A compact triple-band coplanar waveguide (CPW)-fed antenna for WLAN/WiMAX applications is proposed. The radiation patch is fed by capacitive coupling of the top transmission line. By only using one metallic strip etched on the bottom of the substrate, tri-band resonances of the antenna are generated. The proposed antenna has a compact size of 30 × 27 mm 2 , which can provide stable omnidirectional radiation patterns in three bands. The measured − 10 dB impedance bandwidths are 150 MHz (2.39-2.54 GHz), 360 MHz (3.37-3.73 GHz) and 1170 MHz (5.02-6.19 GHz), which is suitable for WLAN/WiMAX applications.Introduction: The prodigious rate of development of wireless communication technology as a viable and cost-effective high-speed data connectivity solution demands high-performance multi-band antennas with good radiation characteristics. In view of the practical needs, many promising antennas have been proposed to cover the WLAN (2.4-2.484, 5.1-5.35 and 5.725-5.85 GHz) operation and WiMAX (3.4-3.69 and 5.25-5.85 GHz) standards. These include monopole antennas with several branches to generate low band and two upper bands [1, 2], a slot monopole antenna for dual-band [3], a monopole antenna with a split-ring [4] and a slot-monopole antenna with embedded rectangular parasitic elements [5]. However, these antennas either need large size or the shapes are too complex. In [6], dual-band was achieved by adding L-and E-elements together with a total area of only 8 × 11.3 mm 2 . However, it just covers the WLAN bands.In this Letter, a compact coplanar waveguide (CPW)-fed antenna for WLAN/WiMAX application is proposed. The patch on the bottom of the substrate could generate three resonant modes with an inverted L-shaped strip to further improve the impedance matching performance at 5.5 GHz. The measured impedance bandwidths can cover the 2.4/5.2/ 5.8 GHz WLAN bands and 3.5/5.5 GHz WiMAX bands. In addition, the proposed antenna has the advantages of small size, low profile, a simple structure and cheap production. Details of the antenna design and simulated and measured results are presented and discussed.

Abstract-In this paper, we present a wideband monopole antenna loaded with Composite right/left-handed (CRLH) unit cell for mobile applications. By loading one CRLH unit cell, the monopole antenna can achieve wideband and generate an additional resonant mode much lower than the unloaded antenna's normal frequency. The antenna has a compact size of 0.1λ 0 × 0.15λ 0 at the lowest resonance frequency. Measured impedance bandwidth is 2000 MHz (1710∼3810 MHz), which can cover one more frequency band for WiMAX applications than conventional antenna. Furthermore, it introduces a narrow band for LTE700 applications. Stable omni-directional radiation patterns make it suitable for mobile terminals.

Abstract-This paper presents a compact band stop filter (BSF) based on the dual metal plane configuration with multiple rejection zeros (RZs). Quasi-lumped technique with novel patch-via-spiral dual mode resonator is applied to the design of the proposed filter. Multiple rejection zeros are introduced by open-end stubs for high selectivity. Design equations are obtained by using a lossless transmission line model. The calculated results show that the lower and upper rejection zeros can be easily tuned by the coupling capacitor and the openend stubs respectively. By using the Microstrip-Coplanar-Waveguide (CPW) structure, the size of the proposed filter can be reduced to 12.8 mm × 9 mm (i.e., 0.24λ g × 0.17λ g ), where λ g denotes the guided wavelength at center frequency.

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A compact third-order bandpass filter (BPF) with enhanced stopband characteristics is proposed in this paper. The filter consists of two stepped impedance resonators (SIRs) and a new resonator named closed loop SIR. The closed loop SIR which is embedded into the other two resonators for compact size is not the real structure of SIR, but it is similar to the conventional /4 SIR in some characters. Cross coupling is introduced into the proposed filter to generate extra transmission zero (TZ) near the passband for sharp frequency selectivity. By adjusting the strength of the mixed cross coupling, the location of the extra transmission zero can be controlled. A new filter centered at 1.77GHz has been analyzed, simulated and fabricated to verify the validity of the proposed method. The measured results show that there are three finite transmission zeros near the passband, which are located at 1.4GHz with 54.2dB rejection, 1.58GHz with 35.9dB rejection, 3.72GHz with 48.5dB rejection, respectively. And, the spurious frequencies of the upper-stopband are suppressed below 30dB from 2.5 GHz to 8.0 GHz.