- - - --- .- . BRL 760 c . lA

REPORT NO. 760

A N I N V E S T I G A T I O N O F S O M E O F T H E E F F E C T S

O F T H E I O N O S P H E R E O N

E L E C T R O M A G N E T I C W A V E P R O P O G A T I O N piCiiA ~f U.S. ~ m x C T T J b3 'ICE 3 - 3 , , i D . 21005

John C. Mester

ABERDEEN PROVING GROUND, MARYLAND

B A L L I S T I C R E S E A R C H L A R ( 1 H A T O R I E S

REPORT NO. 760

July' 1951

AN INVESTIGATIOH OF SOME OF THE EFFECTS OF THE IONOSPHERE ON

ELECTROMAGNETIC 'RAVE PROPOGATION

John C. Mester

Project No. TD3-0538C o f the R e s e a r c h and D e v e 1 o p m e n . t D i v i s i o n , O l r l n a n c e C o r p s

A B E R D E E N P R O V I N G G R O U N D , M A R Y L A N D

INTENTIONALLY LEST BLANK

BALLISTIC RESEARCH LARORATORIES

HlFCRT NO. 760

lrles t e r , l b e Aberdeen Proving Ground, I d . 30 J u l y 1951

A N INVESTIGATION OF SOLIE 0F TIIE EFFECTS OF THE IONOSYFIEHE ON

&ECTROMAGbIE'tIC WAVX PROPOGATION

ABSTRACT

A s tudy is made of t h e m a g n e t o - i o n i c s p l i t t i n g and r e f l e c t i o n of electyo-ilagnetic waves i n c i d e n t obl iquely on a s t r a t i f i e d ionosphere. Certain s lmpl i fy ing assumptions a r e app l i ed t o the theory. Under these sssu~lmtions t h e opinion i s o f fe red t h a t f o r s u f f i c i e n t l y high f requencies t h e l c s g of s i g n a l s t r eng th dua t o s p l i t t i n g and r e f l e c t i o n may be neglected.

REFRACTED RAY

F * x 2

FLECTED RAY INCIDENT RAY

FREE SPACE

W

0 3 k 3 a

FIGURE I

STRATIFIED

2 Q2 IONOSPHERE

sin

i t appear9 advisable, in.viev! of t h e . long ra rge m i s f j l e t o deternine the reduct ion i n signal^ s t r eng th of t h e DOWN' system f o r waves propagated in t h e ionosphere. A t l ong ranges and hence l a r g e angles of incidence, the r e f l e c t i o n , r e f r a c t i o n andmagneto-ionic s p l i t t i n g of waves

p ropaga ted i n t h e ionosphere might poss ib ly cause s u f f i c i e n t l o s s of s ig- n a l s t r eng th as t o e f f e c t the. tracking. d is tance of t h e system. ?sing the magneto-ionic .theory " n the form given by leton( on(^) and o the r s and a s genera l ized by Bookertj) an a t tempt w i l l be made t b determine quant i ta - t i v e l y t o a first approximati.on.the reduction i n . f i e l d s t r eng th clue t o these causes.

MAGNETO-IONIC NAVE SPLITTING

Following Booker, we take a c a r t e s i o n coordinate system (XI, X2, x3)

where X i s a l t i t u d e and consider the ionosphere t o be hor izon ta l ly 3

s t r a t i f i e d , dependent only on X,. (See Figure 1 ) It has been shown (h) J

t h a t under these condi t ions t h e propagation of phase in the . ~ieighborhood of a po in t i n the ionosphere maybe descr ibed by a vec to r (0, s i n 0, q ) where the wave i s inc iden t a t an an l e 0 i n the (2,3) plane. The mag- n i tude of t h i s vector (designated Qe is the index of . r e f r a c t i o n of t h e medium, t h a t is , t h e r a t i o of t h e v e l o c i t y of l i g h t i n f r e e space to. the v e l o c i t y of phase propagation i n the medium. For an ion ized medium Q i s l e s s than one. The hor izon ta l component of t h i s vec to r depends only on the angle of inc iaence afid does no t vary from po in t t o point i n t h e l aye r ; the v e r t i c a l component (q) i s a somewhat complicated funct ion of frequency, angle of incidence, t h e e a r t h ' s magnetic f i e l d and i on densi ty. Booker has shown, under t h e assumption t h a t only f r e e e l e c t r o r i s i n the ionosphere a f f e c t propagation, t h a t q may be expressed by means of a q u a r t i c equation of t h e form

(1) Doppler Veloci ty And Posi t ion: a system f o r determining ve loc i ty and pos i t ion of a m i s s i l e i n f l i g h t by phase .comparison of two radio s i g - n a l s t ransmit ted between two ground s t a t i o n s - one s i g n a l d i r e c t l y , t h e o the r by way of t h e miss i le . 'The inves t iga t ion , however, i s appl icable t o most r ad io p o s i t i o n determination systems. ,. .

'3) Booker; F h i l . 'lrans. Iloy. Soc. Vol. 237 P-hl l (1930)

") Booker; Proc. of Conferencc on Ianospheric Research Vol. 1 (D) ( 1 ~ 4 9 )

It is fur ther assumed tha t darnping by collis ' ion has l i t t i e prac t ica l afi'ect on phase propagation. Inen tile coefficients. in ( l . l j ray b e writ ten a s

where

e , m = charge and mass o f electron i n esu and grams respectively

N = equivalent electron density, number of electrons per cc -9 H = (H1 H2 'Ag) earths magnetic f i e l d iri gauss \-if( = k

"0 = veloci ty of l i g h t i n f ree space (cm/sec)

S = wave Crequency (cps j 'J = angle of incidence, S = s in Q , C = cos Q

q = upward ve r t i ca l component ocphase propagation vector.

The general solution of t h i s equation f o r q gives r i s e t o some d i f f i c u l t y and w i l l in gene a 1 involve c o ~ l e x values of q. However under the trans- 6 formation zi = f a onc can rewrite the coefficients as i'

It can be seen from this t h a t the coeff ic ients of t he odd powers of q are independent of frequency while t he coeff ic ients of t he even powers and the constant term involve the fourth power of the frequency. Hence f o r suf f ic ien t ly high values of frequency the terms in q3 and q m y be neglected and the equation reduces t o a simple quadratic in q.

From t h i s equation it i s then re l . t i ve ly easy t o obtain values of q. This introduces one obvious physical e r r o r i n t h a t it assumes t h a t the e f f ec t of the earth" magnetic f i e l d on the upward and downwad waves i s m e t r i c . However, f o r svf f ic ien t ly high frequencies t h i s asymetrical e f fec t of the earth" f i e l d can f o r a l l p rac t ica l purposes be neglected. The solution of the equation gives r i s e t o two pairs 'of equal but opposite signed r e a l values. We associate the posi t ive values with the up going wave and the negative with the down coming. The l e s se r i n numerical values i s assigned t o the ordinary wave since it i s closer t o the value obtained &enthe magnetic f i e l d i s neglected. One notes t h a t one of the e f f ec t s of the magnetic f i e l d i s t o malce the refract ive indices c loser t o unity.

Perhaps a t this point some reiarlfs should be mile a s t o what i s meant by the ra ther a rb i t r a ry statexileat t h a t one nay use (Eq. 1.2) in place of (Eq. 1.1) f o r suf f ic ien t ly high frequencies. Certainly the obtaining of exact solutions f o r q from Eq. 1.1 is of such difficul-ty a s t o warrant any not too unreasonable simplificzbion. IIo~irever, it i s c lear tha t if one i s chiefly interested i n an investieation of polarization am1 absorption ef fec ts redsilting from a con12lex inclex of refraction, t h a t even a very high frequency does not jus t i fy the use of Eq. 1.2, since Eq. 1.2 in the most par t neglects these effects . On the other hand if the primary con- cern i s with possible t<eu~!<eiling of the signal due t o the inteyaction of two magneto-ionic components of differenl; phase, one needs a high enough

frequency t o malce 77 1 where % is r e d par t of q

qi i s imaginary part of q

t o ju s t i fy the use of I?q. 1.2. The complete mathematical investigation of vhat freauency, f o r a specific value of equivalent electron density

and angle of 'hcidencr , i s necessary t o nwlce q r ( 1 equal any desired -

r a t i o i s beyond the scope of t h i s paper. However, Table I gives some indicaLion of the value of frequency necessary. To s e t up the c r i t e r i a

=o t o be used here one should concentrate on the r a t i o -. n. t h i s r a t i o i s a, >

equal t o o r greater than 10' -then one can f e e l reasonably- sure t ha t

neglecting the terms in q3 an3 q 1611 have l i t t l e e f fec t on the numerical value of q. Hence, f o r frequencies tha t give t h i s value f o r a /a one can

0 3 use Eq. 1.2. Under these conditions the q ' s obtained froin Eq. 1.2 a re essent ia l ly the v e r t i c a l co~nponents of the Q's calculated from the ex- pression given by Appleton

l$, i s the value of the magnetic f i e l d in di rec t ion of propagation

% i s value of f i e l d perpendicular t o d i rec t ion of propagation,

other symbols a s previously used,

present i n the ionized layer, where, f o r up going waves, the posit ive values of q a s calculated from Eq. 1.2 are used t o give t h e ordinary and extraordinary components. One wishes t o consider what e f fec t these com- ponents have upon each other. These two waves, considered a s rays, w i l l talce d i f fe ren t paths and f o r the most part have d i f fe ren t spa t ia l location a t any par t icu lar time. There w i l l exist cross modulation between the waves and fur ther interference due t o difference jn polarization. Study of these e f f ec t s has a t t rac ted considerable a t ten t ion in the recent l i t e r a - turel and w i l l not be considered here. Rather it i s proposed t o make the simplifying assumption, however naive, t h a t the net resul tant f i e l d a t any point i n space near t h e mean path of the waves a t any par t icu lar time, i s merely the sum of two waves of t h e same frequenvj, but of changing phase with respect t o each other. Further, it will be assumed tha t t h i s d i f f e r - ence i n phase i s dependent only on the ve r t i ca l distance of the chosen point from some initial point and the difference in v e r t i c a l refract ive index of the two waves. T h i s l eads t o the consideration t h a t a minimum f i e l d strength due t o interact ion of the two components w i l l occur when the waves are 180" out of phase, t h a t i s when

X2 5 qo) = (2n + 1 ) n + w ( t - s in Q - ;j- %)

0

where n i s an integer.

This reduces t o

with qo, % = the v e r t i c a l indices of refract ion of the ordinary and extra-

ordinary waves respectively, x = ver t ica l distance of point considered 3

above i n i t i a l plane, 3 = wave length.

1. See f o r example 9 Scott, Proc. I.R.E., Vol. (28), No. 9, (1950), P-1057.

Let reference now be made t o Table I1 which gives the q l s calculated from Eq. 1.2 using the coeff ic ients of Table I. Consider only those q ' s t h a t a re ob1;ained when the c r i t e r i a f o r the use of Eq. 1.2 i s sat isf ied; t h a t

a 5' i s 2 5 10 . These values af q are so nearly equal t h a t minimums re- 'a,

3 sul t ing from phase interference rrmst be a r e l a t ive ly la rge v e r t i c a l dis- tance apart. Hence, it seems reasonable, considering a l l the a s m p t i o n s made and real iz ing t h a t the values of the q's a r e probably accurate only t o three f igures and cer tainly not more than four t h a t one can, f o r frequencies sat isfying the c r i t e r i a on the use of Eq. 1.2, ignore these minimums and considered the two components a s one wave of the same fre- quency and phase. ,

REFLECTED AND REFRACTED COPIFQNEbiTS OF THE WAVE

It i s now wished t o study the e f f ec t of re f lec t ion on the wave. Treating a p l ~ s p o l a r i z e d wave incident on a s t r a t i f i e d ionized medium an attempt w i l l he made t o determine the re f lec t ion and refract ion r a t i o s i n t e rns of the index of refraction and the initial angle of incidence. Consider f o r the moment, only a single layer of the ionosphere with t o t a l re f rac t ive index Q and assume a plane polarized wave incident on the layer a t an angle 8. Part of the wave w i l l be transmitted t h m the medium and the remainder wi l l be reflected from the layer. Assme t h a t the re f lec t ion talces place a t tho boundary of the layer.

One m y take the angle of incidence t o be in the 2-3 plane a s before without l o s s of generali ty and one may further assume t h a t the mgnetic vector H of the wave i s in the plane of incidence and the e l e c t r i c vector E n o d t o it. Let IH, IE be the incident magnetic and e l e c t r i c vectors

respectively; RH, RE the reflected vectors and DH, DE the refracted -- - -

vectors. The usual boundary conditions t h a t tit the ref lect ing surface the tangential components of E and H must be continuous hold, t h a t is,

where t refers t o tangential -component.

Since E i s normal t o the plane of incidence, it will be tangent t o the boundary so one can write 2.1 a s

If one takes a s the angle of refract ion and takes t he angle of r e f l ec t i cn a s equal t o the angle of incidence one can wri te

(2.4) IH = IH cos 8, qlt = % cos €2, DH = DII cos @ t t

Furthermore, f o r a plane wave 1 H = E h:~ere 1 i s the i n t r i n s i c impdance of the medium. Eq. (2.2) can then be wri t ten a s

IE cos Q - RE cos Q DE cos Q (2,s) d -

10 7 0 1 1 ' The mi.nus sign a r i s ing from the f a c t t h a t E and H a r e of opposite sign a f t e r reflection. Combining 2.3 and 2.4 one obtains

RE "1 10s Q - y cos pI 5 = 7 C O S 0 + 7 COB $f

D~ 2 y l c o s Q ( 2 7 ) 5 = Y , 1 C 0 3 0 +

0 "OS P' and. in a s imilar manner

RH CO" Q - g o cos PI (2.8) = -

9 1 cos Q + t l cos @

D~ 2 1 0 cos Q (2.9) q" yl cor Q + yo cos @

N e 2 If one now s e t s 7 = (&)lh' ,here E~ = 6 ( 1 - )

k 2 6 m '

& = d i e l e c t r i c constant 4 = per-rfieabiliLy, t he other symbols a s before, one nlay wri te

M 0 112 (2.10) = (-1 f o r f r ee space

0 C' y 1 112

= (-) f o r i o n i z d medium 6 1

The permeability of the ionosphere i s very.nearly equal t o t h a t of f r e e space, hence

And f o r a low conducting medium one has

So t h a t

(2.13) Qe where Q $s the t o t a l re f rac t ive index of ? 1

the medium.

By Sne l l l s law one can wr i te sine where Qo = 1, hence xiv=x 2 1/2

( 2 . 4 ) cos $ = (e2 - sin 8 )

' Substi tuting these r e l a t ions in 2.6 - 2.9 it follows t h a t

RE Qo COS go - Ql cos q cos go - q1 (2.15) - = IE Qo cos 8 + Ql cos

0 r+.-CoSQ 0 + q 1

= Y 2 cos eo 2 cos 'a0 - - (226) 5 = Qo cos % + Ql cos 8, con 8 + ql

0

Qo C O S eo - % COS 0 1 "0" so - 91) = - (% cos Q0 + Q1 con Q1 = - (cOs8 + ql

0

DH 2 q c o s Q 0 2 Q1 cos 8 t

0

(2.18) 5- Qo cos €I + 4 cos 9 cos go + ql 1

One may note tha t these r a t i o s are functions of the angle of incidence and the index of refract ion h i c h i t s e l f i s a function of N, f and the magnetic f i e ld .

It i s wished now t o ex-tend this development t o a s t r a t i f i e d ionosphele. Let there be (n) layers numbered consecutively (1, 2 - - n); t o each layer assign a Qi ( i = 1 - - - n). For f r e e space assign Qo = 1 and l e t h, be

0 I

the wave incident on the boundary between f r e e space and t he first layer a t .angle 8 Then RE and D trill be the ref lected and refracted waves

0. Eo 0

respectively associated with the incident wave , RE-, and DE wil l -be 0 J , j

ref lected a d refracted waves associ,ated with I the incident wave on Ej' . .

the boundarg between the j and j + 1 laye r . . Neglec.ting absorption through '

. .

12

the layer DE = I The equations can then be wr i t ten in t he j E j + l

following form

where. 2 cos 8,

M = 0 8, cosQo + Q1 cos q

2 Ql cos Ql

= Ql cos q + Q2 cos Q 2

2 cos Q (2.20) M = n n & cos Q + Qml cos 8n+l n

NOW Sin Qo (2.21) Sin Q~ = ( R ~ - sin' go) sJz

% , "OS =

from which

(2022) = - - 2 2 2 '? = %

(4: - Sin ~ ~ 1 ~ ' + ( Q ~ ~ - s i n %lYL % + r-~i +L

I n -a similar inamlor

cos Q - Q1 cos Q K = 0 1

o cos Qo + Q1 cos Q 1

o r 2 1/2 ( 4 2 - s i n 2 . )1/2- (g2 -sin (2.25) Kn 3

0 nc l 3

2 ( s 2 - sin Q ~ ) ~ ' ~ + ( Q ~ ~ ~ - Sin go) lI2 %+%l

Final ly one has f o r t h e r a t i o of the reflected and refracted nave a t the'

nth Layer boundary t o the incident wave i n f r ee space.

The e n e r a in the transmitted \rave is dependent on the index of refract ion 'nd the area of the ray, If one l e t s I[ be the energy i n the incident

3

wave and D be t h e energy i n the refracted %rave, one can write Eo

2 2 D~

0 cos Q D~

0

0 q1 - (q-1 (,,, g 'Ql cos Q

60 0 0 0

I n a similay n m e r if RE is the energy i n t h e ref lected wave then

R E n (2.29) p= (2)

IE cos Qo €0 0

It i s now possible t o apply the equations derived t o cer ta in iclea.liaed, b~rL rcL2resentc:tive cond'ltions. Let there first be s e t up a s t r a t i f i e d ionosphere of four layers and l e t the equivalent electron

6 G 6 density i n the layers one t o four be .1 x 10 , .2 x 10 , .5 x 10 and G 1 x 10 elec-Li-ons per cubic contj.mneters respectively. Then a wave of

frecl_uency f ~1x1. incident a t i!n&le Q on layer one w i l l be pa r t i a l ly transmitted and p?.r-tially reflected. The enersy t ransni t ted i n t h e four-th layer f o r freq~tencies of 110 me. and 100 mc. incident a t 30' and LOo respectively r>rill be calculated,

From Table I1 t he q l s correq?onciing t o cn o r d i n a ~ j >wave of 110 mc and 30° angle of incidence ore

ql = .8630 q, = ,.8509

q2 = .8600 = -0356

then frat1 Eq. (2.25)

The t o t a l reflec.Led energy w i l l be the mr,~ of 'the energy reflec.ted from each bound:lry of the medium. That i s

3

From Q. (2.29) t h i s my be wri-tten a s

Then the energy translnitted t o the foui-th l aye r (since absorption i s being neglected) i s merely

O r the energy transmitted can be found d i rec t ly from Eq. (2-28)

Th i s agreement between the transmitted energy i s s e l l within the accuracy of the f igu res used. Furthermore it appears t h a t one can f o r prac t ica l purposes assume tha t all the energy i s t ranmit ted.

I n a sinlilar manner f o r f - 100 mc, Q = 45"$ from Table II we deter- mine the energy transmitted t o the Lth layer.

K = ,7071 - ,7065 .EQ6 o .7071 + ,7065 =1- loU2 - 1.m& M o = n m i -

.7m5 - .70& - .m5 1*U30 - l.m~ !L = .TO65 + .TO60 - %=m!iz-

.7960 - .70&2 -0018 K2 .TO60 + -7042 114102 = 1,0013

M2 = ixiz ,7042 - -7013 - -0329 1'4004 - le0320

K3 a .TO42 + .7013 - 1.4056 M 3 = i m % 5 ' -

The enerpj transmitted t o the fourth layer will then be

CONCLUSIONS

A s was previously stated, absorption i n the ionized medium has been neglected. I-Iowever, t he energy l o s t by absorption i s approximately inversely proportional t o the square of the frequency. IIence, fo r the frequencies under consideration, t h i s l o s s +rill be m a l l and. can, f o r most p rac t ica l purposes, be ignored. This has f o r the most park been born out by pre- vious experience. The net r e su l t of t he investigation then i s t h a t f o r suff ic ient ly high frequencies, and f o r angles of incidence not exceeding 40" t o a'', the l o s s of s Q n a l strength due t o magneto- io~c sp l i t t i ng and

i ti

to ref lect ion from the ionosphere i s of a negl igible nature. : .

I . . 2 coefficients of ( q l s ) in a ! $ + a q3 + a2 q + al q + a. = 0 Ir 3

Determined Values of q

Imaginary

Imaginary

No. of Copies -

DISTRIBUTION LIST

6 Chief of Ordnance Washington 25, D. C. Attn: ORDTD - Bal Sec

'10 B r i t i s h - OPDTB f o r d i s t r ibu - t ion

O f i n t e r e s t t o : D r . K. Weclces Ca~nbriclge Univ.

D r . J. A. R a t c l i f f e Cavendish Lab,

D r . J. 1J. COX Defense Research Doard 0 bt;nm, Canada

D r . D. d o Curr ie Univ. of Saslrat che~ran

D r . William T i l s t o n Univ. of Toronto

7 1 P a r t s C and DG of AIUP/GM L i s t No. 15

4 Chief, Bureau of Ordnance Department of t h e ifavy Washington 25, D. C. A-ttn: Re3

2 Chici' of I\IavLiL Research Departmen-t of t h e I'Iavy Washington 25, D. C. Attn: S c i e n t i f i c Li-tera-

t u r e Branch (N482)

2 Commander Naval Ordnance Laboratory I f l ~ i t e Oalc S i l v e r Spring 19, Mac!. Attn: The Library, Rn 1-333

1 C o m n d e r Naval Ordnance Tes t S t a t i o n Inyokern P.O. China Lalre, Cal if o n l i a Attn: Technical Library a d

E d i t o r i a l Sec t ion

1 Supei-intendent Postgraduate School U. S. ?Java1 Academy Amapol is , Ih r j l a i ld

1 Cofi~nandln~ G e n e r d A i r Univers i ty l ' k - a~e l l A i r Force Base 14ont~onery, Alabama A t t r , ; A i r Un5.versity Library

2 Cocunanding Genoral A i r F h t e r i e l Comnand Wright-Pa'tterson A i r Force Base Dayton, Ohio Attn: GIDO-D

1 National Gureau of S t a i l d a d s Trlashingion 25, D. C. A-ktn: M r . '1. H. Shapley

1 Cen t ra l h d i o Propagation Lab. National h r e a u o r Standamis Wa:;hingi;on 2 5 , D. C. -

1 Corrllilanding O f f i c e r Attn: D r . J. H. De l l inge r Naval Proving Ground Dahlgren, V l rg in i a 1 Office, Chief S igna l Of f i ce r

1i~sl1ington 25, D. C. 1 Co~ru;~mding O f f i c e r 'A-ttn: fir.. A.R. Beach

bIa-iral Aviat ion Ordnance TesL S L ~ t i o i l 1 Naval Research Laboratory

Chincoteaeue, V i rg in i a Washb~lgton 25, D. C , At-tfi: D r . T. R. Ek~rnight

No. of Copies

No. of Co oie s -

1 Signal Corps mgineering 1 Lab.

Fort Monmouth, J J. At-Ln: Mr. 11. Blake

1 Pasadena Physics Section USNOTS 1030 Green S t r ee t Pasadena, Calif orilia kktn: D r . David R. Bates

1 1 University of Alaska

College, Alaslca Attnr D r . S. L. Seaton

1 Canlegie In s t . o f Washington.

Washington 25, D. C. Attn: D r . L. V. Berlmer

1 1 Ionosphere Research Lab.

Penn S ta t e College S ta t e College, Pa. Attn; D r . John M. ICelso

THRU : Cormding O f f i c c r Pittsburgh O r d . D i s t r i c t 311 Old P.O. Building 1 kLh Ave., and Smithfield

S t r ee t Pittsburgh 19, Pa.

1 California Inst . of Tech. Pasadena, California Attn: D r . Sidney Chapnlan

THRU: D i s t r i c t Chief 1 Los Angeles Ordnance D i s t . 35 North Raymond Ave. Pasaclcna 1, C a l i f o r ~ a

LIST

Co me11 University Ithaca, blew Yorlc Attn: D r . H. G. Booker

THlIU: D i s t r i c t Chief New York Ordnance D i s t r i c t 180 Varicl: Street, Nmi York a, New. Yorlc

Wxtson Laboratories R e d Bailk, New Jersey Attn: M r . Ralph I. Cole

Raytheon bnufa.,c-i;uring Go. Waliliam, T.bssach~~sett s Attn: D r . J. T. deDettencourt

TIFLU: 1,ispector of Navd Material 495 hunmer Strcet Boston 10, 1.lassachusetts

Ncri Yorl: University Nev York, New York Attn: D r . Bernard Fricdman

THRU : D i s t r i c t Chief New Yorl: Ordnance D i s t r i c t 180 Varicl: 5tree.t Iiew YorIc d, New Yoi-k

Geophysical Research Directorate Cambridge, Phssachuseits Attn: M r . N. C. Gerson

TIIRU : D i s t r i c t Chief Boston Ordnance D i s t r i c t Boston Arqy Supply Base Boston 10, Phssachusetts

No. of Copies

DISTRIBUTION LIST

No. of Copies

1 Univ. of CaliCornia 1 Dell Telephone Laborxtories Lo s Angeles, California New Yorlc, New Yorlc Attn: D r . W. W. ICellogg Attn: Dr. S. A. ScheUcunoff

T E N : TI,RU : D i s t r i c t Chiof Chief, NQW York AFPFO Los Angelas Orclnance Di s t r i c t 67 Broad St ree t Pasadena 1, California N e w York 4, New Yorlc

1 Johns Hopltins University 1 Glenn L. Martin Company Baltimore, Phrylanxl Baltimore 3, Maryland dttn: D r . D. E. ICerr Attn: D r . Harold Schutz

T E N : T I N : Naval inspector of Ordnailce Bureau of Aeronautics Applied Physics Laboratory Kepresentxtives Johns FIopl6ns ITniversity Glenn L, Phrtin Conipany 0621 Georgia Avenue Baltimore 3, Pkrylancl S i lver Spl-illg, p h n ~ l a n d

1 Stanford University Stanford, California Attn: D r , L. A. h i m i n e

THRU: D i s t r i c t Chief San Frailcisco OnJ. D i s t . Oakland Army Base Oaldanrl 14, California

l Cruft Laboratory Hamard University Ccmbrid.ge, ?rmssachu s e t t s Attn: D r . H. R.' Fi.iiiimo

TI-RU: D i s t r i c t Chief Boston Ordnnilce Di s t r i c t Boston Aqy Supply Base Doston 10, Ixkssachusetts

1 RCA Laboratories Div. Neri Yorl:, ??em York Attn: D r . A. B. 140ulton

TIBU: Chief, Mew Yoyl: UPFO 67 Broad St ree t Nerr York 4, New York