Analysis of Multilayer Patch Antenna

This paper analyzes the stacked patch antenna. The anticipated antenna employments gap coupled procedure. The frequency can be adjusted by switching, which can underpins numerous frequency ranges between 2 GHz to 6 GHz with ideal return loss and fine execution. The proposed antenna improves the assembly of aperture-coupled multilayered stacked patch to extend the transmission capacity. This plan employments diverse structures of the gap openings, is engraved onto the ground plane couple with nourish line and stacked fix. The gap spaces are utilized to emanate the waves for the particular transmitting patches to realize the recurrence re-configurability. In ON state the radio wire is anticipating its working point at double frequencies as 3.2 GHz and 4.2 GHz. In OFF state the radio wire can reverberate at 5.3 GHz. These frequencies are well reasonable for higher recurrence applications like WLAN and Wi-MAX. Keywords— Reconfigurable antenna, Microstrip Patch, Radiation pattern, S-parameters, Stacked patch


INTRODUCTION
Reconfigurable antenna was to begin with presented in 1998 [1][2][3][4][5][6][7][8]. The multifunctional antennas were concentrated more on the characteristics of re-configurability. The ordinary antenna cannot be powerfully altering the parameters, while reconfigurable antenna have the responsibility to tune different antenna parameters. The dynamic fine-tuning of parameters is characteristically accomplished by controlling a specific switch conduct. The antenna parameters can be effectively balanced by controlling a certain switching behavior [9][10][11]. Reconfigurable antenna is utilized to diminish the undesirable impacts from co-site interference and jamming. It exchanging the different parameters like working frequency, radiation, gain and polarization, all parameters can be reconfigured with a single radio wire. The antenna reconfigurablity leads to a impressive enhancement in radio wire execution [13][14][15][16]. The frequency determination at certain range and radiation properties was accomplished [6].
By changing the antenna radiation pattern could be used to avoid noise source with improved security and energy storage by improved directing signal concerning intended direction. Hence observed that huge demand of reconfigurable antennas in the fields of wireless communications and other applications.

II. PROPOSED ANTENNA STRUCTURE AND DESIGN
The existing Frequency-Reconfigurable Stacked patch antenna employments H-shaped patch [13], it can be altered as X-shaped patch and named as Dual-Band X-shape Reconfigurable antenna. The proposed antenna has X-shaped carve at the top and the bottom side. By altering the shape it'll reverberate at diverse frequencies so that it can be utilized for double band applications. The re-configurability of the antenna can be accomplished utilizing additional small patches within the bottom side. It can be utilized to switch ON or OFF state of the proposed structure. The general microstrip patch antenna design equations are displayed in this section. It can also use to for the desired wireless communication applications. The width of the microstrip patch can be calculated using the equation (1).
The velocity of light is C. The relative permittivity of the substrate is,e The relative permittivity of the substrate is calculated first and the effective value can be computed using the equation (2) (2) Where, The relative permittivity of the insulating material is e r .
The elevation distance of the substrate is h. The depth of the dielectric is W.
The width is calculated first and the extended length is determined using the equation (3).
Where, eff  is the relative permittivity effective value of the dielectric material.
The value of the effective length of the patch is to compute the normal Length and the substrate. The effective length can be computed from the equation (4). The actual length can be computed using the equation (5).
Where, L eff is the effective value of length L  is the extension of length.
Feed line width can be modeled using the transmission characteristics and the impedance is given in the equation (7)   The aperture coupled microstrip antenna layers and switching circuit is appeared in Figure 1(a) and Figure 1 Figure 2. All substrate dimensions are 52 mm x 52mm. Each substrate thickness is 0.8 mm and air-gap is 3 mm and the thickness of the patch is 0.035 mm. The ground plane has pair of aperture slots (Xshape or I-shape) X-shape width is 10 mm and spread is 3mm. For I-shape width is 13 mm and the length is 1mm. Figure 3 shows the simulated X-shaped patch antenna using Computer Simulation Technology Microwave Studio. It has two modes of operation. Each mode is synthesized differently and its output is measured. In ON mode, RF switch will be present in the feed-line for simulation the copper strip is used. In OFF mode, the copper strip is removed indicates that no switch will be present in the feedline.

IV. PROTOTYPE OF PROPOSED MULTILAYER APERTURE COUPLED ANTENNA
The Proposed antenna is designed about the FR4-epoxy substrate along a dielectric constant of 4.3.The printed circuit board (PCB) is between the dimension of 52 x 52 mm on that the copper is printed with the thickness of0.035 mm and the substrate thickness of 0.8mm.The high frequency reconfigurable multilayer patch antenna is a stacked layered antenna so the PCB are designed separately as shown in Figure (11) and they are assembled in a stacked manner and tested by the use of Network analyser. During ON mode the copper strip exists in the feed-line as switch. In ON state all the two aperture slots are activated and the field emits in accordance with the particular layer therefore enabling it in accordance with activating state. The connection made between higher and lower patch and linked together to become a stacked patch, and produce a lower operating frequency.
In OFF state, the radiating strip is eliminated suggests that no switch will remain current in the feed-line. In  The comparison instituted between simulated and measured results. The executed results show that the stacked aperture coupled microstrip patch antenna with cross cut shaped patch will outturn an excellent outcomes all through ON and OFF state. There is a tradeoff in simulated and measured results. The mismatch among simulated or measured outcomes due to air-gap filling. It can be precisely matched by filling the air-gap using foam. The arrived results can be compared together with previous outcomes [1][2][3][4][5][6][7][8]

V. CONCLUSION
The synthesis of Reconfigurable Stacked Patch has been performed using Computer Simulation Technology (CST) Studio software. Its return loss, field pattern and other antenna characteristics are obtained. The frequency re-configurable multilayer antenna is prototyped and the parameters are observed. The outcomes show that the projected antenna supports dual band during ON state and single band during OFF state.so that they can be used various applications in the frequency range of 2 GHz to 6 GHz. The gain of the antenna is enhanced and it is on 6dB. The observed outcomes show that the projected antenna is well suitable for wireless Wi-MAX and Wi-Fi applications. It is absolutely challenging to achieve re-configurability using active devices along with microstrip patch antenna. This problem can be rectified using tiny metallic patches that acts as a switch according to enhance the re-configurability together with decreased cost. The future scope of this proposal is to combine more elements in the array form to improvise the gain and bandwidth.