The design of lightweight, robust and low-cost
antenna systems for wireless communication is an area of foremost concern for antenna manufacturers. A
good and simple choice is based on the microstrip patch radiator (James and Hall, 1989),
one of its main drawbacks is its narrow operation band. Also miniaturization of
microstrip patch antennas is a very challenging field to investigate because of the
increasing interest in integrating such antennas in Monolithic Microwave Integrated
Circuit (MMIC). The conventional dimension of microstrip patch antenna is around
half wavelength. Several miniaturization techniques are reported such as, using
high permittivity substrate materials (Anguera et
al., 2004), magnetic substrate or superstrate materials
(Kwon et al., 2003), short circuits (Row, 2005), increasing electrical
lengths (Guha and Siddiqui, 2004) and/or combination of these methods.
By only adjusting the length, width, and position of the slots, one can
obtain satisfactory performances. It has been reported that, by adding
a slot on patch of various shapes, the antenna can be operated at two different frequencies.
One resonance is due to the fundamental mode of the main patch and the
other is due to the fact that the current along the edges of the slot introduces
an additional resonance (Kwon et al., 2003). The increase in the number of the
slots, with different dimensions at appropriate positions on the patch surface,
indicates an increase in the number of resonance frequencies. In this paper, by adjusting
the slots length, width and position, we can control the resonating frequency values
and the reflection coefficients (matching), respectively. By loading properly
arranged inverted shaped patch as well as horizontal slots on the surface of
rectangular microstrip patch, the dual-band frequency of a single feed rectangular patch
antenna can be achieved. |
