M. A. Jamlos

A Novel Compact Tree-Design Antenna (NCTA) with High Gain Enhancement for UWB Application

In this paper, a novel compact tree-design antenna (NCTA) for ultra-wideband (UWB) application with high gain and impedance matching improvement is analyzed and presented. The novel antenna is composed of a single centered circle connected to seven outer circles via three bridges with partial ground plane execution. Instead of functioning as filters, these seven circles play a major role in producing UWBs frequency resonant of 3.3 to 10.8 GHz with a minimum reflection coefficient of −10 dB (|S 11| < −10 dB). Furthermore, this compact antenna structure (38 mm × 38 mm) which is fed by the microstrip line generates a high gain of up to 5.5 dBi. Moreover, the proposed tree-design antenna possesses a linear polarization with a proficient omni-directional radiation pattern at 3.5 and 5 GHz and a divisive radiation pattern at 7.5 and 10 GHz. The parametric study performed for the purpose of antenna compaction is emphasized in the details of this research. The numerical and measurement results exhibit the success of the antennas performance. The attainable NCTA is sufficiently competent to be an initial structure consideration for the future Multi-Input Multi-Output (MIMO) development.

A fabrication of intelligent spiral reconfigurable beam forming antenna for 2.35-2.39 Ghz applications and path loss measurements

A reconflgurable beam forming antenna prototype using a spiral feed line is proposed in this paper. The presented antenna is integrated with PIN diode switches at a speciflc location of spiral feed line. It is discovered that the beam steering ability is greatly in∞uenced by the spiral arm feed network. Four PIN diode switches have been incorporated at four difierent arms of spiral feed line to realize a beam forming ability. The intelligence behaviour of this antenna is conferred when the switches are connected to programmable intelligent computer (PIC) microcontroller. Certain conflgurations of PIC allow the antennas radiation patterns to be adaptively changed within 0.01ms. Therefore, the proposed antenna is capable of electronically forming the beam up to four difierent angles of +176 - , +10 - , i1 - and i12 - . This antenna is small in size with 100mm by 100mm of substrate dimension. In this research, the site fleld antenna performance relying on the received signal strength (RSS) testing is tested intensively in Universiti Malaysia Perlis with varied distant points of line-of- sight (LOS) and non-line-of-sight (NLOS) propagation. With good simulation and measurement results, this antenna could be a promising candidate to be installed in applications such as a smart antenna system, cognitive radio, WiMAX and long term evolution (LTE).

High performance of coaxial feed UWB antenna for human brain microwave imaging

A 4×1 array Ultra wide band (UWB) antenna coaxially feed is proposed in this paper. Four copper circular patches are appropriately connected using quarter-wavelength transformer transmission line. Introduction of copper parasitic element and copper partial ground technique are applied in this proposed antenna. Taconic associated with 2.2 dielectric constant is utilized as the antenna substrate. The proposed antenna recorded reflection coefficient less than -10dB started from 2.6 GHz until 13.1 GHz which fulfilling the requirement of UWB. Dimensions of 80 mm × 45 mm and maximum gain of 12.12 dB made it as small and high gain UWB antenna. The antenna exhibit excellent radiation efficiency of more than 90% over the whole operated frequency and has 83% of usable fractional bandwidth. The proposed antenna performance finds it very suitable to be applied in human brain microwave imaging.

An optimum quarter-wave impedance matching feedline for circular UWB array antenna with high gain performance

The goal of this paper is to designed ultra-wide band (UWB) array antenna for biomedical application. The array arrangement is introduced to improve the performance of the antenna in terms of return loss, gain, bandwidth, and directivity. In this paper, a four-element antenna array is presented. The antenna array is composed of quarter wave feed network along with four-identical circular patch antenna elements designed and simulated using Computer Simulation Tool (CST) Microwave Environment software. The performance of the designed array antenna evaluated in term of return loss, Voltage Standing Wave Ratio (VSWR), bandwidth, radiation pattern, directivity and gain. The array elements and its feed network are properly designed to have a very wide useful band and high gain antenna against frequency. Introduction of unique mitered structures along the feedline and low right side feed realize UWB array antenna with high gain. The simulation result of return loss shown that the operating bandwidth less than -10 dB is start from 4.5 GHz until more than 20 GHz at gain range of 4.2 dB until more than 8 dB at VSWR less than 2. The antenna has an excellent averaged directivity of 7 dBi and a widespread functioned fractional bandwidth of more than 129%. Simulated result shows that the array has a peak gain of more than 8 dB at 9 GHz. These features lead the UWB antenna array appropriate for microwave imaging purposes. The antenna is fabricated on the low cost FR-4 substrate with dielectric constant of 4.7 and thickness of 1.6 mm. Less complicated fabrication methods is possible due to the feeding network placement is on the same level with the antenna patch elements.

MIMO 2×2 RHCP array antenna for point-to-point communication

A high gain 5.8 GHz multiple input multiple output (MIMO) 2×2 Array antenna with dimension of 58 × 110 mm2 is proposed in this paper. The proposed design is composed of two sets of four elements antenna array. Each element is constructed from four truncated arrays radiating elements which capable to achieve circular polarized capability. The antenna is fed by two coaxial feeds with full ground plane and etched on Taconic TLY-5 substrate with 2.2 and 1.575 mm of dielectric constant and thickness respectively. An array antenna concept is used in this design to enhance absolute gain of up to 14.26 dB and has a reflection coefficient of -28.2dB. The combination of two-port array antenna will enhance the gain of transmitter to achieve a last mile performance while simultaneously avoiding significant attenuated signals under adverse atmospheric conditions. This paper focusing more on MIMO system that are used in 5.8 GHz applications.

Circular polarized phased shift 90° MIMO array antenna for 5.8 GHz application

In this paper, a circular polarized multiple input multiple output (CP-MIMO) 2×2 array structure coupled with phased shift 90° feeding line and high gain performance are presented. The presented antenna is designed to operate in particular frequency of 5.8 GHz with circular polarization. The presented antenna combine three methods into a single antenna and excited by a two of 50 Ω coaxial probe feeds. It is a combination of MIMO system which have two port coaxial feed and each port are designed using 2×2 array structure. Each array consists of four circular radiating elements which each element constructs with 90° physical phased shift feeding line to achieve circular polarized capability. The CP-MIMO array antenna is etched on FR4 substrate with 4.7 and 1.6 mm of dielectric constant and thickness respectively.