 Rectangular Notch Microstrip Antenna for Dual-Band Operation Rajesh Kumar Vishwakarma, Ravi Kumar Department of Electronics & Communication Engineering, Jaypee Institute of Engineering and Technology, A. B. Road Raghogarh, Dist-Guna – 473226, (M.P) INDIA E-mail : rkv_786@yahoo.com ; ravi.kumar6@gmail.com Abstract – Microstrip antenna consists of a radiating patch on one side of dielectric substrate which has a ground plane on the other side. The antenna element it self may be square, rectangular, circular, triangular etc and may have more than one feed. An experimental study of dual band characteristics of single layer rectangular microstrip antenna is presented. For feeding of the antenna direct microstrip coupling with proper matching transformer has been used. The optimized notch dimension has been taken for two resonant frequencies. The resonance frequency changes with the variation in the length and width of the notch. The VSWR is measured with the help of network analyzer. Key words – Microstrip antenna, Notch antenna, Dual band antenna, Network analyzer I. INTRODUCTION Microstrip antennas are receiving much attention at present because they offer many practical advantages such as small size, lightweight and a low profile 1 . Application includes radar, satellite communication wireless networks, and mobile communication and microwave sensors. One of the principal disadvantages of such antenna is narrow bandwidth. Recently several papers have been published treating notch microstrip antenna to achieve dual band characteristics 2, 4 . The major limitation of microstrip antenna lies in its limited bandwidth. Several methods have been reported in the open literature 5, 7 to improve the bandwidth of the microstrip antenna such as thicker substrate use of parasitic elements, proximity coupling of the feed line, and stacked microstrip antennas. Recently Palit 8 et al has reported a microstrip antenna by properly cutting a notch inside the radiating element. This properly fields enough BW for dual band frequency and broadband operation. The idea is extended by designing variation of length and width of the notch antenna. In the present work, and the effect of notch length and width on the resonance frequencies have been carried out. II. FEEDING NETWORK The microstrip line method is easy to fabricate simple to model and match by controlling the inset cut position in the patch in the fig.1. Matching transformers which transform the input resistance of patch to 50 ohm coaxial cable. The ratio W/H of the microstrip line used for feeding network can patch to found as to follows. The effective dielectric constant change with the ratio of strip width W to thickness h as 0.5 w h 10 1 2 1 r ε 2 1 r ε eff ε -       ⋅ + ⋅         - +         + = (1) when then define eff o Z Z ε = (2) where Z is the strip impedance. The formula for Z 0 = for W/H 1 ≤ can be given as       + = H w w H In z 4 8 60 0 for 1 ≤ H W (3) 6 0 1 44 . 0 42 . 2 120       - - + = W h W h h W Z π for 1  h W (4) we can find the impedance when W/h is known but most design problem required the otherwise i.e. give Z fin W/h, So equation (1) and (3) or (4) in an interactive process are used to find W/h when W/h =1, We first find Z 0 of W/h =1and then eff ε and impedance are calculated as.         - +         + = 2 1 r ε 2 1 r ε eff ε , 1 = h W (5) eff o Z Z ε = and ) 1 ( eff o Z Z ε = (6) where       = = 1 6 . 126 0 h W Z If Z 0 is greater than Z 0 (1) then W/h using is less or equal 1 Case 1 When 1 ≤ H W then           -             -       = 8 60 exp 60 exp 2 2 0 0 Z Z h W (7) starting with ( 29 1 eff ε we solve for h W using this value. 978-1-4244-2690-4444/08/$25.002008 IEEE