6 Dipoles Log-Periodic Antenna
6 Dipoles Log-Periodic Antenna
6 Dipoles Log-Periodic Antenna
AbstractThis paper shows the design of the 6 dipoles logperiodic antenna , and essential features coupled to a waveguide,
with some working frequencies between 1,8 and 7 GHz, and
source with coaxial cable power via.
I. I NTRODUCTION
Lm
Lm +1
Sm
Sm +1
Wm
Wm +1
Where:
m : element length m
Wm :element width
Sm :is the separation between the element m and the m+1
A. Larger dipole design
The final length of the dipole depends on the characteristics
of the substrate, specially dielectric constant, in this case we
used a specific substrate for high-frequency, it is baquelite,
whose characteristics are: h=1.2mm and a dielectric of Er=4.8
finds.[4]
B. Separation between dipoles
After obtaining the necessary number of dipoles and the
length of each of them, need to know the distance between
the two largest components of the distribution. The remaining
gaps between dipoles will be related by the selected scale
factor, except l smallest separation between the dipole and the
feed point.[4]
Sm =
1
2
(Lm Lm 1 ) cotg()
1
2
( 02n
0 n1
)
2
cotg()
cotg() = 4 1
D. Results
Now, other graphic obtained with Designer is about the
parameter S, in the Fig. 2 is showing the result, in this,
can be seen at 6 frequencies of working of the antenna,can
concluded that the antenna is working at the ideal reflection
coefficient.
= 0.243 0.051
Sm =
1
2
( 02n
0 n1
0.051
)(4 0.243
)
2
1
C. Width of dipoles
The width of the dipole, once the design is fixed by the
width of the largest dipole is obtained directly from the scale
factor of the antenna. The larger width of the dipole is taken
equal to the power line.[4]
Number N
Separation S(mm)
1
24
2
21
3
19
4
16.5
5
14.8
6
22
Frecuencia (GHz)
Lenght L(mm)
Width W(mm)
1.8
62
59.8
2.64
3.5
57.6
2.27
4.2
50
4.7
44
1.87
6.6
39.6
1.67
The next step, is connect the loop with other similar loop,
therefore, first, prove connecting two loops with a coupler, in
this case, a transmission line.
Through a sweep of the simulation through different
frequencies, beginning in 0 GHz and ending in 10 GHz,
can on obtained the results of antenna about impedances.
Showing a interesting results, because after of optimization,
has gotten a very good approximation, at 1.8 GHz, it is the
operating frequency.
Fig. 3. Bandwidth
Number N
1
2
3
4
5
6
Frecuencia (GHz)
1.8
3
3.5
4.2
4.7
6.6
Bandwidth (GHz)
0.28
0.215
0.16
0.095
0.12
0.08
Bandwidth (percent)
15
7.16
4.57
2.26
2.55
1.21
R EFERENCES
[1] [1] J. A. Encinar, ?Recent advances in re?ectarray antennas,? inProc.EuCAP, Barcelona, Spain, 2010.
[2] [2] M. Bercigli, P. D. Vita, R. Guidi, A. Freni, P. Pirinoli, L. Matekovits,
G. Vecchi, and M. Bandinelli, ?Hybrid SFX/MLayAIM method for the
analysis and optimization of large re?ectarrays and planar arrays with
metallic lenses,? inProc.EuCap, 2010.
[3] [3] J. Vian and Z. Popovic. ?Smart Lens Antenna Arrays? Microwave
Symposium Digest, 2001 IEEE Constantine A. Balanis. ?Antenna Theory.
Analysis and design?. 2nd edition. John Wiley and Sons,1997.
[4] [4] K.C. Gupta, R. Garg, I. Bahl and P. Barthia. ?Microstrip lines and
slotlines?. 2nd edition, Artech House, 1996.
IV. C ONCLUSIONS
A log periodic antenna type is antenna impedance
parameters or whose radiation is a periodic function of the
logarithm of the frequency of operation. The design of these
antennas is made from a certain size as the size of a dipole
or separation which are multiplied by a constant.
The advantage of the logarithmic antenna has a driven
element, but that power in its entirety. This results in a
higher bandwidth and impedance couples within all working
frequencies of this antenna is achieved.
The receiving of the signal or its active region continuously
changes depending on the frequency, which in the lowest
frequency of operation, the element is long and the other