In this article, ultra-wideband (UWB) monopole antenna with circular polarization (CP) is designed and implemented. The proposed antenna consists of an asymmetric shaped radiator fed by a microstrip line and a limited ground plane on the back side of the substrate. The overall size of proposed antenna is 28 mm × 29 mm, which is suitable for mobile devices. The antenna is fabricated on inexpensive FR4 a dielectric constant of, loss tangent tan = 0.019 with thickness of 1.6-mm. The measured results show that the proposed monopole antenna has a very wide bandwidth from 2.98 to 10.93 GHz that covers the UWB application range and defined by 10-dB return loss. Furthermore, a very wide CP bandwidth of 3-dB axial ratio bandwidth that ranges from 7.18 to 10.01 GHz is achieved. © 2012 Wiley Periodicals, Inc

In this letter, to the best of authors' knowledge, the first MMIC DPA realization in the X-band frequency range has been presented. A clever solution, that allows to reduce the size and to enlarge the bandwidth of the DPA, was adopted to realize the required uneven power splitter.Experimental results have shown a bandwidth larger than 20% around 9.5 GHz with a small signal gain of about 7 dB. Moreover, a 30-dBm saturated output power and a drain efficiency greater than 53% at 9.5 GHz have been measured. In the 6-dB power back-off (from 18 to 24 dBm input power), an AM/ AM distortion lower than 1 dB is also demonstrated with an average efficiency greater than 50%. ACKNOWLEDGMENTThe authors acknowledge SELEX-SI for its technology and modeling support. REFERENCES 1. W.H. Doherty, A new high efficiency power amplifier for modulated waves, ABSTRACT: Antenna communication technologies were developing fast in recent research area, and these technologies demand high performance antenna to coop with the development. Wireless local area network (WLAN) application is famous term in antenna field nowadays, where this application allowed the users to communicate in long range without wired connection. WLAN demands an antenna with small size and volume, low in cost and weight, easy to design, and can perform efficiently at two distinct frequencies. In this article, the dual-band antenna working at 2.45 and 5.8 GHz was proposed. The proposed antenna consists of L-slots and arm's slot, where these slots greatly influenced the dual-band ability. The combination of 45 of bending angle at all antenna edges and slots can enable the proposed antenna to have good performances in term of return losses, bandwidth percentages, and larger half-power bandwidth (HPBW) values at both frequencies. The proposed antenna works efficiently at 2.45-and 5.8-GHz frequency bands when this antenna gives return loss values of À25.1718 and À28.6754 dB, correspondingly. This device can generate a broad forward beam that covered À62.1 to 62.1 HPBW with 36% bandwidth at 2.45 GHz, whereas at 5.8-GHz band, the HPBW for this antenna covered from À77.4 to 52.2 with 7.04% bandwidth. The proposed antenna suits to be used in WLAN's applications such as in Wi-Fi, Bluetooth, and access point application. The proposed antenna measurement values meet the IEEE 802.11 standard to make this antenna reliable.ABSTRACT: A miniaturized bandpass filter (BPF) using dual-mode defected ground waveguide (DGW) resonator is developed in this letter. The technique with defected step-impedance shunt stub is applied to enhance the self-inductance and self-capacitance of the DGW loop resonator which leads to size reduction. Compared to the conventional design, the central frequency is reduced by 48%. A good agreement between simulation and measurement verifies the validity of this design methodology.