3D printing technique for the development of non-planar electromagnetic bandgap structures for antenna applications

The use of 3D printing for the development of non-planar electromagnetic bandgap (EBG) structures for antenna applications is proposed. A coplanar waveguide (CPW) fed antenna is tested on a non-planar EBG substrate, fabricated using additive manufacturing techniques. Inexpensive fuse filament fabrication is used as the fabrication process. Silver-loaded conducting ink is employed for the metallic components of the EBG. The CPW antenna on the non-planar EBG structure has a satisfactory reflection coefficient at 2.45 GHz, which is suitable for Bluetooth/WLAN communications. The radiation patterns have reduced back lobes and improved gain compared with the antenna in free space

Electromagnetic Coupling through Arbitrary Apertures in Parallel Conducting Planes

We propose a numerical methodto solve the problem of coupling through finite, but otherwise arbitrary apertures in perfectly conducting and vanishingly thin parallel planes. The problem is given a generic formulation using the Method of Moments and the Green's function in the region between the two planes is evaluated using Ewald's method. Numerical applications using Glisson's basis functions to solve the problem are demonstrated and compared with previously published results and the output of FDTD software

An application of active frequency selective surface to reconfigurable antenna technology

This paper illustrates the use of active frequency selective surfaces (FSS) in reconfigurable antennas. A patch-form dual-polarized tunable FSS is adapted for use as an active artifi-cial magnetic conductor (AMC). As with the tunable FSS, the ac-tive AMC offers independent tuning capability of the reflection phases for two polarisations of incident EM waves. By combining the AMC with a wideband coplanar waveguide fed monopole an-tenna, circularly polarisation (CP) capability is realized at any fre-quency over the 1.15-1.60GHz band. Furthermore, the CP state can be switched between left hand CP and right hand CP, by simply interchanging the capacitances of varactors controlling the reflection phases of the two orthogonal polarised waves. The an-tenna covers the frequency bands of all operational and in-prepa-ration satellite navigation systems, including GPS, GLONASS, Beidou and Galileo. polarization reconfigurable circular polar-ized (CP) antenna using active artificial ground (AG) structur

Wideband Metamaterial Crossed-Arm Unit Cell for the Design of Beam-Scanning Circularly Polarized Reflectarray Antenna

This paper presents a reconfigurable metamaterial unit cell using crossed arms and its application in designing a wideband beam-scanning circularly polarized (CP) reflectarray (RA) antenna. The unit cell is comprised of two pairs of reconfigurable rotated crossed-arms. One pair is connected by two line strips, and the other pair is connected by two arc-shaped strips. The unit cell is verified with a broad CP reflection bandwidth of 7.7-15.5 GHz. An equivalent circuit is utilized to illustrate its working principle for wide CP reflection bandwidth. Based on this meta material unit cell, a broadband RA antenna was designed, developed, and tested for the initial CP performance verification. A high gain of 26.3 dBic with the maximum aperture efficiency of 58.3 % is obtained for this fabricated RA antenna. In addition, a broad CP bandwidth (from 7.6 GHz to 15.9 GHz) for axial ratio <3 dB is achieved for the high gain unidirectional CP radiation

A Novel Reconfigurable EBG Structure and Its Potential Use as Liquid Sensor

A novel reconfigurable antenna using a modified electromagnetic band gap (EBG) structure is introduced. The EBG is made of an array of square patches with a series of cuts and grooves in the dielectric material between the patches. These grooves allow for the deposition of liquids that can be used to change the resonant frequency of the antenna. The variation in the dielectric permittivity of the liquids produces a change in the reflected phase of the EBG. This change in phase is detected using a planar antenna placed at a short distance from the EBG structure. The change in phase in the EBG produces a change in the reflection coefficient of the antenna. This relationship is shown to be linear for lossless liquids. The reconfigurable structure could also be used as a sensor or detector. In order to assess the use as a sensor, Butan-1-ol, propan-2-ol, ethanol and methanol have been tested. The reflection coefficients and the radiation patterns were measured. Simulations were carried out simulated and measured results

Low Power CMOS Chopper Preamplifier Based on Source-Degeneration Transconductors

This paper describes the design of a low-power, low-noise flicker CMOS chopper preamplifier for sensor signal conditioning. The core amplifier and the Gm-C output low pass filter of the proposed fully differential preamplifier are based on a source degeneration transconductor. The circuit was designed in a standard 0.18µm CMOS process with 1.8V supply voltage. It shows 42dB gain, 1 kHz bandwidth and a total power consumption of 84 µW. The proposed configuration achieves a noise efficiency factor of 4.6 and a total input-referred noise of 560 nVrms integrated from 0.1 to 1 kHz

Integrated filtering-antenna with controllable frequency bandwidth

An integrated design of a band-pass filter and a patch antenna is proposed in this paper by using an aperture coupled structure. Traditionally, the microwave filter and antenna are designed separately using 50 Ohm interface and then connected by transmission lines, which lead to a large size and more loss. Here, the antenna and microwave filter are directly integrated without a 50 Ohm interface between them. Compared with the traditional cascade designing, the co-design of filter and antenna has a more compact size, simpler configuration, improved frequency selectivity and higher system efficiency. The frequency bandwidth also can be controlled by adjusting the dimension of the coupling aperture in the ground. The measured results agree very well with the simulations, showing the filtering-antenna has good performance in impedance matching, radiation pattern and antenna gain

Circular polarised antenna fabricated with low-cost 3D and inkjet printing equipment

The fabrication of a patch antenna using low-cost 3D printing equipment is presented. A circular polarised (CP) patch antenna is manufactured by combining inkjet printing and stereolithography (SLA) technology. The substrate has been fabricated by curing photosensitive resin while the patch element of the antenna has been inkjet printed using silver ink. The printed antenna satisfies the required reflection coefficient, axial ratio and radiation pattern at 1575 MHz. The aim is to demonstrate an inexpensive technology that could be used for the fabrication of antennas on customised 3D printed substrates. The performance of the antenna is summarised through simulations and experimental results

Frequency Tunable and Circular Polarization Switchable Antenna using Dual Polarized Active Artificial Ground Structure

This paper presents a frequency and polarization reconfigurable circular polarized (CP) antenna using active arti-ficial ground (AG) structure. The active AG structure offers independent and symmetrical tuning capability of the reflection phases for dual polarized incident waves. By combining the AG structure with a wideband coplanar waveguide fed monopole antenna, and tuning the capacitances of the varactor diodes on the AG structure, CP wave is dynamically realized at any desired frequency over a wide band in the 1.15-1.60GHz range. At each frequency, the CP state is switchable between left hand CP and right hand CP, by simply swapping the capacitances of varactors controlling the reflection phases of the two orthogonal polarized waves. The antenna covers the frequencies of all operational and in-preparation satellite navigation systems, including GPS, GLONASS, Beidou and Galileo