Chatree Mahatthanajatuphat

A Rhombic Patch Monopole Antenna with Modified Minkowski Fractal Geometry for UMTS, WLAN, and Mobile WiMAX Application

This paper presents a rhombic patch monopole antenna applied with a technique of fractal geometry. The antenna has multiband operation in which the generator model, which is an initial model to create a fractal rhombic patch monopole, is inserted at each center side of a rhombic patch monopole antenna. Especially, a modified ground plane has been employed to improve input impedance bandwidth and high frequency radiation performance. The proposed antenna is designed and implemented to effectively support personal communication system (PCS 1.85–1.99 GHz), universal mobile telecommunication system (UMTS 1.92–2.17GHz), wireless local area network (WLAN), which usually operate in the 2.4 GHz (2.4–2.484 GHz) and 5.2/5.8 GHz (5.15–5.35 GHz/5.725–5.825GHz) bands, mobile worldwide interoperability for microwave access (Mobile WiMAX), and WiMAX, which operate in the 2.3/2.5 GHz (2.305– 2.360 GHz/2.5–2.69 GHz) and 5.5 GHz (5.25–5.85 GHz) bands. The radiation patterns of the proposed antennas are similar to an omnidirectional radiation pattern. The properties of the antenna such as return losses, radiation patterns and gain are determined via numerical simulation and measurement. Corresponding author: C. Mahatthanajatuphat (cmp@kmutnb.ac.th). 58 Mahatthanajatuphat et al.

A BIDIRECTIONAL MULTIBAND ANTENNA WITH MODIFIED FRACTAL SLOT FED BY CPW

This paper presents a multiband slot antenna with modifying fractal geometry fed by coplanar waveguide (CPW) transmission line. The presented antenna has been designed by modifying an inner fractal patch of the antenna to operate at multiple resonant frequencies, which efiectively supports the digital communication system (DCS 1.71{1.88GHz), worldwide interoperability for microwave access (WiMAX 3.30{3.80GHz), IMT advanced system or forth generation mobile communication system (3.40{4.2GHz), and wireless local area network (WLAN 5.15{ 5.35GHz). Manifestly, it has been found that the radiation patterns of the presented antenna are still similarly to the bidirectional radiation pattern at all operating frequencies. The properties of the antennas, for instance, return losses, radiation patterns and gain are determined via numerical simulation and measurement.

A COMPACT ULTRAWIDEBAND MONOPOLE ANTENNA WITH 5.5 GHZ NOTCHED BAND

This paper proposes a compact ultrawideband monopole antenna fed by CPW with a 5.5GHz notched band of WLAN/WiMAX systems. The antenna input section is designed by using a gradual curvature central line and ground planes for ultrawideband achievement. In order to reject the unwanted frequency of the existing WLAN/WiMAX band, the C-shaped slit with perimeter length of a half wavelength at center frequency of 5.5GHz has been embedded into the monopole patch. The designed antenna is completely implemented and measured for impedance bandwidth covering UWB range and stably performs omnidirectional pattern in xz plane from 3.1 to 10GHz. The proposed antenna could potentially minimize frequency interference in the WLAN/WiMAX bands.

A Double Square Loop Antenna with Modified Minkowski Fractal Geometry for Multiband Operation

A double square loop antenna with fractal geometry that supports for multiband operation is proposed. The antenna has multiband operation in that the generator model, which is an initial model to create a fractal loop antenna to operate at the first and second resonant frequencies, is inserted at each center side of a big square loop antenna. It also has a small square loop to operate at the third resonant frequency. The proposed antenna is implemented and shown to effectively support the global system for mobile communication (880-960 MHz), digital communication system (1710-1880MHz), personal communication system (1850-1990 MHz), universal mobile telecommunication system (1920-2170 MHz), and wireless local area network (2400-2483 MHz) bands. The radiation patterns of the proposed antenna are still similar to a bidirectional radiation pattern. The properties of the antenna such as return losses, radiation patterns and gain are determined via numerical simulation and measurement.

An elliptical dipole antenna with rectangular slot reflector for wideband applications

This paper presents an elliptical dipole antenna with rectangular slot reflector for wideband applications. The proposed antenna is designed on the FR4 substrate, resulting in low profile, high gain, and low cost. The antenna composes of an elliptical dipole and a slot rectangular reflector on the same plane. The proposed antenna has been analyzed and simulated by using the CST software package. In order to confirm the results, implementation and measurement of the antenna have been realized. The measured S11 < −10 dB covering a frequency range from 3 to 12 GHz with a relative bandwidth of 123.07 % and the pattern bandwidth from 3 to 6.5 GHz have been obtained. Also, the main lobe gain of 5.3 dB has been found.

A multiband fractal ring antenna fed by capacitive coupling

In this paper, a multiband fractal ring antenna fed by capacitive coupling is presented. The antenna is designed by generating the Minkowski fractal model on around the radiating ring antenna. Especially, the antenna is fed by using a technique of capacitive coupling to achieve the impedance bandwidth for supporting the operating frequency band of wireless communication systems, including 2.45 GHz, 3.50 GHz, and 5.20 GHz, respectively. The antenna covers the operating frequency band applications of the wireless communication standard, including IEEE 802.11 a/b/g (WLAN), IEEE 802.15.1a (Bluetooth), IEEE 802.16a (WiMAX), and IMT advanced system (4G mobile communication system), respectively. Moreover, the radiation pattern is improved to propagate the omnidirectional pattern at all of operating frequency bands, due to the fractal ring. The experimental and simulated results are presented and discussed.

Monopole antennas with modified Minkowski fractal geometry

This paper presents monopole antenna using the technique of square pulse Minkowski fractal geometry. The presented antenna is designed to cover at the operating frequency bands of 2.3, 2.45, 2.5, 5.2, 5.5, and 5.8 GHz, which is used in wireless local area network (WLAN; IEEE 802.11a, b, g) and mobile WiMAX (IEEE 802.16e) applications. Especially, the radiation patterns of antenna are still similar to omnidirectional at the operating frequencies. The properties of antenna such as return loss, radiation pattern and gain are determined via numerical simulation and measurement.

Study of CPW-fed slot antennas with fractal stubs

This paper studies CPW-fed slot antennas with fractal stubs. The S11 bandwidth of the antenna is affected by the fractal stub. It has been found that the antenna bandwidth will decrease when the iteration of fractal stub increases, which it will be opposite to the conventional fractal structures. In this study, fractal models with the 0, 1st, and 2nd iterations have been employed, resulting in the S11 bandwidths to be 121%, 115%, and 82%, respectively. Moreover, the radiation patterns of the presented antenna are still bi-directions and the average gains of antenna are above 2 dBi for all of fractal stub iterations. Results indicate an impedance bandwidth covering the band for 3G, WLAN, and WiMAX.

A Compact UWB Antenna with a Quarter-Wavelength Strip in a Rectangular Slot for 5.5 GHz Band Notch

The limitation of the electromagnetic interferences (EMIs) caused by UWB radiating sources into WLAN/WiMAX communication systems operating in the frequency band located around 5.5 GHz requires the adoption of appropriate design features. To this purpose, a notch filter integrated into an UWB antenna, which is able to ensure a better electrical insulation between the two mentioned communication systems with respect to that already presented by the authors Moeikham et al. (2011), is proposed in this paper. The proposed filter, consisting in a rectangular slot including a quarter-wavelength strip integrated on the lower inner edge of the UWB radiating patch, is capable of reducing the energy emission in the frequency range between 5.1 and 5.75 GHz resulting in lower EMIs with sensible electronic equipments working in this frequency band. The antenna structure has no need to be tuned after inserting the rectangle slot with a quarter-wavelength strip. The proposed antenna has potential to minimize the EMIs at a frequency range from 5.1 to 5.75 GHz. The radiation patterns are given nearly omnidirectional in plane and likely bidirectional in plane at all frequencies by the proposed antenna. Therefore, this antenna is suitable to apply for various UWB applications.

Series-fed microstrip array antennas using a fractal structure with NP generator model

This paper presents microstrip array antennas applied to a technique of fractal geometry. The presented antenna is designed at the operation frequency 2.45 GHz, which is used in application of wireless local area network. The presented array antennas have equal space between centers of each element, which is 0.5 lambdao. It has been found that dimension and back lobes of the presented fractal array antenna are reduced comparing with the array of normal square patch array antenna. Obviously, the radiation patterns of the presented array antennas are still similarly to the normal square patch array antenna. The properties of the antennas for instance return losses, radiation patterns and gain are determined via numerical simulation and measurement.