigitalcapacitors • Bandpass filter for microwaves • Hybridcoupler 5 Modifying Commercial Equipment 127 • Eyal Gal 21.2 - 23.6GHztranceiverfor24GHz •Converting the Cenager7HGz modulefor 5.7GHz • DXR 700 conversion to 5.7GHz • Using EyalGal 11GHz transverteron 10GHz •24GHz White Boxes 6 Converters 143 •S Band Receive Converter (uses aYIG LO) • 144MHz DownConverter 7 Oscillators 161 • DDS using the AD9951 oscill~tor • MMIC experiments Index 177 Preface Ithas beenfive yearssince Iedited Microwave Project2.Since thenthe devices and equipment available to amateurs interested inthe microwave bands has continued to increase.This book contains some of the things that are being used right now and some the surplus equipment that has come onto the market that can be modified for use onthe microwave bands. The articles on surplus equipment have been taken from Scatterpoint,the magazine of the UK Microwave Group, this is a very active group an I recommend that any amateurs in the UK shouldget along toone ofthemeetingthat are held aroundthe country to see how useful being part of this group can be to get the most out of the microwave bands.There are similar groups in many othercountries that Ian surewould bejust as helpful if you do not live inthe UK. So that readers will not think this isjust a face-lifted version of the earlier Microwave Projects books it has beendecided to give this book a new more descriptive title. Many of the articles require a PCB, the artwork inthis book is not reproduced to exact size,so if you are going to make you own PCBs please take care to scale the artwork correctly. I recommend that you take an easieroption because most of the authors cansupply PCBs and I have included contact detailswhere possible. Many ofthe contacts areemail addresses orweb sites, unfortunately these have a habit of changing, they were current at the time of editing (January2010). Ifyou havedifficultieswith PCBs,finding components orcontact details please contact me and Iwilltryto help. Andy Barter,G8ATD, Email:[email protected] Chapter Antennas In this chapter: • Vivaldi antennas • Weatherproofmicrowave antennas I • 6cm antenna ntennas are one of the features of a microwave station that differentiate it from other frequencies. We areluckythat incredible gaincan beachieved andthey can beplaced at many wavelengths above the ground with ease. Something that makes amateurs operating on other bands very envious. \ Weatherproof antennas for UHF and lower microwave frequencies [1] Radio amateurs,weather effects and antennadesign Quite frequently, radio amateur antenna design is limited to a few popular antenna types. Directionalantenna designs are usually limited to Yagiantennas for the lower frequencies and parabolicdishes for the microwave frequency bands. The operation of aYagi antenna is based on a collimating lens made of artificial dielectric like rods, loops, disks or helices. The basic designgoal ofallthese slow-wave structures istoachieve the maximumantenna directivitywith the minimum amount of material(metal). ' The situation isactually madeworse with the availabilityofinexpensiveantenna simulationtools for home computers. The latter provide designs with fantastic gain figures using little hardware. Unfortunately, these results are barely useful in practice. Besides impedance matching problems, such designs are extremely sensitiveto manufacturingtolerances and environmental conditions: reflections from nearby objects and accumulation of dirt or raindropsonthe antenna structure. The operation of a 2m (144MHz) Yagi with thin rods (or loops or helix) antenna will be completely disrupted if snow or ice accumulates on the antenna structure. Raindrops accumulated on theantenna structure will completely compromise the operation of a 23cm (1.3GHz) or 13cm (2.3GHz) Yagi antenna. Manufacturing tolerances limit practical Yagi antennas to frequencies below about 5GHz. Professional VHF Yagiantennas use very thick rods to limit the effects of snow and ice on the antenna performance. All professional Yagi antennas above 300MHz are completely enclosed inside radomes made of insulating material that is transparent to radio waves. Since any radome includes some dielectric and the latter has a considerable effect on any Yagi antenna, aYagi antenna hasto becompletely redesigned foroperation inside aweatherproofenclosure. Ifsome natural dielectric (radome) isadded,then some artificialdielectric (Yagi rods) has to be removed to maintainthe same focal lengthofthe dielectric collimating lens. • Simply speaking, any serious design of a weatherproof Yagi antenna for frequencies above 300MHz is out-of-reach for most amateurs. Fortunately there exist other antenna solutions for
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