Abstract-In this letter, a log-periodic dipole array (LPDA) antenna operating between 1.1 and 13.8 GHz with and an average peak realized gain of 5.2 dB is presented. It is suitable for GPS (L1-L5), PCS, IMT-2000, Bluetooth, WLAN, WiMAX, UWB, and X-band applications. The antenna is designed by introducing a subsectional tapered feedline instead of standard microstrip feeding, which leads to a remarkable lower-frequency performance. The upper-frequency performance of the antenna is improved by adding a feeding point patch. The group delay is also examined for the final design, and maximum 1.5 ns deviation is observed in UWB. By using ordinary and simple dipoles with this modified feedline approach, a superior antenna performance is obtained over a very wide frequency band, and it is validated by the comparison of three fabricated antennas. Additionally, the antenna size is also reduced without using complicated and/or top-loaded dipole structures.Index Terms-Feeding point patch, printed log-periodic dipole array antenna, subsectional tapered feeding.

In this letter, multi-band coplanar waveguide (CPW) fed multiple-input-multiple-output (MIMO) antenna is presented for Bluetooth, WLAN and WiMAX applications. The elements of MIMO antenna are identical CPW-fed printed monopole antennas whose bandwidth performances are improved by employing inverse U and meander line slots. In the design of the antennas, a low-cost FR4 substrate is used and the size of the element antennas are optimized as 35 mm x 30 mm. According to the measurements, S 11 is below 210 dB in 2.38 GHz -2.52 GHz and 3.19 GHz -6.44 GHz bands with 0.2 dB and 2.9 dB average peak realized gains, respectively. The element antennas are placed orthogonally and fed independently to obtain MIMO structure whose size is optimized as 42 mm x 62 mm. The performance of MIMO antenna is also examined in terms of diversity parameters such as envelope correlation coefficient and apparent diversity gain, which are lower than 0.02 and higher than 9.9 in the operating bands, respectively.

In this article, two printed planar monopole antennas (PPMA) are presented. In the design of the first PPMA, the structure is divided into sections and they are optimized in the sense of bottom to up strategy. Tapered transitions and inset feed are employed to increase the bandwidth. The antenna operates between 2.37 GHz and 12 GHz with VSWR<2 and an average peak realized gain of 4.95 dB. Therefore, it is suitable for WLAN, WiMAX, UWB, and X-Band applications. The second PPMA is designed by implementing slots on the previous one to include GPS. The resulting antenna operates in the 1.38-1.60 GHz and 2.33-13.74 GHz bands with VSWR<2. As a result, it also includes GPS in addition to the previous bands. The peak realized gain in GPS is 0.47 dB at 1.575 GHz and the average peak realized gain is 4.41 dB for the 2.33-13.74 GHz band. The group delay performances of the proposed PPMAs are also examined and the maximum group delay deviations of the first and the second PPMAs are observed as 1 ns and 1.33 ns, respectively. V C 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:257-261, 2016; View this article online at wileyonlinelibrary.com.

Abstract-In this paper, a printed planar monopole antenna (PPMA) is presented for PCS, UWB and X-band. The antenna is designed in two stages. In the design of the preliminary PPMA used to obtain the proposed PPMA, the structure is divided into sections, and they are optimized in the sense of bottom to up strategy. The bandwidth is enhanced by employing tapered transitions and inset feed. The resulting antenna operates between 2.37 GHz and 12 GHz with VSWR < 2 and an average peak realized gain of 4.95 dB. Therefore, the preliminary antenna can be considered to be suitable for Bluetooth, WLAN, WiMAX, UWB and X-band. The proposed PPMA is designed by implementing slots on the preliminary PPMA to include PCS, and to suppress Bluetooth and commonly used WLAN and WiMAX bands, the ones allocated out of UWB. The proposed antenna operates in the 1.67 GHz-1.91 GHz and 3 GHz-15 GHz bands with VSWR < 2. The peak realized gain (G pr ) in PCS is 1.32 dB at 1.8 GHz, and the average G pr is 5 dB for the 3 GHz-15 GHz band. The group delay performances are also examined, and the maximum group delay deviations of preliminary and proposed PPMAs are observed as 1 ns and 1.25 ns, respectively.

In this article, a wideband printed bow‐tie antenna is designed entire band of GPS (L5), PCS, IMT‐2000, Bluetooth, Wi‐Fi, WiMAX bands, and the most of frequency range of UWB. Apart from the traditional designs, the proposed antenna includes tapered printed line with a feeding point patch and triangular bows with rectangular edge extensions, which makes the antenna more compact. The antenna realized at the frequency band of 1.49‐9.5 GHz (more than 6.3:1 ratio bandwidth) has the dimensions of 122 mm × 56 mm (0.61λ0 × 0.28λ0). According to measurement results, the realized gain varies between almost 1 and 6.5 dBi with 4.44 dBi average, which are in good agreement with simulation results. Radiation patterns at the lower frequencies of operating band show dipole like radiation pattern with higher cross‐pol discrimination levels while they degrade at the higher frequencies due to increase in gain.