The design of proposed antenna started with consideration of a CPW fed circular patch having patch radius 9.3 mm. This antenna is designed on glass epoxy FR4 substrate material (relative permittivity ε r = 4.4, substrate height h = 1.59 mm and loss tangent 0.025) having size 30 mm x 20 mm x 1.59 mm. Circular Patch Antenna with Defected Ground for UWB ABSTRACTThe design and performance of coplanar waveguide fed modified circular patch antenna for possible application in ultra wideband communication systems with band rejection for upper wireless local area network band (5.15 GHz -5.85 GHz) is reported. This antenna is designed on glass epoxy FR4 substrate having size 30 mm × 20 mm × 1.59 mm. The coplanar waveguide fed circular patch antenna is modified by introducing L shaped slits in ground plane and U shaped slot in patch and performance analysis of antenna is simulated by applying CST microwave studio simulation software. Different designed antennas were tested with available experimental facilities. The developed end product shows a nice matching with feed network at frequencies 2.62 GHz, 3.94 GHz and 8.50 GHz and provides 10.38 GHz (3.33 GHz -13.71 GHz) impedance bandwidth with wireless local area network 5.5 GHz (4.74 GHz -6.15 GHz) band rejection. The co and cross polar patterns in elevation and azimuth planes at two frequencies namely 2.62 GHz and 3.94 GHz are obtained which dictate that co-polar patterns are significantly better than cross polar patterns. The simulated peak gain of antenna is close to 3.86 dBi and gain variation with frequency shows a sharp gain decrease in the frequency range 4.74 GHz to 6.15 GHz. The length L g and width W g of the ground plane of considered geometry are 8.0 mm and 7.0 mm, respectively. The gap G p between patch and ground is 1.8 mm whereas the gap g between the strip line and ground plane is 0.50 mm as shown in Fig. 1(a). The length f L and width f w of feed line are 10.8 mm and 5.0 mm, respectively. The considered feed line is electrically thick and contributes in the overall performance of antenna. These design parameters are obtained after extensive optimizations. A comparison of S 11 variation of this geometry with the geometry having same radiating element on an infinite and finite ground planes is shown in Fig. 1 This antenna is then modified in two steps to improve its performance. Keywords CPW Feed Circular Patch with Defected Ground PlaneIn the first step of modification, two L-shaped slits are introduced one by one to make ground plane defective as shown in Fig. 2. The slit length in ground a and slit width in ground b are taken 5 mm and 3 mm, respectively. The slit width S w1 is optimised by simulating (S 11 ) parameter of antenna considering four different slit widths as shown in Fig. 2(b). Finally for the present work, slit width equal to 0.3 mm is selected because for this slit width, best performance from antenna is realised which is shown in Fig. 2(c). A comparison between simulated and measured reflection coefficient (S 11 ) as a function of frequency...

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In this communication, the design and performance of micro strip line feed U-shaped printed monopole antenna for Bluetooth/WI-MAX/WLAN communications systems is reported. The proposed monopole antenna has an eight shaped slot on the patch and an eight shaped ring structure in the ground with a metallic reflector beneath the ground plane. The CST Microwave Studio 2014 used for the simulation analysis of antennas while measurements performed by applying Vector Network Analyzer (R&S-ZVA 40). This radiating structure provides triple broad impedance bandwidths, i.e. 265MHz (in 2.280 GHz to 2.545 GHz frequency range), 116 MHz (in 2.660 GHz to 2.776 GHz frequency range) & 2.12 GHz (in 3.83 GHz to 5.956 GHz frequency range), wider 3dB axial ratio bandwidth 1.33 GHz (in 4.69GHz to 6.02GHz range), nearly flat gain (with maximum gain close to 5.56 (dBi) and good radiation patterns in the desired frequency range. This antenna may be a useful structure for 2.45GHz Bluetooth communication band as well as in WLAN & WI-MAX communications bands.

This paper illustrates the design and performance of microstrip feed elliptical shaped patch antenna having crossed shaped parasitic element. The overall size of antenna is 40 mm × 40 mm × 1.59 mm. For optimization of the performance of antenna, CST Microwave studio 2014 simulator is used while antenna is tested with available facilities under laboratory conditions. Proposed antenna provides triple impedance bandwidth extended between frequency ranges of 2.28‐2.62 GHz, 2.70‐3.96 GHz, and 5.1‐6.29 GHz with flat gain (close to 3‐5 dBi) in the desired frequency range. Good circular polarization conditions are realized at frequency 5.90 GHz for different sets of elevation and azimuth angles with maximum axial ratio bandwidth close to 600 MHz at the same frequency. The SAR values at desired frequencies are much lower than those for specified frequencies of modern communication systems. This antenna may be a useful structure for Wi‐Fi, WLAN, Wi‐MAX communication bands and lower and median UWB bands.

This paper exhibits the design and performance of a coplanar waveguide (CPW) fed triple notched band ultrawide band (UWB) antenna. Proposed prototype has two Ushaped slots on the patch and an inverted U slot in feed line with a metal reflector beneath the radiating element. Proposed structure renders wider impedance bandwidth extended between frequencies 2.71GHz to 12.92 GHz for VSWR < 2 with three rejection bands in the frequency ranges 3.456 to 3.988 GHz (WI-MAX IEEE 802.16), 5.27 to 6.032 GHz (WLAN IEEE 802.11 a/h/j/n) and 7.88 to 8.65 GHz (X-band down link satellite system) for VSWR > 2. The utmost simulated gain of proposed antenna with reflector is close to 9.9dBi at 7.4GHz. A sharp reduction observed in the efficiency values of the proposed structure at stop bands. Perhaps, this structure proved as a useful tool for various applications in modern communication systems including UWB.