Appendix
Offset selection
Free space wave length
Guide wave length
Surface reactance
Reactance-45
Transmission Loss
Return Loss
Slot field
Voltage ratio
Theoratical radiation pattern
of circular aperature main lobe
Aper ture field
Elliptic loop antenna
Radiation pattern of elliptic
aper ture
178
181
182
183
184
185
186
187
188
189
190
191
192
t
Offset selection
The attenuation presented by a hallow reactangular
guide
depends
on
the
wavelehgth,proximity
relative magnitudes of
illustrated
by
the
a
and
graphs
b.
The
shown
to
various
in
the
metal
cutoff,and
effects
fig.ap
are
1.1
The
attenuation are calculated from the re 1 ationsC441-From the fig
ap 1.1 it is clear that for the most favourable attenuation low
ratios of b to a should be avoided.In
waveguide
may
of
not
be
fesible
to
make
use
practice
these
it
favourable
proporations.In the most of the guide design ,the dimension
to be less than X/2.
and
a
to
be
less
than
X.This
naturally b/a = 0.5.In present case b/a > 0.5 which
slight ' higher
attenuation.The
dimension
b
leads
indicates
selected
for
the
waveguide takes account of higher order waves,and unfavourable
states of polarization.
withftview to studying the effect of dimension
radiation
characteristics
with
increased
'b'on
slot
attenuation
some
offset values are selected.
It was reported that a cs slot at offset a/4 at an
angle
+ 45 radiates circularly polarized wave!19,20].
If we consider the ratio b/a of
the
guide
then
offset
value of circular polarization = a/4 = b/2 when b/a = 0.5
In
actual
practice
b/a
>
0.5
by
small
amount.Such
selected dimension of the waveguide has some error value,
i.e.
error value=ideal value of b- actual value of b*=0.25mm
Hence this value is added
to
each
selected
offset
study the effect of attenuation on cs antenna element at
178
to
some
!
?
&iEmuOfCY J-A/
*f£&fi£Yci-ES
Fig. ap 1.1.
179
P€A SECOND.
offsets assuming b/a - 0.5.
actual offset + error value = selected offset
In case of loading (corrugation
ness of the bar is measured.Half
and
of
loading),the
fin
this
value
thick
along
with
error is used in fixing the offsetC431.
The above empirical relation seems to agree with the some
of the offset calculations by Sangster [20,211.
From all observations carriedout in the experiment it
possible to conclude that the attenuation is uncritical
is
which
is maximum at the centre or along the guide axis ,decreases to
minimum in the intermediate region ,and
edges.
180
again
increases
at
program freespacewavelength;
const
c=3.0 ;
var
f,lam:real;
begin
write('enter the value of f');
read(f);
lam:=(100*c/f);
writeln<'lam= ',lam:2:2);
end.
181
program guidewave1ength;
const lame=46.00;
var
lamg,lam:real;
begin
writeln('enter the value of lam');
read(lam);
lamg:=lam*lamc/sqrt(lame*lame-lam*lam)
writeln('lamg=
*,lamg:2:2);
end.
182
program surfacereactance(input,output);
const
pi=3.142;
var
d:real;
a,b:real;
Nr,Dr,Cr:real;
lamzreal;
begin
writeIn(‘enter the value of d,
readln(d,a,b,lam);
Nr:=sin <2*pi*d/lam)*a/b;
Dr: =cos <2*pi*d/la«n)*a/b;
Cr:=—377*(Nr/Dr);
writeln('Cr=
end.
183
',Cr:2:2>5
a, b * 1 am'
Program Reactance_45;
const
pi
=3.142;
lambda = 2B.57
;
a = 23.00
;
beta=0.001953;
k=0.009118;
var
xi, eta, thetarreal;
Itheta, Jtheta
: real;
xl,
N, M : real;
N1,N2,M1,M2:real;
N3,M3,ll,12:real;
begin
c1rscr;
write('Enter theta <45> : ');
readln(theta);
theta := theta*pi/180;
writeln(sin(theta):6:5,'':5,cos(theta):6:5)§
write('enter xl');
readln(x1);
xi := lambda*beta / (2*pi) * cos(theta)
- lambda / (2*a) * sin(theta);
eta := lambda*beta / (2*pi) * cos(theta)
+ lambda / (2*a) * sin(theta);
writeln('xi =
' ,xi:6:3,'':5,'eta = *,eta:6:3);
Itheta := cos(pi*xi/2) / (l-xi*xi)
+ cos(pi*eta/2) / (l-eta*eta);
Jtheta := cos(pi*xi/2) / (l-xi*xi)
- cos(pi*eta/2) / (l-eta*eta);
writeln('Itheta = ',Itheta:6:3,'':5,
'Jtheta = ',Jtheta:6:3);
N ;=(( Itheta * sin(theta) + pi/(a*beta) *
Jtheta * cos(theta) ) * cos(pi*x1/a)>
M := ((Jtheta * sin(theta) - pi/(a*beta) *
Itheta * cos(theta) ) * sin(pi*xl/a));
writeln('N
writeln;
= ',N:6:3,'':5,'M =
end.
184
',M:6:3);
;
program transmission(input,output);
const
k=0.1869;
var
N1,N2,M1,M2,A:real;
sqrNl,sqrN2,sqrMlfsqrH2:real;
Begin
clrscr;
writeln('enter the value of N1,N2,M1,M2');
readIn(N1,N2,M1,M2>;
A:=(-k)*(sqrNl+sqrMl)/(1+k*(sqrNl+sqrMl>)+
(-k)*(sqrN2+sqrM2)/<1+k*(sqrN2+sqrM2));
writeln('A= ',A);
end.
185
program ret loss
const
k0=0.0483784;
a=22„0;
b=l1.0;
e0=1.0;
w=2.0;
beta=0.029708;
var
n,c,b01,altm,b02,b03,b04:real;
begin
write('enter the value of al');
readln(al) ;
c:=1/120*k0*a*a*b*al;
write('c=
',c:2:2);
write!'enter the value of n and m
readln(n , m);
bOl:=-e0*w*c*n;
b02:=m*e0*w*c;
b03:=eO*w*c*n;
b04:=m*e0*w*c;
end.
186
program slotfield;
const e=1.0;
r=l.0;
1=1.0;
pi=3.142;
c = l;
var theta:real;
k, kl,f:real;
begin
write('enter the value of theta');
readln (theta);
f:=(pi*theta)/180 ;
k:=e*cos(f)/2*3.142*e;
kl:=k*(l/c*r*r+(c/r*r*r*2*pi*10.5*10E+9)*l/cos(f)*cos(f))
write('kl= ‘,kl:2:2);
end.
187
If
M
W
-S
i
1
W■Pi
it-
program voltratio;
const lam=28.54;
pi=3.142;
b=l1.5;
a=23.0 ;
lamg=42.0;
w=2.0;
var
V,g,e:real;
begin
writeln('enter the value of g');
read In (g ) ;
v: =sqrt(12.74*2*pi/1am*2*pi/1amg*b*g/a)
write('v= ',v:2;3);
read (v );
e:=v/w;
write('e= *,e:2:4);
end.
188
TKeoratical radiation pattern
apera.tu.r-a main Jobe only
189
circular
program apperture;
const lam=2.8;
pi=3.142;
var a:re a1;
c,k,f,theta:real;
begin writeIn('enter the value of a');
readln(a);
c:=2*pi*a/lam;
write('c= ',c);
writeIn('enter the value of theta'
readln(theta);
f:=pi*theta/180;
writeln('f= ',f);
readln < f ,c );
k:=1/3*sin(f)*c ;
write('k= ',k:2:2);
end.
190
program loopantenna;
const
pi=3.142;
lam=28.3;
var
clam,j1,f,k,a:real;
^
theta:real;
begin
writeln('enter the value of theta');
readln(theta);
f:=pi*theta/180;
k:=sin (f);
writeln('enter the value of a');
readln(a);
clam:=2*pi*a/lam;
write(*k= ',k,'clam= ',clam);
read(k,clam);
j1:=k*clam;
write(*jl= ' , jl) ;
end.
191
Ra.Jia.tion
p a ttern ,
of
e llip tic
192