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M. Singh et al.
2 Design of Single Antenna Element for Terahertz
Applications
2.1 Design of Proposed Single Antenna Element
To develop the proposed terahertz planar antenna, a polyimide substrate material
having a dielectric constant of 3.5 and height 50 μm is used. The copper with thickness of 2.1 μm is chosen as the conducting material. The dimension of rectangular
patch is computed by using the equations below [29]. Here the length and width of
the rectangular patch are calculated by using Eqs. (1–2)
P l =
(2N + 1)
√
ε eff
×
λ
2
− L
(1)
P w =
(2N + 1)
ε r +1
2
×
λ
2
(2)
where N is an integer, effective, and relative dielectric constants are given by ε eff and
ε r, respectively. Also, the following expression may be used to measure the upper
limit of substrate thickness h to mitigate the surface wave effect in the printed circuit
board.
h =
λ
4
√ ε r
And the effective dielectric constant has been computed by using equation a
ε reff =
ε r + 1
2
+
ε r − 1
2
1 + 12
h
P w
−1/2
(3)
And here due to fringing effect, the increase in length is given by using the
following equation
L = 0.412h
(ε reff + 0.3)
P w
h
+ 0.264
(ε reff − 0.258)
P w
h
+ 0.8
(4)
The length (L f ) and width (F w ) of 50 transmission feed line is calculated by
[30]
F w =
1
0.8
9.5138h
e
√ λ(ε eff + 1.41)/Pw
− t
(5)
L f = (2M + 1) × λ/2
( 6 )