Ang Yu

A DUAL BAND CIRCULARLY POLARIZED RING ANTENNA BASED ON COMPOSITE RIGHT AND LEFT HANDED METAMATERIALS

In this paper a dual band circularly polarized antenna is designed, fabricated, and measured. Based on the concept of composite right and left handed (CRLH) metamaterials, the same phase constants and current distributions on the ring antenna are achieved at two frequency bands. Thus, the antenna has similar radiation patterns at both bands. The circular polarization is implemented by feeding two vertical ports from power dividers that provide equal magnitudes and quadrature phase excitations.

An Offset-Fed X-Band Reflectarray Antenna Using a Modified Element Rotation Technique

An X-band circularly polarized reflectarray antenna with an offset feed is designed, fabricated, and measured. The proposed design features the use of split square ring elements with a modified element rotation technique for phase compensation, which allows the rotation of the slot instead of the element itself. This is crucial in single-layer multiband reflectarray antenna designs where it is desired to minimize the effectively occupied area by individual elements. A design flow chart of the reflectarray antenna is summarized, and the element/system design procedure is presented in details. A reflectarray prototype was measured in a near field measurement system, which operates at 8.4 GHz with a gain of 30.4 dB and an aperture efficiency of 53.7%. Both the axial ratio bandwidth (AR <; 3 dB) and the 3 dB gain bandwidth are 6%.

Experimental demonstration of a single layer tri-band circularly polarized reflectarray

The reflectarray antenna is a substitution of reflector antennas by making use of planar phased array techniques [1]. The array elements are specially designed, providing proper phase compensations to the spatial feed through various techniques [2–4]. The bandwidth limitation due to microstrip structures has led to various multi-band designs [5–6]. In these designs, the multi-band performance is realized through multi-layer structures, causing additional volume requirement and fabrication cost. An alternative approach is provided in [7–8], where single-layer structures are adopted. The former [7] implements a dual-band linearly polarized reflectarray whereas the latter [8] establishes a single-layer tri-band concept with circular polarization (CP). In this paper, a prototype based on the conceptual structure in [8] is designed, fabricated, and measured. The prototype is composed of three sub-arrays on a single layer. They have pencil beam patterns at 32 GHz (Ka-band), 8.4 GHz (X-band), and 7.1 GHz (C-band), respectively. Considering the limited area, two phase compensation techniques are adopted by these sub-arrays. The varied element size (VES) technique is applied to the C-band, whereas the element rotation (ER) technique is used in both X-band and Ka-band.

A Single Layer Reflectarray Antenna for C/X/Ka Bands Applications

This paper proposes a novel tri-band reflectarray antenna design. The antenna consists of three different types of elements: split circular ring for Ka band operation, split square loop for C band operation, and cross-dipole element for X band operation. An advantage of the antenna is that all three types of elements are aligned and fabricated on a single layer of substrate. This single-layer design will be significantly simpler to fabricate with lower cost than the traditional multilayer designs.

An X-band circularly polarized reflectarray using split square ring elements and the modified element rotation technique

Using split square ring elements and the modified element rotation technique, an X-band circularly polarized reflectarray is designed and implemented through microstrip technology. At 8.4 GHz, the reflectarray prototype has a gain of 30.4 dB and an aperture efficiency of 53.7%. The fractional axial ratio bandwidth is 6%, while the 3 dB gain bandwidth is 7%.

A single layer broadband circularly polarized reflectarray based on the element rotation technique

This paper investigates the performance of the single slot ring element for Ka-band reflectarray designs. Using the element rotation technique, two Ka-band circularly polarized reflectarray prototypes are designed and implemented, with different thicknesses of the substrate. The bandwidth is significantly enhanced when a thick substrate is used.

Analysis of bow tie array RFID tag antenna for paper reel identification systems

This paper presents an analysis and measurement results of using bow tie array-type tag antenna design in paper reel identification. The advantage of the bow tie array compared to a single bow tie is better readability from the opposite direction to S. This indicates that the bow tie array can harvest energy to the microchip and backscatter the identification data to the reader more efficiently from the backside of the reel. Future work includes read range testing using industrial paper reels to confirm the omnidirectional performance. To improve the radiation patterns and to further increase the read ranges, optimization of the array feed lines and the impedance matching to the microchip will be carried out.