Yu Ushijima

5.8-GHz Series/Parallel Connected Rectenna Array Using Expandable Differential Rectenna Units

This communication demonstrates series and/or parallel connection of the differential rectenna units. The differential rectenna unit provides high expandability of rectenna arrays due to its balanced structure. The proposed rectenna array produces higher voltage and/or more current by the series and/or parallel connection of the rectenna units. In the measurement, 30% RF-DC conversion efficiency at the power density of 0.03 W/m2 was achieved in all the case of series and/or parallel four-units connected rectenna array. The maximum conversion efficiency was about 38% in the case of the series-parallel connection. As the proposed rectenna arrays can be easily expanded to large scale integrated rectenna arrays, it will be practically attractive for wireless power transmission.

5.8-GHz Integrated Differential Rectenna Unit Using Both-Sided MIC Technology With Design Flexibility

A 5.8-GHz integrated differential rectifying antenna (rectenna) unit with design flexibility is proposed, and its performance is confirmed experimentally. It positively uses both-sided microwave integrated circuit (MIC) technology, and its antenna feed circuit includes filters which suppress 2nd harmonic. This proposed rectenna unit is a very simple, compact and novel configuration. It operates in a differential mode, and effectively integrates an antenna array with a rectifying circuit. Its configuration provides the pragmatically advantages such as antenna array design flexibility and rectenna unit extensibility. Herein, the behavior of the rectenna unit was successfully confirmed under low radio frequency (RF) power density. Maximum RF-DC conversion efficiency at 5.8 GHz of Industry-Science-Medical (ISM) band was approximately 27% with the load resistance of 390 Ω when the received power density (PD) was 0.031 W/m2.

Wide band switchable circularly polarized microstrip antenna using double-balanced multiplier

In this paper, the reconfigurable antenna which excites orthogonal a circular polarization is proposed and the behavior and the characteristics of the antenna are experimentaly investigated. The proposed antenna has the cross slot at the center of the patch, and four diodes are embedded in a star form across the slot. A circular polarization is excited though in a wide band due to the nonlinearity of the diodes. When the bias voltage Vc superimposed on the RF signal is a slighty positive near 0 V, a LHCP is achieved. On the other hand, when Vc is a slightly negative near 0 V, a RHCP is achieved. Therefore, it is easily possible to switch the phase difference of plusmn90 degrees by a bias voltage Vc for those diodes in a wide band. As a result, switchable circular polarization antennas can be achieved in a wide frequency band. The proposed antennas are practically attractive for the wireless communications as a circularly polarized active antenna.

Dual-polarized microstrip array antenna with orthogonal feed circuit

In this paper, a dual-polarized microstrip array antenna with orthogonal feed circuit is proposed. The proposed microstrip array antenna consists of a single substrate layer. The proposed array antenna has microstrip antenna elements, microstrip lines, air-bridges and cross slot lines. For dual polarization, an orthogonal feed circuit uses the Both-Sided MIC Technology including air-bridges. The Both-Sided MIC Technology is one of the useful MIC technologies for realizing a simple feed circuit. The air-bridges are often used for MMICs because it is possible to reduce the circuit complexity. The characteristics of proposed array antenna are investigated by both the simulation and the experiment. Consequently, it is confirmed that the proposed array antenna with the orthogonal feed circuit has dual polarization performance with very simple structure. The proposed array antenna will be a basic technology to realize high performance and attractive multifunction antennas.

Circular polarization switchable microstrip antenna with SPDT switching circuit

Introduction In this paper, a circular polarization switchable microstripp antenna is proposed. In order to realize the circular polarization switchable microstrip antenna, the proposed antenna is excited by a feeding circuit that consists of a 90° hybrid circuit and a novel SPDT switching circuit. The proposed antenna is shown in Fig. 1. The proposed antenna consists of the CP antenna using 90° hybrid circuit and the SPDT switching circuit. It is well known that the CP antenna using a 90° hybrid circuit radiates the circular polarization in Fig. 1(c). According to selection of exciting part of 90° hybrid circuit, LHCP or RHCP is obtained. For circular polarization switching function, the proposed antenna is used the both of input ports of the 90° hybrid circuit and the novel SPDT switching circuit is proposed in Fig. 1(d). Therefore, the CP antenna can be realized to switch the circular polarization. In addition, for a gain enhancement, an array antenna is constructed using this concept as shown in Fig. 2. The feeding circuit of the antennas uses a “Both-Sided MIC technology”[1]. The excellent design flexibility of the “Both-Sided MIC technology” is very effective for a array arrangement[2, 3, 4]. Therefore, the circular polarization switching antennas are realized with simple structure and operation. In this paper, the characteristics of the integrated feeding circuit are investigated experimentally, and the characteristics of the proposed antennas are simulated by Agilent momentum. Consequently, it is verified that the circular polarization switchable microstrip antenna can be achieved.

Linear polarization switchable patch array antenna

In this paper, the linear polarization switchable patch array antenna is proposed and the characteristics of the proposed antenna are investigated experimentally. The proposed antenna consists of a fed patch element and four parasitic patch elements. The fed element has a cross slot at the center of the patch and four switching diodes are embedded in a star form across the slot. The parasitic elements are around the fed element in order to enhance the gain. When the positive voltage is applied to the proposed patch array antenna, the main polarization angle is tilted to −45deg. When the polarity of the bias voltage applied to the diodes is reversed, the condition of the diodes is changed, and the main polarization angle is tilted to +45deg. Consequently, the proposed patch array antenna can radiate and switch two orthogonal polarizations by the polarity of bias voltage for the diodes. Using the parasitic array technology, the gain of the proposed patch array antenna can be increased than that of single patch antenna. The proposed patch array antenna is practically attractive for the wireless communications systems in the near future.

Circular polarization switchable single layer microstrip array antenna

In this paper, a circular polarization switchable single layer microstrip array antenna is proposed and the performances of the array antenna are confirmed experimentally. The array antenna consists of the orthogonal dual linear polarized microstrip array antenna which has several air-bridges, a 90-deg. hybrid circuit and a SPDT switch circuit loading four PIN diodes on a single layer substrate. It is possible to entirely integrate RF circuits with array antennas due to realization of the novel SPDT switch. By integrating the array antenna with both the SPDT switch circuit and the 90-deg. hybrid circuit, the circular polarizations (RHCP, LHCP) can be easily switched by the diode ON/OFF conditions. The design frequency is 10GHz. In the measurement, the 3 dB axial ratio bandwidth of 3.8% is obtained. Therefore, excellent the circular polarization switching performances of the proposed array antenna has been verified.

Orthogonal Circular Polarization Detection Patch Array Antenna Using Double-Balanced RF Multiplier

In this paper, a technical concept and design of circular polarization detection patch array antenna using a double-balanced RF multiplier is proposed. The microwave integration technology is efiectively employed to realize the proposed array antenna. The double-balanced RF multiplier is integrated with an orthogonal planar array antenna. The array antenna which consists of 12 patch elements and the RF multiplier is realized by embedding four zero bias Schottky barrier diodes on a slot-ring. The Both-sided MIC technology is successfully employed to realize the array antenna. The array antenna is realized in a very simple and compact structure as all the antenna elements, feeding circuit and the RF multiplier are integrated on both sides of a dielectric substrate. The ability of the proposed array antenna to detect the orthogonal circular polarization (LHCP and RHCP) is successfully conflrmed by the experimental investigation.

Differential Mode Rectenna Array

This paper reports “Differential Mode Rectenna Array” for the wireless microwave power transmission. A novel differential mode rectenna unit which has antenna array integrated with a rectifying circuit and feed circuit is proposed. Two differential mode rectenna units are partly overlapped in the rectenna array. The advantages of this differential mode rectenna unit are the excellent design flexibility and size extensibility. If they are connected in series/parallel, higher voltage/more current can be easily obtained. The design frequency is 5.8 GHz in ISM band. In the measurement, the maximum RF-DC conversion efficiency of 47 % is achieved when the load resistance is 220 Ω at the RF power density of 0.021 W/m2.

Beam steering microstrip array antenna with orthogonal excitation

In this paper, a novel beam steering microstrip array antenna is proposed and its characteristics are investigated. The proposed beam steering array antenna consists of four square patches and two orthogonal feed circuits using magic-Ts. The patch elements are excited by two orthogonal modes in time-domain. The phase difference of the elements excitation changes according to the amplitude ratio of input signals. Therefore, the beam steering capability is achieved by changing the amplitude ratio of the input signal. In this paper, the beam steering performance is confirmed by EM simulations and experiments.