Journal of Power and Energy Engineering, 2015, 3, 269-273
Published Online April 2015 in SciRes. http://ww w.scirp.org/journal/jpee
http://dx.doi.org/10.4236/jpee.2015.34036
How to cite this paper: Lai, W.-C. and Wu, C.-L. (2015) Effect of Metal and Magnetic Slab on Radiation Characteristics of
Monopole Antenna. Journal of Power and Energy Engineering, 3, 269-273. http://dx.doi.org/10.4236/jpee.2015.34036
Effect of Metal and Magnetic Slab on
Radiation Characteristics of
Monopole Antenna
Wen-Cheng Lai, Ching-Ling Wu
Department of Electronic Engineering, Ming Chi University of Technology, New Taipei, Taiwan
Received Dec emb er 2014
Abstract
The effect of metal and magnetic slab on the radiation characteristic of monopole antenna is stu-
died in this paper. The presence of metal slab ch an ge s the antenna r adiation patte rn and it also
increases the gain up to 4.6 dB. The radiation charac te ris tic of monopole antenna is determined by
the separation distance between planar monopole and metal slab. In addition, magnetic slab also
change s the antenna radia tion p att ern and it also increases the gain up to 3 dB. Metal slab makes
antenna generate reflection, but magnetic slab makes antenna generate refraction is their differ-
ence. As to the application sl ab, the initial pattern of the antenna without materials was omnidi-
rectional. However, when the materials were added, its pattern would change, making the antenna
to hav e other usages and transition effect. They will influence electromagnetic in power systems.
Keywords
Metal Slab, Magnetic Slab, Monopole Antenna, Radiation Pattern, Power Systems
1. Introduction
With the antenna’s pattern/frequency reconfigurability, the noise sources or intentional interference in a hostile
environment are suppressed or alleviated. The antennas of this sort have been reported, e.g. [1]-[7]. On the other
hand, the single turn square spiral microstrip antenna with both reconfigurable radiation pattern and frequency
was demonstrated in [8]. More details on the reconfigurable antenna designs and applications can be found in
[9]. In this paper, we introduce the effect of metal and magnetic slabs on the return loss, radiation patte rn and
gain of monopole antenna. In this study, a monopole antenna with an operation frequency of 2.4 GHz is em-
ployed to explore the variatio n of radiation characteristics due to the presence of two slabs placed at different
distances from the monopole antenna.
2. Experimental Setup and Met ho d
2.1. Experimental Setup
First, in Figure 1 shows that the setup of monopole antenna and either metal or magnetic slab. A metal or mag-

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270
netic slab is placed in parallel to the planar monopole antenna fed with microstrip. The distance between two
parallel plates is d, the thickness of slab is t and θ is the angle.
2.2. Experimental Method
The photograph of top, side, and bottom views of the fabricated antenna are shown in Fig ur es 2(a)-(d), respec-
tively. A styrofoam board is employed to control the distance d between the slab and the monopole antenna.
Since the styrofoam board is thin, a stack of foam board will be used to change the distance d little by little
(about 3 mm) with every piece added. Notice that the styrofoam board is fixed through scotch tape and the metal
or magnetic slab is placed on the ground plane side of the monopole antenna. The thickness of metal slab is 0.9
mm. The thickness of magnetic slab is 1 mm.
3. Experimental Res ult s
3.1. Return Loss of the Monopole Antenna as a Function of the S pac ing
The measured return loss against different spacing is shown in Fig ure 3(a), Figure 3(b) [10].
3.2. Variation of Pattern and Gain as a Function of d
Figure 4(a) and Figure 4(b) show the simulated and measured radiation patterns at the E-planes at the resonant
Figure 1. Schematic diagram of monopole antenna and either metal or magnetic slab.
(a) (b) (c) (d)
Figure 2. The (a) top, (b) side, (c) metal slab with bottom and (d) magnetic slab with bottom view of antenna.

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271
(a) (b)
Figure 3. The return loss of (a) metal slab and (b) magnetic slab of the monopole antenna as a function of the spacing.
(a)
(b)
Figure 4. Simulated and measured pat terns as a function of distance d between the (a) metal slab and (b) magnetic slab and
the ground plane of monopole antenna.

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272
(a) (b)
Figure 5. Measured gains as a function of distance d between (a) metal slab and (b) magnetic slab and the ground plane of
monopole antenna.
frequency (2.4 GHz). It is shown that the measured data are in excellent agreement with the simulated one. In
Figure 4(a), a metal slab with thickness of 0.9 mm is employed in the experiment. When metal slab is placed on
the ground side of the monopole antenna, the pattern changes significantly as the distance d increased. The
E-plane radiation pattern becomes directional compared to the one of the classical monopole at θ = 0˚. Again, in
Figure 4(b) [10], a magnetic slab with thickness of 1 mm is employed in the experiment. When magnetic slab is
placed on the ground side of the monopole antenna, the pattern also changes. The E -plane radiation pattern be-
comes directional compared to the one of the classical monopole [11] at θ = 0˚, 180˚. The pattern of the antenna
is omnidirectional when the magnetic slab is absent. The pattern changes gradually as the magnetic slab moves
farther from the grounding plate of the antenna.
3.3. Effect of d on the Gain of the Ground Shielding
Figure 5 shows the gain variation of antenna system as a function of d for the metal or magnetic slab. In the
metal slab case as Figure 5(a), the antenna gain always less than without slab of monopole antenna at θ = 180˚.
When d = 10.5 mm, the antenna gain start large than without slab of monopole antenna at θ = 0˚. When d =
35.86 mm, it can increase the antenna gain to 4.6 dB at θ = 0˚. In the magnetic slab case as Figure 5(b) [10], the
gain is less than 0 dB as d < 15 mm. As d > 20 mm, the magnetic slab acts as a reflector so that appreciable gain
is obtained. On the other hand, Figure 5 shows the antenna gain as a function of d for different values of mag-
netic slab thickness at θ = 180˚. The antenna has appreciable gain for 10 mm < d < 30 mm. The optimal gain
occurs when 14 mm < d < 16 mm. The max. gain 3 dB holds for a large range of d.
4. Conclusion
A planar monopole antenna with reconfigurable radiation pattern is presented. It is found that, the presence of
metal slab with thickness of 0.9 mm will yield reflection e ffects, which can increase the antenna gain to 4.6 dB
at θ = 0˚ and produce desirable radiation pattern. In other hand, the prese nce of magnetic slab with thickness of
1 mm will yield refraction or reflection effects, which can increase the antenna gain to 3 dB at θ = 180˚ and
produce desirable radiation pattern. The measured results are in good agreement with the simulated results, as
shown in Fig ure 4. So we can see that metal slab better than magnetic slab in this verification. It seems that we
placed items inadvertently in the general household, but it inducing electromagnetic will influence the power
system [12].
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