Radio Science for the Amateur

192 Pages·2013·12.758 MB·English

by  Eric Nichols

IIIl
I
IIifiI r
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by Eric Pm NichoBs, KL7AJ
Ham Radio andThe Pursuitof
ScientificExploration andDiscovery
Publishedby
ARRL
100
Contributing Editor: Edith M.Lennon, N2ZRW Proof Readers: Judith Kutzko
Nancy Hallas,WiNCY
Cover Design: Sue Fagan, KB10KW
Technical Illustration: David Pingree, N1NAS
Production: Jodi Moran, KA1JPA Coverphoto:CourtesyofNASA
Shelly Bloom, WB1ENT
Copyright©2013 byTheAmerican Radio
RelayLeague, Inc.
Copyrightsecuredunder thePan-American
Convention
Internationalcopyright secured.
Allrights reserved.Nopartofthiswork may
bereproduced inanyform exceptbywritten
permission ofthepublisher.Allrightsoftrans
lationarereserved.
Printed inthe USA
Quedan reservadostodoslosderechos
ISBN:978-0-87259-338-1
FirstEdition
Table of Contents
UnfinishedBusiness
The Radio Amateurand Scientific Investigation
cnap'ler 1 OnMindset, Measurement, and Making Good Science
Safety First
The Basics
~rJiaIIIE~r 4 Data Acquisition- The Road from Conceptto Confirmation
~l1iaIIIE~r 5 SoftwareToolsfor Hard Numbers
~r1ialn:E~r 6 Optics - WhereRadio Sees the Light
The ElectromagneticSpectrumataGlance
cnap'ler 8 Free Space Radio
~r1iaIIIE~r 9 A PolarExploration, PracticallySpeaking
o
The Big Picture- Plasmaas Pachyderm
1 The ComplexIonosphere-
Weird and Wonderful Non-LinearPhenomena
IonosphericSciencein aCan
Smith Charts, ScatteringParameters, and Sundry ScienceTools
Put SPICEin YourLife for CircuitSimulation
AntennaModelingfrom the NECUp
Large-ScaleDAQand Networking
Graphs and Graphics for aBig Picture
Rolling YourOwn - BuildingInstruments for Radio Science
Now for Some Real Radio Science
TestQuestions and Answers
AlphabeticalFormulary
Foreword
The label "BigScience" most often describes expensive, intricate
projects. But the adjective "big" may also be aptly appliedtoexperiments
distributedover large geographicalareas. Prosaicneeds, like powerand
communications,becomecriticalconcernsfor such experiments. In the
last decade, physicists studyingcosmicrays solved these problemsby
employingpublic schools in the detection ofextended air showers from
high-energyparticleshitting the upperatmosphere. In this book, Eric
Nichols, KL7AJ, astutely observes that AmateurRadio operators may
playasimilarrole for radio detection.
The authorwalks the ham radio enthusiastfrom fundamentals to spe
cifics. The book begins by laying out the elementaryphysicalscienceall
radio amateurs should know to understandthe interactionoftheir equip
ment with terrestrialphenomena. Mr.Nichols brings more than academics
to the task: The messageis clearlyconveyed through the lens ofhis de
cades ofhands-onexperiencein cutting-edgeplasmaphysics laboratories.
Even safety advice is deliveredin the light of some unwelcome events the
authorencountered. Beginners will benefit from the author's experiencein
performing science, in particularfrom his skepticismtoward firstexperi
mental results. Yet,Mr.Nichols also brings afresh approach and sense
ofhumorto the matters athand. For instance, atone point he engagingly
leads readers throughthe details of interpreting aSmith Chart; atanother,
heleaves them admiringhis conversionof astring of Christmas tree lights
into adipole antenna- with avisible standingwave.
The bookthen progressesbeyondfundamentals into how the struc
ture of the ionosphere directly affects radio propagation. The authorspent
decades excitingand probing the ionosphere and knows its behaviorfirst
hand. Even the long-timeAmateurRadio operatorwill benefit from his
detaileddescriptions of the ionosphere's many characteristics that affect
radio transmission and reception.
Armedwith the knowledge and skills impartedby this book, the
AmateurRadio communitymay well contributeto the furtherunderstand
ing ofatmosphere and ionospheredisturbances. Mr. Nichols puts forward
many interestingideas that use the very distributednature of Amateur
Radio operators and their equipmentas aresourcein the continuedexplo
ration ofintriguing ionizationevents. Ilook forward to seeing how this
resource, left underutilizedbyradio science, emerges and perhaps one
day contributes to afirst-rank scientific discovery.
David Saltzberg
ProfessorofPhysics andAstronomy
University ofCalifornia, Los Angeles
April 22, 2012
Preface
Unfinished Business
Part 97.1 oftheFederalCommunicationsCommission's rules and
regulations defines who we are and what wedo asradio amateurs. There
arefiveelements listed in our basis andpurposesection under Part 97.1.
Right after element(a),which addresses our value asemergencycommu
nicators, we find,
s
(b): Continuation andextension oftheamateur proven abilityto
contributeto the advancementofthe radio art.
Somewhereinthe recesses ofmost hams' memories this important
passagelurks, butfewhams have anyidea what to actually do about it.
Wehave been led tobelieve that one needs an advanced degree oracareer
in particlephysics toreally do anything technologicallyinnovative, orthat
the radio arthas been advanced asfar asitcan be advanced. This book,
Radio Scienceforthe Radio Amateur, will neatly demolishthese miscon
ceptions, along with afew others.
Althoughweknow agreat deal about radio inthe 21stcentury, there
is alot we still don'tknow.Most ofthe unexploredfrontiers ofradio have
more to do with the science ofradio than with thetechnology ofradio.
There is animportantdistinctionbetween science and technology, which
isblurredin much literature, andfrankly in most public policy. Science
andtechnology aredifferent but related disciplines. Radio amateurs tend
tobecomeinfatuatedwith the technologyofradio, while neglectingthe
farmore interesting- tomy mind - science ofradio. As wemove into
thebody ofthis volume, wewill discuss more thoroughlythe differences
betweenscience and technology: Itisfartoo importantand subtle to
handle properly inthis short preface.
One ofthe most dynamic fieldsin allof science isthe search for
new,exotic subatomic particles. Traditionally, this has been the domain
of "Big Science" particle accelerators and atom smashers. And, ofcourse,
these large, expensive instruments will always playahuge role infun
damental science. But scientists alsorealize that many ofthese particles
already exist outside the lab, "in the wild," asit were; wejustaren'tin
theright place attheright time to seethem. Backin 2000, Iwasprivi
leged toparticipate with acommunityof scientists who convened atthe
Radio DetectionofHighEnergyParticles firstinternational workshop.
The RADHEPparticipantsproposedmanyfascinating experiments using
widely scatteredarrays ofsimpleradioreceivers ofvarious sorts to detect
theseparticles naturally. Althoughthe RADHEPproposals weredirected
atthe attending scientificcommunity, none of thesereceivers werebe
yond the skill level or resources ofthe averageradio amateur. Modern
dataacquisitionmethods, as well as networkingtechnologies we all now
take for granted, easily allow hams to take partin "BigScience" projects
- the sort ofprojects thatresultin NobelPrizes, by the way.
Regarding the unfinishedbusiness ofscientificinquiry and dataac
quisition, the participants atRADHEP suggestedsomeofthe mostprom
ising avenues ofstudy, in one ofthe mostwidely openfields, for radio
amateurs. One thingradio amateurs have areputationfor is makingreal
ity out of suggestions.
Ihave an impoverishedAmateurRadiofriend who quips, "I have
to eat BottomRamen, becauseI can'taffordTopRamen." Evenduring
the bestoftimes, some ofthe world's premierscientists have taken what
amounts to avow ofpoverty. Basic scienceis ahard sell these days, and
even whenthere's moneyto spare, it'shardenoughto explainto askepti
cal public why we need to send probesto Mars. Duringbad economic
times, it seems thatinterestin basic scienceevaporates, and yet, this is
whereAmateurRadiocan shine.
For manyyears, I workedin ionosphericresearch, both atHIPAS
(HIghPowerAuroral Stimulation) Observatory, now decommissioned,
and atHAARP (HighFrequencyActiveAuroralResearchProgram), both
in interiorAlaska. Thesefacilities are definitelyin the categoryof"Big
Science."The constructionofHAARPwas completedjustafew years
ago with a$200millionbudget. There are only ahandfuloffull-scale
ionospheric facilities on the planet, but for the mostpart, mostnew radio
sciencein recentyears has comefromthem. One ofthe things Ilearned
whileworking at HIPAS and HAARP, however, was thatalot ofthe sci
ence done at these facilities couldbe done by radio amateurs- ifyou
have enoughofthem. Evenmonsterinstallations like HAARPor the
EISCAT (EuropeanIncoherentSCATter) facility in Tromso, Norway,
can only be in one placeat once. Hams are everywhere, and alot ofiono
sphericresearchcan only be donewith widely scattered sensors, which
hams are uniquelyequippedto provide. In Radio Sciencefor theRadio
Amateur,I suggestthat muchofthis researchcan be performedby the
AmateurRadiocommunity- all on aBottomRamen budget- and that
we can contribute significantlytocompletingsome long-unfinishedbusi
ness regarding understandingradio propagation.
I
~01'<__41'-d!J
I'mglad you asked. Radio Sciencefor theRadio Amateurstarts out
with the basic concepts and disciplines of the scientific method, sowe
can all start out on the same page. Whetheryou'venever setfoot in alab
in your life, or you'vebeen experimentingfor decades, Radio Sciencefor
theRadio Amateurwill lead you into some ofthe most fascinating aspects
ofAmateurRadio. Iknow you'll enjoy thejourney.
Eric P.Nichols, KL7AJ
November2012
Acknowledgments
Firstand foremost, Idedicatethis work to God Almighty, Who made
allthings possible, aswell asinteresting. I amhumbledand gratefulthat
He has deignedto share afew ofHis secrets with us mortals.
Iam indebtedto my parents who gave me anengineer'smind, anart
ist's eye, and afully functional set ofcuriosityglands, aswell as astable
environmentin which topursuethem...anincreasinglyrare gift in this
age.
I wish to thankDr.AlfredY.Wong for his vision in creating HIPAS
Observatory, which for 20 years nurturedcountless numbers ofnew sci
entists, and afew old engineers, in the most unlikelyofplaces. While, in
some ways, HIPAS seems like ancienthistory, its contributionto the intel
lectualenvironmentof Alaskaand elsewherewill never be forgotten.
I need toexpress my thanks to anumberof currentand former
UCLAPlasmalab, UCLAPhysics and Astronomy lab, andHIPAS staff
and "hiredguns": RalphWuerker, who taught me everythingIknow
about optics and lasers; Glen Rosenthal, who taughtme how toprogram
inC aswell ashow to setup aplasmachamber; PeterCheung, who gave
me some real interestingengineeringproblems to solve; JackiePau, who
put up with me; Helio Zwi, who taught me the fineartof data acquisition;
Mike McCarrick, who taughtme awhole lot about ionospheric science,
and David Saltzberg, who offeredsome great adviceon this book. Ialso
wish to posthumouslythankDavid SentmanofUAF for his valuable ad
vice and guidance on awide variety of scientific matters.
Last but not least, I am gratefulfor the finestaff members ofARRL,
who for the past 30years have turnedmy chicken scratchesinto works
ofliterature. In this vein, Becky Schoenfeld,WIBXY, and Edith Lennon,
N2ZRW,have conqueredthe most difficult task ofputtingtogetherthis
particularMagnumOpus.
Introduction
The Radio Amateur and
Scientific Investigation
As mentionedin the Preface, one ofthe primaryreasons Amateur
Radio exists, accordingtoFCC part 97.1, isto "...advance the state ofthe
radio art." Many hams would like to take part in this enterprisingaspect of
the hobby, butdon'tknowhow toget started.
The radio amateurisin apositiontoperformmeaningful scientific
investigationin away that is simply not available to many others. As
mentionedearlier, you don'tneed adoctorateinphysics to conductmean
ingful radio science, but you do need toknow some basic scientific tech
niques, commonto every field of science. As aradio amateur, you already
have ahead start.
This is anexcitingtime to be involved in scienceand technology,
perhaps the most exciting inhistory. Ithas been said that there are two
kinds ofpeoplein the world: those who make things happen and those
who sit aroundand wonderwhat happened. By contributingyour radio
skills to pioneeringresearch, you can be abig part ofmaking things
happen.
Most discoveries occurin alaboratory of some kind. Alab may con
sist ofanything, from afew feet ofcounterspace adjacentto asink, to
abehemothlike the two-mile-long StanfordLinearAccelerator(SLAC)
facility inMenloPark, California. Commonlab sciencesincludechemis
try,physics, optics, electronics, biology, physiology, botany, geology, and
computerscience, but there isreally no limit to what can be studiedin the
setting.
There arelaboratories withoutwalls. For many years, I was privi
leged tohave workedin ionosphericresearch, which involved the study
ofthe upperreaches of the atmosphereusing high-poweredradio signals.
Thereare even certaintypes of experimentsbeing proposed(especiallyin
the fieldofparticlephysics) that use the entire Earth as alaboratory.
Despitethe huge variety oflabs, there are certain commonproce
dures, ormethodologies used in allof them. Good scientific methodis
requiredin every type. Ifyou learn and adhere to good scientific method,
you can positionyourselfon the cuttingedge ofradio science and re
search, eitherindividuallyor aspart of abonafideresearchteam. Many
great theoreticians are not great experimenters and must rely heavily on
the insightand practical"chops" of others, includingradio amateurs, to
make their ideas reality. Insightcomes from experience, and experience
comes throughfollowing establishedmethods.
Ifyou thoroughly absorb this book, you will be able to move effort
1esslybetweenthe chemistry lab and the physics lab, orthe electronics
lab and the computerlab, and soon. Youmay even want to start alab of
your own- even ifit'sjustacornerofyour basementshack- to study
something that no one else is studyingyet. In anycase, this bookis for
you.
As aradio amateur, you are probably champing atthe bit to get into
some actual radio science, and you may be wondering why I'mtalking
about all this chemistryand physics stuff. As you'lldiscover, the universe
is astonishingly consistent, and good scientific methodis good scientific
methodregardless of the specific discipline. I, therefore, want to present
acoherent, comprehensivelookat science beforedelvinginto radio spe
cifically.Tothat end, the chapters of this book are organizedto firstoffer
ageneralintroductionto the art and methods of scientific investigation,
followed by afocus on radio scienceand how the radio amateurmight
participatein some importantwork in this intriguing field, and conclud
ing with some specific suggestions to get you startedin conducting solid
science.
Pleaseavoid the temptationto skim over theearly chapters to getto
thejuicy, and perhaps more familiar, radio sections; you mightmiss some
excitingand curious sceneryon your way tothe radio lab.