Frequency Reconfigurable Antenna System Research Articles

A quad-port multiple-input-multiple-output system for underlay or interweave cognitive radio

<span lang="EN-US">This paper presents a four-element frequency reconfigurable antenna system that is novel in terms of gathering both underlay and interweave cognitive radio in a single multiple input, multiple output (MIMO) design. Built on a 50×38×0.8 mm3 Rogers RT/Duroid 5880 substrate, this system is constructed of two scanning elements to sense ultra-wide band (UWB) with controllable band notching capabilities and two elements act as communication antennas. Eighteen MIMO modes can be provided depending on the state of the five positive-intrinsic-negative (PIN) diodes in each sensing antenna and the four PIN diodes in each communication antenna. These include a scanning UWB mode, fourteen modes to notch WiMax/Cband/<a name="_Hlk120169348"></a>wireless local area network (WLAN)/Xband/ITU in single/dual/triple/quad band rejection states and three interweave modes where each targeting one of the regions of WiMax/Cband/WLAN. Simulated by CST v.10; results like input reflection coefficient and realized gain verify system's capability to work in each operation mode. Moreover, mutual coupling, envelope correlation coefficient and diversity gain all evidence the performance of the proposed system as a MIMO system. Results, simple and compact profile, wide and flexile range of MIMO operation modes in line with the novelty to handle both underlay and interweave cognitive radio all nominate this system as promising to fulfill the needs of modern wireless communications.</span>

A Frequency Reconfigurable Compact Planar Inverted-F Antenna for Portable Devices

In this paper, a low-profile, compact size, inexpensive, and easily integrable frequency reconfigurable antenna system is proposed. The proposed antenna consists of an inverted-F shape antenna, capacitors, and switching PIN diodes. The designed antenna element is fabricated on easy available and less expensive FR-4 substrate ( ε r = 4.4, tan δ = 0.02). The switching diodes are incorporated within the radiating structure of the antenna design, and by changing the different states of PIN diodes, frequency reconfigurable response is achieved. While adjusting the different states of the diodes, the antenna resonates between 0.841 GHz and 2.12 GHz and covers six different frequency bands. The proposed system has compact size of 44 × 14 × 3.2 mm 3 . The gain of the antenna is between 1.89 and 2.12 dBi. The measurement results shows the good agreement with simulated results for different key performance parameters. Additionally, the proposed antenna shows omni-directional far-field characteristics for various different frequencies.

Wirelessly Automated Reconfigurable Antenna With Directional Selectivity

In this paper, a frequency reconfigurable antenna system with a directional selectivity is presented. The reconfiguration of the antenna’s radiation characteristics is wirelessly controlled through a mobile phone and a microcontroller. The antenna system is a multi-element radiator composed of four monopoles on top of a hexagonal ground plane, in addition to four rectangular microstrip two-elements antenna arrays. The monopoles and the microstrip arrays are designed to contribute to the communication requirements of the complete system. The position, orientation, and topology of the various antennas are optimized to achieve the required frequency reconfigurability in addition to the variable selective directivity performance. The whole system is fabricated and integrated in a single compact unit controlled by a microcontroller, four servo motors, and a Bluetooth module. The antenna system is tested and the measured results confirm the validity of the proposed design.

주파수 재구성 가능한 방사 구조를 갖는 영차 공진 안테나

본 논문에서는 주파수 재구성 기능이 가능한 방사 구조 갖는 co-planar waveguide (CPW) 급전 방식의 영차 공진 안테나를 제작하고 측정하였다. 제안된 안테나의 단위 셀은 직렬 metal-insulator-metal (MIM) 형태의 커패시터와 두개의 단락된 병렬 스터브 인덕터로 구성되어 있다. 제안된 안테나는 두 개의 단위 셀을 갖는 composite right/left-handed (CRLH) 전송 선로에 근거하여 설계되었으며 선로의 끝단을 개방하여 선로의 병렬부에서 주된 전자파 에너지 방사가 이루어지도록 하였다. 안테나의 크기를 소형화시키는 동시에 다이오드 스위치 부착을 통하여 주파수 재구성 안테나를 구현하기 위하여 비아를 통하여 접지 면과 연결 되어지는 4개의 90<SUP>0</SUP> 접혀진 단락 스터브 선로를 병렬 인덕터 구조로 사용하였다. 제안된 안테나의 영차 공진 주파수는 3.09 GHz이고 전체 크기는 0.22λ<SUB>0</SUB> ×0.16 λ<SUB>0</SUB> 이다. 제작된 안테나의 측정 결과 영차 공진 주파수 2.97 GHz에서 안테나의 최대 이득과 임피던스 대역폭은 각각 3.1 dBi와 56MHz를 나타내었으며, 삼중 대역에서 동작하는 주파수 재구성 안테나 시스템에 응용이 가능하다.

Implementation of a Cognitive Radio Front-End Using Rotatable Controlled Reconfigurable Antennas

This communication presents a new antenna system designed for cognitive radio applications. The antenna structure consists of a UWB antenna and a frequency reconfigurable antenna system. The UWB antenna scans the channel to discover “white space” frequency bands while tuning the reconfigurable section to communicate within these bands. The frequency agility is achieved via a rotational motion of the antenna patch. The rotation is controlled by a stepper motor mounted on the back of the antenna structure. The motor's rotational motion is controlled by LABVIEW on a computer connected to the motor through its parallel port. The computer's parallel port is connected to a NPN Darlington array that is used to drive the stepper motor. The antenna has been simulated with the driving motor being taken into consideration. A good agreement is found between the simulated and the measured antenna radiation properties.