_{1}

^{*}

The design of a seven-band stacked patch antenna for the C, X and Ku band is presented. The antenna consists of an H-slot loaded fed patch, stacked with dual U-slot loaded rectangular patch to generate the seven frequency bands. The total size of the antenna is 39.25 × 29.25 mm
^{2}. The multiband stacked patch antenna is studied and designed using IE3D simulator. For verification of simulation results, the antenna is analyzed by circuit theory concept. The simulated return loss, radiation pattern and gain are presented. Simulated results show that the antenna can be designed to cover the frequency bands from (4.24 GHz to 4.50 GHz, 5.02 GHz to 5.25 GHz) in C-band application, (7.84 GHz to 8.23 GHz) in X-band and (12.16 GHz to 12.35 GHz, 14.25 GHz to 14.76 GHz, 15.25 GHz to 15.51 GHz, 17.52 GHz to 17.86 GHz) in Ku band applications. The bandwidths of each band of the proposed antenna are 5.9%, 4.5%, 4.83%, 2.36%, 3.53%, 1.68% and 1.91%. Similarly the gains of the proposed band are 2.80 dBi, 4.39 dBi, 4.54 dBi, 10.26 dBi, 8.36 dBi and 9.91 dBi, respectively.

Antenna is a very important component of communication system. The enormous growth of mobile and satellite communication systems along with wonderful use of radars opens a huge demand to new kind of antennas such as small antennas, multi frequency antennas, and broadband antennas [

In the present paper, a multiband microstrip stacked patch antenna is introduced. The proposed structure is a planar structure having all the dimensions in mm. The proposed antenna is designed by using a substrate of FR4 having thickness 1.6 mm. This proposed antenna is having seven bands of operation. The entire investigation is based on equivalent circuit model. In [

The design of the proposed multiband antenna is depicted in

Microstrip patch with a dielectric cover is considered as a single patch with a semi-infinite superstore with re- lative permittivity equal to unity and the single relative dielectric constant (

in which W_{e} is the effective width and

where,

h_{1} = height between ground plane and lower patch;

W = width of the patch.

The equivalent circuit of the simple patch antenna is parallel combination of resistance (R_{1}), inductance (L_{1}) and_{ }capacitance (C_{1}) (

where

L = length of the lower patch;

y_{o} = Y-coordinate of the feed point.

c = velocity of light.

ΔL = fringing length for the lower patch.

Considering the top patch as a simple stacked rectangular microstrip patch, the values of resistance (R_{2}), inductance (L_{2}) and_{ }capacitance (C_{2}) can be given as

where

where

L_{2} = length of the stacked patch;

W_{2} = width of the stacked patch;

ΔL_{2} = fringing length for the top patch.

The equivalent circuit of the fed patch is shown in _{H} is resonance resistance after cutting the notches into the patch. The value of R_{H} can be calculated using Equation (7) and the

where

and

where C_{s} is the gap capacitance between two side strips [_{N}” is the impedance of the notch incorporated patch and is calculated from _{P} is the impedance of the initial patch and C_{m} and L_{m} are the capacitive and inductive coupling between two resonant circuits.

When a dual U-slots is cut into the stacked patch, current distribution changes which ultimately changes the resonance behavior of the patch. Due to this changing in the patch adds series inductance (_{2},

where

where

The value of C_{b} and L_{b} are calculated as [

Similarly we can analyze circuit concept of second U-slot which is parallel and compact to first U-slot on the upper patch.

The equivalent circuit of the proposed multiband antenna can be given as shown in

where

and

Thus the total input impedance can be calculated from

In which Z_{H} and Z_{U} are the impedances of initial and parasitic patches calculated from _{m} is the impedance due to mutual coupling between fed patch and stacked patch.

All the simulation results of the proposed antenna are given as Figures 6-8. Discussion of results have been explain in terms of S_{11} parameters, resonance frequencies, gains and radiation patterns.

The variation of reflection coefficient with frequency for the proposed multiband antenna is depicted in

the patch, the results are obtained as a multiband antenna with good gain, which is more useful as compared to dual band application presented in 2008. Radiation pattern of the proposed antenna is shown in

A stacked multiband proximity coupled microstrip patch antenna is presented. This antenna has a very simple structure printed on FR4 substrate. Multiband has achieved by using dual U-slot loaded stacked patch. The total volume of the antenna is 39.25 × 29.25 × 1.6 mm^{2}. The proposed antenna shows satisfactory multiband performance and good radiation pattern. Proposed antenna finds the application in C, X and Ku band which can be used for radar, VSAT, mobile and satellite communication.

Nagendra PrasadYadav, (2015) Double U-Shaped Slots Loaded Stacked Patch Antenna for Multiband Operation. Open Journal of Antennas and Propagation,03,9-17. doi: 10.4236/ojapr.2015.32002