Syed S. Jehangir

A comparison between two different excitations for Quasi-Yagi antennas

A wide-band Quasi-Yagi antenna with loop excitation and a performance comparison between a dipole based Quasi-Yagi are presented, targeting the 5.8 GHz band. The proposed Quasi-Yagi antenna with loop excitation has a very wide measured bandwidth of 1.43 GHz which covers from 5.574-7 GHz. It has a very high Front-to-back ratio (FBR) of 18.7 dB with a ground size of 11 mm. The proposed antenna has a gain of 4.7 dBi, overall size of 60 × 60 mm2, and efficiency of 93%. The dipole based Quasi-Yagi antenna has a minimum measured bandwidth of 963 MHz and minimum FBR of 12 dB with a ground size of 18.6 mm. It has a gain of 3.56 dBi, overall size of 30 × 25 mm2, and efficiency of 73%. The superior efficiency, bandwidth, gain and FBR performance of the loop excited one comes at the cost of 79% larger size.

A miniaturized UWB bi-planar yagi-like antenna

A novel Ultra-wideband (UWB) Yagi-like antenna is proposed targeting the 5 GHz WLAN bands. The bi-planar design relies on the technique of using a half loop ring on each side of the substrate which provides a miniaturization of 45%, a minimum measured −10 dB percent bandwidth of 43.3%, and a high gain of 6.43 dBi. The total board size of the miniaturized model is 50 × 40 × 0.76 mm3. The proposed Yagi-like antenna has directional radiation characteristics with a very high front-to-back ratio (FBR) of more than 19 dB using a small ground plane size of 11×40 mm2, and directivity of around 7 dB using a single director element. The efficiency of the antenna is 92%.

A miniaturized multi-wideband quasi-yagi antenna with rectangular loop excitation

A highly directional multi-wideband Quasi-Yagi antenna is presented based on rectangular loop excitation. A miniaturization of 64% is achieved using a simple loop meandering technique and a small ground plane size. The overall size of the antenna is 55 × 60 × 0.76 mm3. The proposed antenna system covers the Telemetry L-band and several celluar and WLAN bands. It has a minimum measured −6 dB bandwidth of 376 MHz in the desired band centered at 2 GHz and a measured bandwidth of at least 200 MHz in rest of the bands. A defected ground structure (DGS) is employed to achieve a very high front-to-back ratio of 20 dB using a small ground plane size. The proposed antenna has very low cross-polarization in the end-fire direction. It has a gain of 5.4 dBi and an efficiency of 94%.

A miniaturized dual wide-band loop excited quasi-yagi antenna using a defected ground structure

A dual wide-band Quasi-Yagi antenna with loop excitation and its 52% miniaturized model using novel defected ground structure (DGS) is presented, targeting the 2 GHz band. The proposed dual wide-band antenna system has a measured bandwidth of around 1 GHz in both bands that cover 1.45-2.55 GHz and 3.707-4.71 GHz bands including GPS, GSM/EDGE, UMTS/HSDPA, Bluetooth, Wi-Fi, and WiMAX bands. The miniaturized version has a measured bandwidth of 1.5 GHz in the lower band while 620 MHz in the upper band. The size of the antenna without DGS is 78×117.5 mm2. It has a gain of 5.94 dBi, directivity of 6.21 dB, and front-to-back ratio (FBR) of 9.5 dB. The miniaturized antenna has a size of 55×80 mm2. It has a gain of 4.23 dBi, directivity of 4.33 dB, and FBR of 8.5 dB. Both designs have efficiencies around 92%. The superior performance of the antenna without DGS in terms of FBR, gain, and directivity, comes at the cost of 52% larger size.

A 4-element dual wideband circular Yagi MIMO antenna system with loop excitation

A 4-element dual-band Circular Yagi based multiple-input-multiple-output (MIMO) antenna system with loop excitation is presented. It has a very wide-bandwidth of 1 GHz in both bands. The lower band covers from 1.45-2.55 GHz while the upper band covers from 3.707-4.71 GHz. This antenna is highly directional with front-to-back ratio (FBR) of 13.8 dB, gain of 6.6 dB and directivity of 7 dB. The proposed antenna shows good MIMO performance in terms of isolation and correlation. It has a minimum isolation of 23 dB across both bands. Due to its geometry configuration, the radiation patterns are orthogonal to each other and hence it has very low correlation coefficient values not exceeding than 0.1338. The size of the single antenna is 78 × 117.5 mm2 while overall size is 263 × 263 mm2.