In the proposed paper, a uniplanar asymmetric coplanar strip (ACS) fed antenna with closed V-shaped radiating patch of size  printed on FR4 substrate with loss tangent ( =0.02, height (h)=1.6mm, and dielectric constant of 4.4 covering WiMAX, X-band and WLAN applications is presented. The proposed closed V-shaped radiating patch is formed by joning two rectangular stubs. The resultant shape of the radiating patch is obtained by adding rectangular strips to feed line until desired multiband results are achieved.  The advantage of this structure is that it forms simple configuration as well as helps the overall antenna in attaining three distinict useful frequency band with good impedance matching for S11-10 dB criteria. The proposed ACS fed antenna operates at 3.1 (WiMAX), 5.0 (WLAN) and 9.9 (X-band) GHz with impedance bandwidth ranging from 2.7-3.9 GHz, 4.4-5.5 GHz and 9.5-10.3 GHz in simulation. Under measurement the proposed antenna shows multiband phenomenon at 3.2, 5.3 and 9.7 GHz with impedance bandwidth ranging from 2.8-3.7 GHz, 4.6-5.4 GHz and 9.4-10 GHz, respectively. The antenna exhibits simulated gain of 2.51, 1.18 and 1.96 dB at the corresponding frequency bands of 3.1, 5.0 and 9.9 GHz. The key parameters of the antenna like length and width of the multi-branched strips are optimized to get the multiband operation. The deisign simulation is carried out in Ansys HFSS (High frequency Simulation Software) where different characteristics of the proposed antenna are investigated. The evolution and optimization process is dealt in detail with the help of S11, VSWR, current distributions, radiation patterns and gain.

This research paper presents two different types of multiband patch antenna. The first design is a dual-band antenna and the second design is a quad-band antenna. Both the antennas have a compact size of , and is designed on FR4 substrate with loss tangent (=0.02, height (h)=1.6 mm, with dielectric constant of 4.4. The dual-band antenna operates at frequencies 3.9 and 5.71 GHz. These dual band operations are accomplished by utilizing L-shaped slot in the ground part and T-shaped slot in the radiating part of the patch antenna. The gain corresponding to the two frequency bands are 1.27 and 1.35 dB, respectively. The quad band antenna operates at frequencies 3.6, 4.9, 7.4 and 8 GHz. The gain corresponding to these frequencies are 0.18, 1.69, 2.25 and 3.99 dB. For achieving quad band operation from the dual band antenna the back plane L-shaped slot is modified by cutting a rectangular strip in the middle, hence dividing it into two different slots. The front plane is also modified by introducing two rectangular strips to the T-shaped patch. The proposed antenna shows multiband and has the advantage of simple structure compact size and good impedance matching. All the simulations of the proposed design are carried out in HFSS v.13.0.