I. INTRODUCTION
The popularity of the wireless communication is an
extension of the success of WiFi in making data
communication highly accustomed in daily life. The low cost
data communication thru WiFi services makes 3G, which is
notorious with high cost, difficult for market expansion. The
4G mobile system was released almost immediately afterward
for its outstanding capability in high speed data
communication and the general expectation of more
convenience in mobile life. However, the frequency
bandwidth needs to cover 2.3-3.8GHz and 4.9-5.925GHz to
meet the requirement for a combination of the systems of
WLAN and WiMax. In [1] isa double-T monopole antenna
with a bandwidth of high frequency smaller than 300MHz that
cannot fully meet the WLAN application. In [2] is a doubleloop antenna that generates sufficient bandwidth for WLAN
but uneven radiation pattern. In [3] is a microstrip-fed dipole
antenna with a bandwidth of high frequency smaller than
400MHz, unable to fully assure the WLAN application. In [4]
is a dipole antenna with internal matched circuit that can be as
small as 12mmu45mm. In [5, 6] are dual-band monopole
antennas with parasitic element matched can meet the
bandwidth requirement yet again, radiation pattern uneven. In
[7] is another compact microstrip-fed dual-band coplanar
antenna but with a large value of cross-polarization. In [8] is a
sleeve dipole antenna incorporating two separate dipoles ofdifferent arm lengths printed on two sides of a dielectric
substrate to signify a dual-band oscillation at 2.4 and 5.5GHz.
It has better frequency bandwidth and gain value for WLAN
application. In [9] presents anultrawide-band(UWB) antenna
with a ground of bigger size and a smaller circular element. In
[10] presents a dual-band antenna that excites two separate up
and down radiators to generatea dipole-like characteristic
with a microstrip-fed line. The frequency band and gain value
of this antenna can meet the requirement of WLAN
application of America.
A simple design of multiband printed antenna operating at
2.4/3.4/5.2/5.8 GHz is proposed in this paper, the prototype
of it fabricated and experimentally tested. The measured
VSWR 2:1 bandwidths are 1.82 GHz and more than 1.1 GHz
in the 2.4- and 5.2-GHz bands, respectively. The VSWR,
characteristics of radiation patterns and the antenna efficiency
will be specified in the followingsections. All the simulations
in this paper are conducted by HFSS software. Measurements
are carried out by R&S ZVL (9 kHz-6GHz).