In the near future, the development of the personal communication devices will aim to provide image, DMB (Digital Multimedia Broadcasting), video telephony, speech and data communications at any time-any where around the world using the WLANs (Wireless Local Area Networks). Rapid advances of various WLAN protocols have sparked the requirements for miniaturized multi-band antennas with suitable frequency bands appropriate for the Wi-Fi (IEEE 802.11 standard) and mobile WiMAX (IEEE 802.16e-2005 standard) applications. The demand for compact size, light weight and low cost antennas has increased in the recent years with the widespread deployment of wireless communications, like the wireless local area networks (WLAN). In order to satisfy the IEEE 802.11 WLAN standards in the 2.4 GHz (2400-2484 MHz) specified by IEEE 802.11b/g /5.2 GHz (5150-5350 MHz)/5.8 GHz (5725-5825 MHz)specied by IEEE 802.11a operating bands and the worldwide inter operability for microwave access (WiMAX) 2.5/3.5/5.5 GHz(2500-2690/3400-3690/5250-5850 MHz) bands, multi-band antennas with low cost, compact size, easy fabrication and higher performance are required.
We investigated two antenna structures suitable for WLAN standards. The first is a wide band probe fed inverted slotted micro strip patch antenna, which provides a enhancement in bandwidth. We tried out various structures including a trapezoidal structure,e-slot structure, U shaped structure L shaped structure and E shaped structure. Among these, E shaped structure provides an enhanced bandwidth. A detailed parameter study of the structure by varying its physical dimension are also done to optimize the dimensions for maximum bandwidth covering WLAN standards. The next structure is a E-shape and U-shape Patch Antenna, which resonates at multiple frequencies which satisfies both WLAN and Wi-Max standards. The structure we used here is a connected E & U geometry with a notch and triangular cut on each edge. Both structures provided good performance. The software we used to simulate these antenna structures is High Frequency Structure Simulator (HFSS) version-11. HFSS is an interactive software package for calculating the electromagnetic behavior of a structure. The software includes post-processing commands for analyzing this behavior in detail.
Using HFSS, we can compute:
- Basic electromagnetic field quantities and, for open boundary problems, radiated near and far fields.
- Characteristic port impedance and propagation constants.
- Generalized S-parameters and S-parameters re-normalized to specific port impedance.
- The eigen modes, or resonances, of a structure.
The report is organized in to four sections. The first section provides a detailed survey of the wide band antennas and the double frequency antennas and is reported in the literature. The next chapter has two sections each part discussing the structures and their performance. Then results and discussions of each structure is presented as third chapter. Last chapter presents the conclusion of our study.
Please go through the attached project report more info.