M. N. Md Tan

A Beam Steering Radial Line Slot Array (RLSA) Antenna with Reconfigurable Operating Frequency

A beam steering radial line slot array (RLSA) antenna with reconfigurable operating frequency is proposed in this paper. The RLSA antenna is fed by an aperture coupled structure, which incorporates PIN diode switches that are integrated with the feed line. It is found that the beam steering ability and reconfigurable operating frequency are greatly influenced by the spiral and radius of feed line respectively. The activation of certain PIN diode switches configuration would then determine the beam steered angle and the frequency of operation. This novel antenna design is capable of steering its radiated beam to four different angles; 0°/360°, 90°, 180°, and 270°. Furthermore, the proposed antenna can be configured to operate from a single centre frequency, up to four operating centre frequencies concurrently, at each steered beam direction. The four frequencies are 2.3 GHz, 2.6 GHz, 2.9 GHz and 3.3 GHz. This antenna is a promising candidate to be installed for a smart antenna system, cognitive radio, radar or direction finding applications in the future.

A reconfigurable radial line slot array (RLSA) antenna for beam shape and broadside application

A reconfigurable beam shape and broadside radiation pattern microstrip antenna is introduced in this paper. The antennas radiating surface is designed using a radial line slot array (RLSA) arrangement, which is fed from an aperture coupled structure. This novel feeding structure for an RLSA antenna incorporates PIN diode switches which are integrated with the feed line structure to enable the various outcomes of the radiation patterns. The circular arrangement of slots at the radiating surface contributes to the reduction in size of the proposed antenna compared to conventional microstrip antenna that can yield the same antenna gain. The proposed antenna design operates at 2.3 GHz frequency band and has a maximum gain of 14.64 dB. It also produces a broadside radiation pattern with a wider beamwidth covering from −85° to 85° compared to the conventional microstrip antenna which could only cover from −50° to 50°. The proposed antenna has an enormous potential for point-to-point and point-to-multipoint communication, WiMAX, and radar application.

A Reconfigurable Planar Antenna Array (RPAA) with back lobe reduction

A novel structure of Reconfigurable Planar Antenna Array (RPAA) added with a microwave absorber is designed. This antenna is consists of two elements structure, which are the 16-element microstrip rectangular patch antenna structures (top structure) and the separated feed line structure (bottom structure). The unique property of this antenna design is that instead of fabricating all together in the same plane, the antennas feeding network is separated from the antenna radiating elements (the patches) by an air gap distance. This allows reducing spurious effects from the feed line. This antenna is integrated with RF switches to produce the scanning beam pattern to desired direction. This can be done by controlling the switch state to either on or off mode. The additional material was proposed involves placing a microwave absorber material such as ECCOSORB@ (Emersion & Cuming Microwave Products, Inc., Randolph, and Mass) at the back of the top substrate. The ECCOSORB is useful for suppression of unwanted radiated field and thus improved the back lobe pattern at an average of 10 dB. The simulated results are presented to demonstrate the excellent performance of this antenna.

Reconfigurable linear array antenna with beam shaping at 5.8GHz

In this paper, experimental data was demonstrated the concepts of reconfigurable number of elements that produced broad beam and narrow beam radiating pattern characteristic. Using modified WPD in the antenna structure, produced better performance in term of return loss characteristic. This research has taken advantage of the flexibility of the number of element technique by applying it to the problem of reconfigurable multiple beam array combination. The reconfigurable dual-beam antenna pattern at fixed frequencies across the entire 5.7-5.9 GHz band was presented in this paper with excellent radiation patterns.

Frequency reconfigurable quasi-Yagi microstrip antenna with beam shaping for WiMAX application

This paper presents a frequency reconfigurable quasi-Yagi microstrip antenna with beam shaping for WiMAX application by using a folded dipole as a driven element. The reconfigurability of this antenna can be achieved by varying length of driven element. The usage of PIN diodes which act as switches will help to vary the length of driven element. This microstrip antenna has use quarter-wave matched T-junction power divider to match the impedances between feed line and driven element. Furthermore, this quasi-Yagi microstrip antenna was originally designed using CST Microwave Studio for operation in 5.8GHz frequency band. However, by changing the driven element length, this quasi-Yagi microstrip antenna can operate at differ frequency and differ directions. In addition, this reconfigurable quasi-Yagi microstrip antenna with switching has been fabricated and experimental results are provided in this paper.

Reconfigurable beam shaping antenna with Wilkinson Power Divider at 5.8GHz

This paper presents a reconfigurable multiple element microstrip rectangular linear array antenna integrated with radio frequency (RF) switches. The corporate feed design concept is used to excite the linear array antenna that consists of 8 elements of rectangular patches at 5.8 GHz. Two PIN diode switches were deployed at the feeding line to activate the two arrays of patches that is located on the left and right side of the antenna structure. The behavior of the reconfigurable multiple element linear antenna array system has been investigated with respect to beam shaping characteristic. The comparisons of the performance between two structures, with Wilkinson power divider (WPD) and without WPD are discussed in this paper. Two different beam patterns were achieved through the reconfigurable antenna at different number of elements design that incorporates with PIN diode switches and modified WPD concept. The simulations and the measurement results for 4 and 8 elements array antenna structure are presented.

Smart antenna:Weight calculation and side-lobe reduction by unequal spacing technique

This paper is divided into two parts. The first part presents the study of smart antenna beamforming where a single beam is shaped by weighting and summing the antenna outputs. In order to calculate the weight of the array elements, the conventional beam-former (known as delay and sum) has been chosen. Matlab software is used to calculate the weights, and to obtain the array factor of 8 elements linear array antenna. The second part illustrates that, the side-lobe can be reduced by using unequal spacing technique, but the number of elements is remained unchanged. The comparison between symmetric and asymmetric arrangement for unequal spacing is also presented. The results show that by using the symmetrical arrangement, the side-lobe obtained is much better than asymmetrical arrangement. In fact, the side-lobe produced by asymmetrical arrangement is worse than the equal arrangement.

A reconfigurable aperture planar array antenna based on separated feeding network

In this paper an innovative reconfigurable aperture antenna in a planar array of small patches have been investigated in order to steer the radiation pattern by changing the switches that are ON and OFF mode. The basic concept of the antenna is verified by comparing theoretical results with measurements for configurations in which the PIN diode switches are simply integrated with the feeding line. The versatility of this designed antenna is using a separated feeding network plane interconnected by a small coaxial connector. The simulation results for the antenna are then compared with measurements is used to steer the beam pattern of the antenna. Observed from the results, it is demonstrated that the steering beam pattern at various direction with good impendence matching is be achieved. The antenna was fabricated and measured and the results for the return losses show reasonable agreement.