The Study of Reconfigurable Antennas and Associated Circuitry

This research focuses on the design of pattern reconfigurable antennas and the associated circuitry. The proposed pattern reconfigurable antenna designs benefit from advantages such as maximum pattern diversity and optimum switching circuits to realise 5G reconfigurable antennas. Whereas MIMO based solutions can provide increased channel capacity, they demand high computational capability and power consumption due to multiple channel processing. This prevents their use in many applications most notably in the Internet of Things where power consumption is of key importance. A switched-beam diversity allows an energy-efficient solution improving the link budget even for small low-cost battery operated IoT/sensor network applications. The main focus of the antenna reconfiguration in this work is for switched-beam diversity. The fundamental switching elements are discussed including basic PIN diode circuits. Techniques to switch the antenna element in the feed or shorting the antenna element to the ground plane are presented. A back-to-back microstrip patch antenna with two hemispherical switchable patterns is proposed. The patch elements on a common ground plane, are switched with a single-pole double-throw PIN diode circuit. Switching the feed selects either of two identical oppositely oriented radiation patterns for maximum diversity in one plane. The identical design of the antenna elements provides similar performance control of frequency and radiation pattern in different states. This antenna provides a simple solution to cross-layer PIN diode circuit designs. A mirrored structure study provides an understanding of performance control for different switching states. A printed inverted-F antenna is presented for monopole reconfigurable antenna design. The proposed low-profile antenna consists of one main radiator and one parasitic element. By shorting the parasitic element to the ground plane using only one PIN diode, the antenna is capable of switching both the pattern and polarisation across the full bandwidth. The switched orthogonal pattern provides the maximum spatial pattern diversity and is realised using a simple structure. Then, a dual-stub coplanar Vivaldi antenna with a parasitic element is presented for the 5G mm-Wave band. The use of a dual-stub coupled between the parasitic element and two tapered slots is researched. The parasitic element shape and size is optimised to increase the realised gain. A bandpass coupled line filter is used for frequency selective features. The use of slits on the outer edge of the ground plane provides a greater maximum gain. This integrated filtenna offers lower insertion loss than the commercial DC blocks. The UWB antenna with an integrated filter can be used for harmonic suppression. The influence of the integrated filter circuit close to the antenna geometry informs the design of PIN diode circuit switching and power supply in the 5G band. Based on the filter design in the mm-Wave band, a method of designing a feasible DC power supply for the PIN diode in the mm-Wave band is studied. A printed Yagi-Uda antenna array is integrated with switching circuitry to realise a switched 180° hemispheres radiation pattern. The antenna realises a maximum diversity in one plane. The study offers the possibility to use PIN diodes in the mm-Wave band for reconfigurable antenna designs. For the presented antennas, key geometric parameters are discussed for improved understanding of the trade-offs in radiation pattern/beamwidth and gain control for reconfigurable antenna applications

Pattern Reconfigurable Back-to-Back Microstrip Patch Antenna

A back-to- back microstrip patch antenna with a switchable pattern is proposed for WLAN applications. The patch elements, printed on FR-4 substrates with a common ground plane, are switched with a single-pole double-throw PIN diode circuit. Switching the feed selects either of two identical radiation patterns in the opposing hemispheres for spatial diversity that would benefit a distributed network

Study of Mm-wave Microstrip Patch Array on Curved Substrate

A millimetre wave rectangular microstrip patch antenna array for fifth generation communications (5G) applications is presented. With the increase in demand for high data rates and capacity, there is a need to include mm-Wave frequencies for 5G. The 4×2 patch array is simulated and fabricated on a Rogers RT/Duroid 5880 substrate with a thickness of 0.25 mm. The effects of bending the substrate on the antenna performance are also presented. The experimental results show a fractional bandwidth and gain of more than 3% and 16.1 dBi, respectively

A Dual Band 450LTE/GSM900 PIFA for Portable Devices

A dual band PIFA antenna for portable devices is presented. It operates in the 450 LTE (449 − 461 MHz) and GSM 900 (876 – 922 MHz) frequency bands. The proposed antenna which has a very compact size of 7 (0.01λ0) × 7 × 70 (0.1λ0) mm3 and is suitable to integrate in small envelopes, consists of two branches and a metallic patch. The low cost and easily fabricated antenna offers high total efficiency and gain in both bands. Measured and simulated results are provided

A Simple Polarization Reconfigurable Printed Monopole Antenna

A simple polarization reconfigurable printed monopole antenna is proposed for wireless applications. Conducting strips are used to connect to the ground plane providing the necessary additional modes for circular-polarization. Linear-polarization, right hand or left hand circular-polarization can be realized using only two PIN diodes, which connect to the ground plane, minimizing their effect on radiation characteristics. The mechanism is described, and key antenna parameters are studied and optimized. The antenna is prototyped and tested for all polarization configurations

Amorphous Silicon Solar Vivaldi Antenna

An ultra-wideband solar Vivaldi antenna is proposed. Cut from amorphous silicon cells, it maintains a peak power at 4.25 V which overcomes a need for lossy power management components. The wireless communications device can yield solar energy or function as a rectenna for dual-source energy harvesting. The solar Vivaldi performs with 0.5 - 2.8 dBi gain from 0.95 - 2.45 GHz and in rectenna mode, it covers three bands for wireless energy scavenging

A coplanar vivaldi antenna with integrated filter for Ka-band

A new design approach of a dual-stub coplanar Vivaldi antenna with integrated filter is presented. The dual-stub excites coupling between a parasitic elliptical element and tapered slots. The dimensions of the parasitic element are studied and optimized for wide beamwidth. The band pass filter is used for sub harmonic suppression and pattern shaping

Dual-Stub Ka-Band Vivaldi Antenna with Integrated Bandpass Filter

A dual-stub coplanar Vivaldi antenna with a parasitic element is presented. The dual-stub is coupled between the parasitic element and two tapered slots. The parasitic element shape and size is optimised. The use of slits on the outer edge of the ground plane is shown to provide control of beamwidth and maximum gain. A bandpass filter is used for performance control and sub-harmonic suppression

Ka-band Vivaldi Antenna with Novel Core Element for High-Gain

A high gain Vivaldi antenna employing an integrated core element is proposed. The maximum antenna gain is 16.9 dBi and it performs better than 14 dBi over the complete Ka (24 - 40 GHz) band. The design methodology, excitation arrangement and field distribution features are described

Ka-band Planar Vivaldi Antenna with a Core for High-Gain

A planar Vivaldi antenna structure with a core element is proposed for high gain. Techniques to achieve a significant gain improvement over the full Ka (24-40 GHz) band are implemented; including a frequency-independent excitation method, the introduction of logarithmic ripple on the lateral edges and enclosing the antenna in a dielectric material