Single-arm Rectangular Spiral Antenna Research Articles

Beam steering spiral antenna reconfigured by PIN diodes

The paper proposes a new design for a single-arm, rectangular, spiral antenna (SARSA) with a wide azimuth space coverage. The antenna, operating at around 3.3 GHz, is capable of steering the beam in four separate directions in the azimuth plane. Only three DC signals are required to control the seven PIN diodes attached along the spiral arm. The antenna has a 200-MHz-bandwidth around 3.3 GHz with stable maximum beam directions that are defined by setting of the switches. Considerations required in selecting switch positions when designing such antennas for other frequencies, are presented. The measured return loss, radiation pattern and gain, all have close correlation with the simulation results. A detailed comparison of our design with those already proposed in the literature is given.

Performance enhancement for a broadband spiral antenna using a frequency-selective surface and added backing cavity

This article newly proposes to embed a frequency-selective surface (FSS) in a backing cavity to reduce the back-lobe level and depolarization deficiency of a broadband spiral antenna.For demonstration, a single-arm rectangular spiral antenna backed by an FSS-added cavity was created and studied. The cavity-backed antenna has an enhanced main beam and an extremely low back lobe, in contrast with the original spiral antenna without cavity. In addition, the antenna backed by the FSS-added cavity shows better performance, especially in the depolarization reduction and main-beam enhancement, compared with the spiral antenna backed only by the cavity having no FSS. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:715–718, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26613

An HIS-Based Spiral Antenna for Pattern Reconfigurable Applications

Single arm rectangular spiral antenna with four open circuit switches over a high-impedance surface (HIS) is proposed for pattern reconfigurable applications. The HIS plane without vias is utilized to achieve a low-profile antenna design with a net thickness of 5.08 mm. This is equivalent to ~ lambdao/17 for the intended operating frequency of 3.3 GHz. By using the possible sixteen switching combinations a near 360deg beam steering is achieved, and the switched beams do not have a polarization variation from one pattern to another. The realized pattern reconfigurable antenna has both the tilted (thetasmax ges 25deg) and axial (5deg < thetasmax < 10deg) beams, which have an average directivity of 6.9 dBi.

Reconfigurable Scan-Beam Single-Arm Spiral Antenna Integrated With RF-MEMS Switches

A fully integrated solution providing scan-beam capability with a single antenna is presented in this paper for the first time. The proposed system includes a reconfigurable rectangular spiral antenna with a set of micro electro mechanical system (MEMS) switches, which are monolithically integrated and packaged onto the same substrate. The system is based on a single-arm rectangular spiral antenna, capable of changing its radiation pattern using radio frequency-MEMS (RF-MEMS) switches. The rectangular spiral and RF-MEMS switches are monolithically integrated on a conventional microwave substrate printed circuit board (/spl epsiv//sub r/=3.27 and tan/spl delta/=0.004) and quartz substrate (/spl epsiv//sub r/=3.78 and tan/spl delta/=0.0002). The spiral is made out of multiple lines, which are interconnected by RF-MEMS switches strategically located along the spiral. On activating these switches, the spiral overall arm length is changed and consequently its radiation beam direction is changed. The two proposed antennas radiate right hand circular polarization (RHCP) and left hand circular polarization (LHCP) for printed circuit board and quartz substrate respectively. The gain of the two antennas varies between 3/spl sim/6 dBi. They both satisfy the 3-dB axial ratio criterion at their operating frequency band, i.e., at 10 GHz and 6 GHz for the printed circuit board and the quartz substrate respectively. To the best of our knowledge, this is the first truly reconfigurable printed antenna design using MEMS devices as active elements integrated in the same low loss substrate. The excellent performance of the proposed system emphasizes the importance of being able to integrate MEMS switches into the same low loss substrate for antenna applications. This technology pioneers the design of arbitrarily shaped reconfigurable antennas including the design of reconfigurable antenna arrays.

Beam adaptive single arm rectangular spiral antenna with switches

A rectangular spiral antenna with switches is proposed for beam adaptive applications. The excitation of switches introduces variations in the current distribution on the antenna arm, thus causing the beam to steer. A switch is implemented as an element to short-circuit at a point on the spiral arm to the ground conductor (shorted spiral antenna). A shorted spiral configuration using four switches is analysed. For this configuration, both single- and multipoint switching are implemented. Sixteen possible switching cases are investigated. The radiation patterns are measured in the Satimo antenna test facility and numerically supported using the finite-difference time-domain (FDTD) method. Tilted (24°&lt;θmax&lt;44°) and axial (5°&lt;θmax&lt;12°) beams are obtained using various switching cases, thus realising an adaptive antenna. The gain, which is approximately 6.5 dBi, stays uniform within ±1 dB variation and the VSWR remains within an acceptable limit of 2 for the majority of the switching cases.

Tilted- and axial-beam formation by a single-arm rectangular spiral antenna with compact dielectric substrate and conducting plane

A single-arm rectangular spiral antenna is analyzed using the finite-difference time-domain method. The spiral is printed on a finite-size dielectric substrate backed by a finite-size conducting plane. Both the substrate and conducting planes are square with a side length L of less than 0.6/spl lambda//sub 0/ (/spl lambda//sub 0/: wavelength in free space). The radiation pattern is dependent on the outermost arm peripheral length C. The spiral whose peripheral length is within 2/spl lambda//sub g/<C<3/spl lambda//sub g/ (/spl lambda//sub g/: the guided wavelength of the current) radiates a tilted beam of circular polarization. When the peripheral length is decreased to /spl lambda//sub g/<C<2/spl lambda//sub g/, the spiral radiates an axial beam. The axial beam has a wide half-power beam width of approximately 102/spl deg/ (for L/spl ap/0.369/spl lambda//sub 0/) with a gain of approximately 6.7 dB. The axial beam shows a 15% frequency bandwidth for a 3 dB axial ratio criterion. Over this bandwidth, the voltage standing-wave ratio (VSWR) is less than two, as desired. The experimental results for the radiation pattern, gain, axial ratio, and VSWR are also presented.