VHF adaptive antenna using a rear defogger

This thesis presented the design of an adaptive bearnforming antenna using a rear defogger. The main purpose of this project is to develop the vehicular adaptive antenna for VHF band, which does not require the installation space, does not spoil the industrial design, has low cost and low power consumption. In land communication, there is no clear line of sight between transmitter and receiver. The transmitted signal might be reflected, refracted because of the building or terrain. The receiver might receive a delayed, or reflected signal instead of the original signal. Adaptive antenna is the best candidate to mitigate the multipath fading effects. However, for VHF band, conventional adaptive antenna has a drawback of a large aperture size. Therefore, in this paper a rear defogger is proposed as an aperture to overcome the size problem of using a conventional adaptive antenna. A rear defogger of a vehicle can be used as an aperture, '7-3 and in order to make it compatible with ESPAR antenna, several ports have been 1 1, provided. One port is used as an active port or output port, while other ports are connected to the variable reactor. Downhill simplex method is used as an algorithm to form the adaptive beam for the proposed antenna. This algorithm is maximized the correlation coefficients. Simplex method has been chosen because it has several advantages. Simplex method has a fast convergence time, robust beamforming, and it can be used for multi-dimensional optimization. There are several steps in simplex method for optimization; reflection, expansion, contraction, and multiple contractions. IE3D software is used to model the defogger with the car and from the IE3D results it shows that the defogger can be used as an adaptive antenna because it has low voltage standing wave ratio (VSWR) to make it operate as an antenna, low spatial cross correlation (SCC) for better diversity and has high coupling between port (CBP) for better capability of beamforming. In the analysis, the VSWR is lower than 3, SCC is lower than 0.5, and the CBP is between -6 dB to -10 dB. For numerical simulation, MATLAB is used to make a program for simplex method. From the simulation results, it shows that almost 80 % of the signals have signal to interference noise ratio (SINR) greater than 20 dB. Besides that, null is performed for incoming interference and remained high gain for the desired signal. A Rear defogger is made from heating wire, therefore it is necessary to confirm the effects of the resistivity to the antenna's performance. The effects of the resistivity has been confirm through IE3D simulator and MATLAB programming by comparing it to the copper wire. From IE3D simulator, comparison has been made for VSWR, SCC, and CBP for both resistive and copper wire. The results show that the values of VSWR, SCC, and CBP for copper and resistive wires are nearly same. A statistical analysis has been carried out for copper and resistive wire, and the analysis show that the performance of the resistive wire is slightly decrease compared to copper wire. However, the different is very small, plus the resistive wire has more than 80% of the signal has SINR greater than 20 dB. The beam pattern is controlled by a varactor circuit. The varactor circuit is connected to the three passive elements. The reactance range is limited from - j300Q to j3000 in the simulation, consider manufacturing. It is difficult to manufacture a large range of reactance. The reactance value is different for each incoming DOAs. Measurement has been conducted in anechoic chambers for adaptive beamforming. It shows that after perform beamfonning, null is performed for incoming interference, improved VSWR, BER and SINR over the bandwidth. The proposed antenna has a fast convergence times, the convergence time is less than 50 ms and the iteration number is less than 70. Measurement in Rayleigh fading environment also been conducted, it shows that by applying the beamforming the BER is improved. The experiment was conducted for 473 ' * ' , xi MHz and 900 MHz for horizontal (co-polarization) and vertical (cross-polarization). For both co-polarization and cross-polarization, BER show an improvemen

Electronically steerable antenna for WLAN application

In wireless communication systems, interference becomes a major problem in limiting the quality of the transmitted and received signals. A common problem in wireless communications is to eliminate the interference signal that is mixed with the original signal. Thus, adaptive beamforming is proposed to eliminate the interference signal. This paper presents an adaptive antenna using a slotted patch antenna for WLANs operated at 2.4 GHz. A reactively steerable antenna concept has been applied. A downhill simplex algorithm is used to maximize the cost function. The radiation pattern of the antenna is controlled by the reactance value connected to each port. From numerical simulation, null is performed for the incoming interference

Ultra-Wideband Monostatic Antenna for behind the Wall Detection

This article introduces an ultra-wideband (UWB) shifted arc antenna, designed using Rogers RT-5880 Duroid substrate for the human detection behind the wall. The frequency for this proposed antenna ranges from 2.8 - 15.6 GHz with the gain of around 6.05 dB. A high gain for antenna has been achieved by the implementation of defected ground structure (DGS) method to make it a suitable configuration for through wall detection applications. For the verification of through wall detection configuration, a simulation-based experiment using ground penetrating radar (GPR) technology has been conducted. The results showed that proposed single antenna can act as a monostatic transceiver in order to detect human skin behind the concrete wall. Later, the reflections received from the target have been analyzed to detect and identify the antenna, wall and target for distance calculation

Wideband Sierpinski carpet monopole antenna

This paper described the design and fabrication of the fractal Sierpenksi carpet monopole antenna. The properties of antennas such as bandwidth and radiation pattern have been investigated. Wide bandwidth with input return loss of -10 dB has been achieved from 1 GHz to 10 GHz using this fractal antenna. The radiation patterns have been investigated at 2.73 GHz and 4.29 GHz. The cross polar isolation is in the range of -20 dB for both frequencies. The radiation pattern is in the direction of the main lobe

Design of wideband Rotman lens for wireless applications

An electrically steerable beam is an essential standard in the recent wireless application in order to increase the gain and reduce the interference. However, high performance of amplitude besides low phase error difficult to achieve without indicators are used to set lens parameters to desired optimum performance design level. In this paper, the introduced microstrip lens has examined a comprehensive explanation for parameters and indications amid a full wave structure methodology. Further, Phase and energy coupling between excited ports and received ports besides phase error and its relation with the lens parameters design are explained in detailed.  A wideband beamforming network based on a printed microstrip Rotman lens with a ±26o scanning angle was designed in this study. The designed lens operates at 2.45 GHz with 592 MHz bandwidth. The lens consists of five switchable ports (input ports) with four output ports that connected to the microstrip patch antennas. The five switchable ports were used to realize the scanning beams angle in the azimuth plane.  The proposed model is simulated by CST Microwave Studio and fabricated on FR-4 with 1.565 mm thickness and 4.2 permittivity.  A good agreement between simulation and measurement results were achieved

A compact size microstrip five poles hairpin band-pass filter using three-layers structure for Ku-band satellites application

This paper presents a reduced size microstrip five poles hairpin band-pass filter using three-layers structure for Ku-band satellites application. The three-layers structure shows a substantially reduced filter size and enlarged bandwidth. The filter has been designed based on five-pole resonators at 12.475 GHz and bandwidth of 550 MHz. This filter is designed on Rogers RO3003 substrate having relative permittivity (εr) of 3. The proposed band-pass filter has been designed with the help of Computer Simulation Technology (CST) software. Comparison analyses between the simulated insertion loss and reflection coefficient of RO3003 and FR4 substrates have been carried out in order to show the efficiency of the proposed filter design. Based on the obtained results, the proposed filter design achieves significant filter size reduction compared to other band-pass filters

A compact size microstrip five poles hairpin band-pass filter using three-layers structure for Ku-band satellites application

This paper presents a reduced size microstrip five poles hairpin band-pass filter using three-layers structure for Ku-band satellites application. The three-layers structure shows a substantially reduced filter size and enlarged bandwidth. The filter has been designed based on five-pole resonators at 12.475 GHz and bandwidth of 550 MHz. This filter is designed on Rogers RO3003 substrate having relative permittivity (εr) of 3. The proposed band-pass filter has been designed with the help of Computer Simulation Technology (CST) software. Comparison analyses between the simulated insertion loss and reflection coefficient of RO3003 and FR4 substrates have been carried out in order to show the efficiency of the proposed filter design. Based on the obtained results, the proposed filter design achieves significant filter size reduction compared to other band-pass filters

Maximising system throughput in wireless powered sub-6 GHz and millimetre-wave 5G heterogeneous networks

Millimetre wave (mm-Wave) bands and sub-6 GHz are key technologies in solving the spectrum critical situation in the fifth generation (5G) wireless networks in achieving high throughput with low transmission power. This paper studies the performance of dense small cells that involve a millimetre wave (mm-Wave) band and sub-6 GHz that operate in high frequency to support massive multiple-input-multiple-output systems (MIMO). In this paper, we analyse the propagation path loss and wireless powered transfer for a 5G wireless cellular system from both macro cells and femtocells in the sub-6 GHz (µWave) and mm-Wave tiers. This paper also analyses the tier heterogeneous in downlink for both mm-Wave and sub-6 GHz. It further proposes a novel distributed power to mitigate the inter-beam interference directors and achieve high throughput under game theory-based power constraints across the sub-6 GHz and mm-Wave interfaces. From the simulation results, the proposed distributed powers in femtocell suppresses inter-beam interference by minimising path loss to active users (UEs) and provides substantial power saving by controlling the distributed power algorithm to achieve high throughput