antenna is commonly used for wireless communication system because of many
advantages like low-cost, low-profile and easy fabrication. However, microstrip
patch antenna have several disadvantages such as narrow bandwidth and low gain.
The incresing growth of wireless system needs miniaturized antenna. The size of
antenna must be reduced due to the development of technologies wireless systems
becoming more compact. There are several miniaturization techniques to reduce
size of antenna.
One of the techniques is by using
high permittivity material. The wave propagation will increase within the
substrates and radiation effeciency is lower due to losses are increasing and
also decrement of bandwidth. A lot of different materials have been use to
miniaturize the antenna. In (H. M. Chen, Y. K.
Wang, Y. F. Lin, C. Y. Lin and S. C. Pan, April 2009), the ceramic
substrate is used in square ring microstrip patch antenna with dielectric
constant of 58. Circular polarization was achieved by simple microstrip feed
line through coupling on the same plane. 50% of size reduction was achieved
with 1.1% of impedance bandwidth at 1.573 GHz. By using magneto-dielectric
substrate for miniaturization of microstrip patch antenna, 65% of size
reduction was achieved at 2.45 GHz (P. M. T. Ikonen, K. N.
Rozanov, A. V. Osipov, P. Alitalo and S. A. Tretyakov, Nov. 2006).
The most commonly technique to
miniaturize antenna is slots on the patch. Various slots with different lengths
were used in (S. I. Hussain Shah, S.
Bashir and A. Altaf, 2014) on the patch antenna such as U and L
shaped slots. By using shorting pin, the patch and ground plane were shorted
causing an increment of electrical path length for current flow and 86% of size
reduction. The antenna is operated at multiple bands of frequencies and gain at
the frequency range is 3.5 dBi to 6.6 dBi. A single layer microstrip patch
antenna on FR4 substrate is designed in (Kamboj, V., Saini, G.,
and Saini, A., July 2016)
using etching polygon, rectangular and square shaped slots to miniaturize and
improve the bandwidth. The antenna is operate in S-band and the size of antenna
have bee reduced to 37.8% with 260 MHz of impedance bandwidth and 2.36 dB of
A patch antenna was designed using
metamaterial in (T. K. Upadhyaya, V. V.
Dwivedi, S. P. Kosta and Y. P. Kosta, 2012) for low frequency
domain for dual transmit and single receive frequency. The combination of split-ring resonator (SRR)
and thin wires (TW) which is made up of copper is used as substrate of patch
antenna for generation of artificial composite material. FR4 is used as
dieletric substrate material. The performance of antenna showed -20 dB return
loss was achieved with 80% of size reduction. An AMC structure is used on a
microstrip patch antenna where AMC act as a ground plane in (F. Rahmadani and A.
The antenna is designed to resonate at 2.45 GHz and it is deployed on FR-4
substrate. The proposed antenna has 100 MHz of bandwidth with return loss of
12.8 dB and 1.53 of gain. The size of the antenna is reduce more than 31% with
incorporation of AMC structure. Table 2.1 showed the summary of miniaturization
techniques microstrip patch antenna.