Abstract-A compact microstrip-fed ultra-wideband (UWB) planar monopole antenna with dual band rejected characteristic is presented in this paper. By etching two identical square complementary split ring resonators (CSRRs) in the radiation patch, dual band rejections in the WiMAX and WLAN bands are achieved. The proposed antenna, with the size of 30×34 mm 2 , has been constructed and tested. And the measured results show that the antenna can operate over the frequency band between 3 and 11 GHz for VSWR < 2 with dual band notches of 3.4-3.6 GHz and 5.1-5.9 GHz. Besides, in the working bands, the antenna shows good omnidirectional radiation patterns in the H-plane and monopole-like radiation patterns in the E-plane and has good time-domain characteristic as well.

A concurrent multi-band low-noise amplifier (LNA) for both WLAN and WiMAX applications covering 2.4-2.7 GHz, 3.3-3.8 GHz and 5.1-5.9 GHz is mainly investigated. The proposed LNA consists of two cascaded common-source stages and employs steppedimpedance transformers and series and shunt feedback techniques to obtain good return loss, low noise and high linearity simultaneously. Test results show that the LNA features input and output return loss of 12 dB, gain of 21 dB, and noise figure of 2 dB across the three bands of operation, which are the state of the art among the counterparts.

This paper presents the design of a crossed oval-ring microstrip slot antenna to achieve triple-frequency operation for WLAN/WiMAX applications. The proposed antenna is composed of a rectangular microstrip feed line and a ground plane on which three crossed oval-ring slots are etched. The three crossed slot loops finally excite three resonant modes and the resonant frequencies of the proposed antenna are mainly controlled by the dimensions and locations of the slot loops. The antenna prototype is fabricated and the characteristics are experimentally verified. The measured impedance bandwidths for triple operating bands can reach 840/670/940 MHz with return losses larger than 10 dB, which is enough for WLAN/WiMAX communication. In addition, good radiation characteristics with moderate peak gains are obtained and the measured and simulated results show a good agreement.

Abstract-In this paper, a novel double-band integrated antenna for applications in WLAN is presented and studied. Based on the mature dipole theory, radiation elements are printed on the two faces of a low cost FR4 substrate. The two dipoles are designed on the sides of the feedline, which can reduce the impact of each other availably. The distance between the two arms and the width of the arms plays an important role in improving the impedance matching. Furthermore, by folding the arms efficiently, the current distribution of the proposed antenna is extended, and the dimensions of the proposed antenna can be reduced. The size of the designed antenna is just 34 mm × 24 mm × 1 mm (about 0.27λ × 0.19λ × 0.008λ, λ is the wavelength relative to the frequency 2.4 GHz). Moreover, the prototype of the antenna is constructed and tested, which shows a good agreement with simulated result. The measured bandwidths, ranging from 2.35 GHz to 2.61 GHz and from 4.7 GHz to 6.0 GHz respectively, are obtained with return loss less than −9.54 dB (about 2 : 1 VSWR). The proposed antenna covers 2.4/5 GHz WLAN bands, and radiation patterns with good omni-directional radiation in the operating frequency are observed.

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