Design and Implementation of Dual-Stacked Identical Yagi Antenna For UHF Applications

International Journal of Trend in Scientific
Research and Development (IJTSRD)

International Open Access Journal
ISSN No: 2456 - 6470 | www.ijtsrd.com | Volume - 2 | Issue – 4
Design and
nd Implementation of Dual-Stacked
Stacked Identical
Yagi Antenna for UHF Applications
J. Ilouno1, M. Awoji2 , J. E. Onuh1
1
Physics Department, University of Jos, Jos, Nigeria
2
Physics Department, Kwararafa University, Wukari, Taraba State, Nigeria
ABSTRACT
This paper presents the design and implementation of in respond to an applied alternating
ternating electric current
dual-stacked
stacked identical Yagi antenna. An Antenna is an (Warren and Gary 1998). ). Antennas are generally used
essential terminal device in all forms of in systems such as; radio and television broadcasting,
communication and radar systems. Without an point to point radio communication, radar and space
antenna there would be neither communication system exploration. In addition to receiving or transmitting
nor radar system. An antenna acts as a source as well energy, an antennana is usually required to optimize or
as a sensor of electromagnetic waves. The design was accentuate the radiation in a specific direction and
done using an online Yagi calculator software (AN (AN- suppress it in others. Thus, antennas must act as
SOF Antenna Simulator) which calculated the length, directional devices. An antenna can either be a piece
diameter, and the spacing of the materials (elements of conducting wire, an aperture, a patch, an assembly
and boom) used in the construction. The Yagi antenna of element
ent (array), a reflector or lenses (Kraus,
( 1988).
implementation was carried out using a cutting Antennas could be divided into four basic types
machine in cutting off various lengths of the elements depending on their performance characteristics
specified by the Yagi calculator software. Thereafter, namely; electrically small antennas, resonant
the elements were arranged on the aluminum boom antennas, broadband antennas and aperture Antennas
and the coaxial cable impedances and dipole element (Balanis, 1989, 1992).
were matched. The identical Yagi antennas were
stacked (1020 mm center er to center spacing)vertically Yagi antenna is an example of a resonant directional
leading to an increase in gain of 15.4 dBwhen antenna consisting of driven elements (active
compared with 12.7 dBgain obtainable from a single components) and parasitic elements (passive
Yagi antenna and larger capture area (effective components) as seen in Figure 1.
aperture).This design was able to solve the problems
of underground noise, interference,
rference, low picture
quality, low gain, and large beamwidth associated
with a single Yagi antenna. This antenna can be used
for UHF (300–3000 MHz) applications.
Keywords: Antenna, Yagi, Dual-Stacked,

Stacked, Gain
1.0 Introduction
An antenna is an arrangement of electrical conductors
designed as transceivers of radio waves (Carr, 2001;
Volakis, 2007).
). Antennas convert Radio Frequency Figure 1: Yagi antenna
(RF) electrical currents into ElectroMagnetic (EM)
waves that generate a radiating electromagnetic field
@ IJTSRD | Available Online @ www.ijtsrd.com | Volume – 2 | Issue – 4 | May-Jun

Jun 2018 Page: 1368
International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456-6470
The driven elements are connected directly to the
transmission line (coaxial cable) and receive power
from the source. Whereas, the parasitic elements are
not connected to the transmission line and receive
energy only through mutual induction. Theparasitic
elements (directors and reflectors) modify the
radiation pattern of the radio waves emitted by the
driven element and direct them in a narrow beam in
one direction and are arranged parallel to the driven Figure 2: Vertical dual-stacked antenna
elements. The reflector is usually longer than the
driven element by 5% and acts as a concave mirror While stacking two identical Yagi antennas side by
because it reflects the electromagnetic energy incident side in a horizontal plane significantly narrows the
on it from the driven elements. The director is shorter horizontal beam-width angle. That is, the antenna
than the driven element by 5% and acts as a convex combination “sees” fewer interfering signals arriving
mirror as it beams up the incident energy from driven from the sides while its vision up and down (in a
element (Milligan, 2005). vertical plane) is virtually unaffected. In this process,
gain increases approximately 1.2 dB over that of a
Antenna gain is the measure of the ability of antenna single antenna (Straw, 2000). The stacking distance
arrays to concentrate the radiated power in a given can be calculated using Equation 2 (Milligan, 2005).
direction. High-gain antenna radiates energy in a
particular direction whereaslow-gain antenna radiates
energy in all directions equally. Gain is described S= (2)
using terms suc has antenna gain, power gain, where
directivity or directive gain. The antenna gain of the S is the stacking distance and BW is the Beam-Width
Yagi antenna isgreatly dependent on the dipole gain angle
and the number of elements; and is given by
(Ochalaand Okeme, 2011): This research work is carried out to solve the
problems of underground noise, interference, picture
G = 1.66 N (1) quality, low gain, and large beam-width associated
with a single Yagi antenna by stacking two identical
where Yagi antennas. Vertical stacking was used in the
1.66 is the dipole gain and N is the number of implementation because of the higher gain and greater
elements coverage area.
When Yagi antennas are stacked, there is an increase 2.0 Materials and Methods
in gain and a decrease in the beam-width. The
increased gain is due to the reduction in beam-width. Materials
There are two types of stacking namely; vertical The materials used are:
stacking and horizontal stacking (Blake, 1996; 1. Aluminum Boom
Balanis, 2005, 2008). Stacking two identical antennas 2. Screw nails
on a common vertical mast as seen in Figure 2 3. Elements
significantly narrows the vertical beam-width angle. 4. Coaxial cable (75 Ω)
That is, vertically stacked antennas effectively reject 5. Plastic insulators
those interfering signals arriving from above or below 6. Tape
their horizontal plane than that of a single antenna. In 7. Drilling machine
this process, gain increases with about 2.5 dB over 8. Hacksaw
that of a single antenna (Straw, 2000). 9. Mast or pole for mounting of the antenna
Methods
Design of Yagi Antenna
An online Yagi antenna calculator (AN-SOF Antenna
Simutor) was used for the simulation with design
@ IJTSRD | Available Online @ www.ijtsrd.com | Volume – 2 | Issue – 4 | May-Jun 2018 Page: 1369
frequency of 889 MHz. The Yagi antenna designed Table 2: Simulation Result
has 8 elements: a reflector, a driven element, and 6 Element Distance for Distance expressed as
directors with dimensions shown in Table 2 driving point fractions of the
of driven wavelength
Design Implementation element(mm)
The antenna was constructed using aluminum rods for Reflector 139 0.28
antenna elements, 2cm-squared metal rodas boom, Director 55 0.11
hacksaw for cutting the materials, gimlet for drilling 1
holes, screw nails for fastening theelements to the Director 110 0.23
boom, measuring tape, welding machine, 75-ohm 2
coaxial cable as transmissionline and feeders to house Director 165 0.34
the terminals of the folded dipoles.The elements were 3
first measured as stated in Table 2. Holes were drilled Director 275 0.56
at the midpoints of the aluminum rods and boom 4
constructed. A reflectorunit and six directors were cut Director 385 0.80
out. Holes were drilled on them and the directors were 5
screwed into their appropriate positions. Plastic Director 495 1.02
insulators were used to insulate the directors form the 6
supporting boom.The folded dipole (driven element)
was constructed by folding aluminium rod on a Table 3: Normalized Spacing between elements
bending jig to obtain the folded dipole.A junction box
Relative Spacing
was used to support the folded dipole on the boom.
Openings were made on the side of the junction box 𝒔𝟎,−𝟏 0.29λ
using a drilling machine to allow fitting of the dipole
and the coaxial cable. The feeder was fixed to the 𝒔𝟎,𝟏 0.110λ
director boom with screw nails and the terminal of the
folded dipole was then fixed to the inside of the 𝒔𝟏,𝟐 0.227λ
feeder. With the feeder and folded dipole in place, the
reflector and director units were fixed.The relative 𝒔𝟐,𝟑 0.227λ
spacing between elements for optimal reception was
𝒔𝟑,𝟒 0.227λ
determined as follows as shown in Table 3.The
antenna was duplicated and were stacked vertically at 𝒔𝟒,𝟓 0.227λ
1020 mm. Approximately one wavelength spacing (at
lowest channel frequency) between antennas was 𝒔𝟓,𝟔 0.227λ
maintained. Finally, the folded dipoles were
connected together by means ofa coaxial cable which
serves as the transmission line. Table 4: Single and Stacked Yagi results compared
Parameters Single Yagi Stacked Yagi
3.0 Results Forward gain 12.720 dB 15.400 dB
Table 1: Length of rodrequired to produce resonant Backward gain 3.415 dB 4.394 dB
dipole Front-Back ratio 9.306 dB 11.006 dB
Length to Percent Resonant Dipole thickness Beam-Width 47 degrees 23.5 degrees
Diameter Shortening length class Signal strength 67% 76%
ratio(L/D) required Stacking distance _ 1020
5000 2 0.49λ Very thin
50 5 0.475λ Thin 4.0 Discussion
Stacking two identical Yagi antennas produced an
10 9 0.455λ Thick increase in 2.6 dB more forward gain as seen in Table
4. Vertical stacking reduces the vertical beamwidth
and also introduced extra sidelobes in the vertical
(elevation) radiation pattern. When antennas are
stacked only vertically, the horizontal radiation
pattern of the array will be the same as the individual 11) Volakis, J.G. (2007). Antenna Engineering
Yagi.Stacking too far apart will increase the vertical Handbook. 4th Ed.: McGraw-hill.
sidelobe levels and make the vertical pattern narrower
12) Warren L.S. and Gary A.T. (1998).Antenna
as the sidelobes eat into the main lobe. Wider stacking
Theory and Design. 2nd Ed, New York:
will also make the antenna bigger and less strong.
JohnWileyand Sons Inc..
Closer stacking will make the vertical pattern wider,
and decrease the vertical sidelobelevels. Although this
will result in serious loss of gain if taken too far, it
may be a valid trade-off to obtain a cleaner vertical
pattern. Vertical stacking improves both gain and
vertical directivity. This helps reduce airplane flutter
and attendant picture roll, and certain types of ground
noise and ground reflections.
5.0 Conclusion
The results of this finding have shown that dual-
stacked Yagi antenna offers high gain compared with
single Yagi antenna in operation coveringchannels in
UHF bands. This design when properly matched to a
feeder cable can solve the problems of underground
noise, interference, low picture quality, low gain, and
large beam-width posed by single Yagi antenna.
Reference
1) Balanis, C.A. (1989). Advanced Engineering

Electromagnetics, Wiley, New York.
2) Balanis, C.A. (1992). Antenna Theory: A Review,
“pro’’. IEEE, vol. (80).
3) Balanis, C.A. (2005). Antenna Theory: Analysis
and Design, 3rd Ed. New Jersey: John Wiley and
Sons.
4) Balanis, C.A. (2008). Modern Antenna Handbook.
New York: John Wiley and Sons Inc..
5) Blake, L.V. (1996). Antennas. New York: John
Wiley and Sons.
6) Carr, J.J. (2001). Practical Antenna Handbook.
4th Ed. USA: McGraw-Hill.
7) Kraus, J.D. (1988). Antennas. New York:
McGraw-Hill.
8) Milligan, T.A. (2005).Modern Antenna Design.
New Jersey: John Wiley and Sons.
9) Ochala, I. and Okeme, I.C. (2011). Design and
Implementation of a High-Gain Compound
YagiAntenna. Advances in Applied Science
Research, 2 (6), 41-50.
10) Straw, D. (2000). The ARRL Antenna Book. 19th
Ed, USA: The American Radio Relay League.

Design and Implementation of Dual-Stacked Identical Yagi Antenna For UHF Applications

Uploaded by

Copyright:

Available Formats

Design and Implementation of Dual-Stacked Identical Yagi Antenna For UHF Applications

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Design and Implementation of Dual-Stacked Identical Yagi Antenna For UHF Applications

Uploaded by

Copyright:

Available Formats

International Journal of Trend in Scientific

Research and Development (IJTSRD)

Keywords: Antenna, Yagi, Dual-Stacked,

@ IJTSRD | Available Online @ www.ijtsrd.com | Volume – 2 | Issue – 4 | May-Jun

1) Balanis, C.A. (1989). Advanced Engineering

You might also like