Design of triple‐band filters by using asymmetric parallel‐coupled lines

Abstract

In [7], the proposed E-shaped microstrip patch antenna works on basis mode with a broadside radiation pattern, which is current on the surface of the patch has been shown in Figure 2. In this article, a novel high-order mode E-shape broadband microstrip patch antenna, in which current distribution is shown in Figure 3, is introduced to work on high-order mode with divided pattern. MEASUREMENT RESULTThe size of the E-shape broadband microstrip antenna is as follows: WS ϭ 7.0 mm, LS ϭ 10.5 mm, WA ϭ 0.5 mm, WL ϭ 15 mm, LL ϭ 20 mm, WI ϭ 0.5 mm, WN ϭ 7.2 mm, and WO ϭ 0.5 mm.The blank rectangles are the microelectro mechanical system switches (MEMS). The height of the substrate is 1.5 mm. The dielectric constant is 2.5. Figure 3 shows the measured return loss of the proposed reconfigurable E-shape broadband microstrip antenna. When all of the MEMS open, the antenna operates at mode 1. The antenna operates at mode 2 with all of the MEMS closed. The measured return loss of the mode 1 E-shape broadband microstrip antenna has a 2:1 VSWR 10.5-15.00 GHz corresponding to 35.3% at the central frequency 12.75 GHz. The mode 2 E-shape broadband microstrip antenna has a 2:1 VSWR 10.8 -14.00 GHz. Two modes share common frequencies from 10.8 to 14.00 GHz corresponding to 28.5% at the central frequency 12.25 GHz. As one would expect, the frequency responses of the two modes are nearly identical. But the simulation and measured results shows that the reconfigurable radiation pattern band is just from 10.8 to 13.2 GHz, which is smaller than the impedance band, because the high-order E-shape microstrip antenna has the lower efficiency at upper frequencies. Figure 4 displays the radiation patterns at 10.8, 12.25, 13.2 GHz in E-plane. The patterns are complementary with each other in each picture. The highest gain is 4.9 dBi at 10.8 GHz.From Figure 4(a), we can see that the 3-dB beam-width is over 140°, and the gain more than 4.0 dBi appears from Ϫ54°to 53°. Similarly, the highest gain is 5.75 dBi at 12.25 GHz. From Figure 4(b), we can see that the 3-dB beam-width is over 128°, and the gain more than 4 dBi appears from Ϫ56 to 3 and 23-56°, from Ϫ3°to 23°the antenna gain is more than 3.2 dBi. The highest gain is 5.2 dBi at 13.20 GHz. From the Figure 4(c), we can see that the 3-dB beam-width is over 100°, and the gain more than 2 dBi appears from Ϫ53 to 22 and 33°-46°, from 22°to 33°the antenna gain is more than 1.7 dBi. So the types of reconfigurable antennas could be used in the places where wide-beam and high gain together is needed such as GPS system, mobile terminal, or wideangle scanning phased array. CONCLUSIONThis article presents a novel E-shape pattern reconfigurable structure for microstrip antenna. The antennas' operate-modes can be changed with MEMS switches. The antenna pattern can be transformed between two situations. The two patterns compensating each other cover more wide rage. It is important to make widebeam radiation patterns and high gain of microstrip antennas, which can be used in GPS, mobile terminal, or wide-angle...

Microwave metamaterials—from passive to digital and programmable controls of electromagnetic waves

“…Over the past ten years, we have also concentrated on real applications of metamaterials. Besides the arbitrarily dual-band microwave components [20], ultra-wide bandpass filters [21], and other compact microwave devices and antennas [50][51][52][53][54] using LC-circuit metamaterials in the early stage, we took full advantage of gradient-refractive-index (GRIN) metamaterials to invent high-performance lens antennas [55][56][57][58][59][60][61]. We demonstrated the design, realization, and measurement of a 3D Luneburg lens with a flattened focal surface using the transformation optics in the microwave frequency [55], as illustrated in figure 2(a).…”