Paper proposes novel approach for design of broadband antenna with multi band property. The rectangular microstrip antenna is realized by ‘I’ shape with vertical slots defected ground structure (DGS) for wireless LAN (WLAN) applications. The paper represents comparative study of results of vertical slotted DGS and ‘I’ shape vertical slotted DGS. By using FR-4 substrate designed antenna resonates at 5.516 GHz, 7.932 GHz and 9.825 GHz with bandwidth 341.6 MHz, 455 MHz, 342.69 MHz and return loss of -26.45 dB, -20.48 dB and -12.84 dB respectively. Proposed antenna uses concept of DGS which leads to improvement in return loss, bandwidth, gain, voltage standing wave ratio (VSWR) etc. Addition of vertical slot improves multiband characteristics. Ground area that is defected reduces size of antenna. A negative value of return loss shows very less losses in antenna. VSWR for proposed antenna is less than 2. Also gain of proposed antenna with ‘I’ shape vertical slot DGS is improved than that of existing vertical slot DGS antenna. This proposed method for designing of DGS antenna results in simpler structure which is easy to fabricate.Designing and simulation of the antenna is carried out by using IE3D software which uses concept of method of moments. Results show that an excellent cross polarization in antenna can be achieved by using proposed geometry of DGS. Hardware results shows that designed antenna resonates at 5.535 GHz and 9.88 GHz with return loss -16.80 dB and -28.69 dB and bandwidth 221 MHz and 590 MHz respectively. Simulation results and measurement results are presented to demonstrate feasibility of design.