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This paper presents a dual-band printed monopole antenna backed with an electromagnetic band-gap (EBG) array for LTE, WLAN, Wi-MAX, and ISM band applications. The antenna is comprised of a T-shaped monopole, 50 Ω microstrip feed line, and a rectangular-shaped partial ground plane. The printed monopole antenna is supported by a 6 × 6 array of EBG unit cells, with each unit cell composed of square and circular rings, resulting in a wide impedance bandwidth and improved gain. The EBG-backed printed monopole antenna with partial ground plane offers an impedance bandwidth of 57.8% (1.6–2.9 GHz) and a maximum radiation efficiency of 95.4% with a peak gain of 6.9 dB in the first band, and an impedance bandwidth of 53.24% (3.39–5.85 GHz) and a maximum radiation efficiency of 95.2% with a peak gain of 8.7 dB in the second band. The proposed monopole antenna design is miniaturised, has less design complexity, and does not require vias for EBG realisation. [ABSTRACT FROM AUTHOR]

The SIW antenna suffers from the narrow bandwidth for a single cavity and single resonant. Defected ground structure (DGS) with a dual cavity was the solution to solve narrow bandwidth by resulting in hybrid resonance. The hybrid resonance with 14.83% impedance bandwidth is proposed in this antenna design. The first resonance resulted from the combination of the TE101 modes from inner and outer HMSIW cavities while the second resonance resulted from the combination of the strong TE101 and the weak TE102 mode from the inner HMSIW cavity and the addition of the weak TE101 from the outer HMSIW cavity. The measurement antenna design has a broadband antenna with a 14.31% (5.71 – 6.59 GHz) impedance bandwidth by using substrate Rogers RO 5880.

Variations of U-slot and pair of rectangular slots (E-shape) cut rectangular and square microstrip antenna are reported for the circularly polarized response. In the reported literature, details about the functioning of the two designs in terms of the resonant modes present, with a comparison amongst them, are not discussed. This paper provides a detailed review-based study to explain the functioning of the resonant slot-cut circular polarized microstrip antenna in terms of the resonant modes present. This study reveals that TM11 mode in an E-shape microstrip antenna and degenerated TM10 modes in a U-slot design yield the circularly polarized response. Amongst the two, U-slot cut design offers stable gain characteristics across the axial ratio bandwidth and offers a dual-band frequency response. A design methodology based on the resonant length formulation is presented that helps in realizing both the circularly polarized configurations as per the given frequency of interest. Thus, the present work provides a detailed review-based study about the functioning of resonant slot-cut microstrip antenna and its design methodology, which is not discussed in the reported literature. [ABSTRACT FROM AUTHOR]

Antennas are an important component in wireless communication systems that continue to grow in the use of the 2.4 GHz frequency for 4G/LTE applications. Technology in the field of telecommunications has developed very rapidly using wireless communication, which is easily accessible by various devices, for example, Wi-Fi or Wireless Fidelity. Microstrip antenna is one type of antenna that has a narrow bandwidth, small gain. This research aims to widen the bandwidth by designing and manufacturing a truncated corner microstrip patch antenna with a 2x4 array at a frequency of 2.4 GHz with a U-slot. The truncated corner method is used to obtain circular polarization. The truncated corner microstrip antenna is designed by cutting corners. The array method is used to obtain the maximum gain value, while the addition of U-slot aims to reduce the return loss and Voltage Standing Wave Ratio (VSWR) values.

This article examines and studies the impacts of a U-shaped slot in the ground plane of a rectangular microstrip patch antenna with a finite ground plane. To build a compact patch antenna, the U-shaped slot's ideal size and placement have been considered. The size of the patch is 10.6 × 7.8 mm² and the size of the overall rectangular antenna structure is only 31.8 × 23.4 mm² including modified ground backside plane. The reference antenna's resonant frequency is 10 GHz and after the incorporation of U-shaped slot at the ground plane that resonant frequency lowered to 2.1 GHz. By the parametric studies almost 96 % compactness has been found possessing the slot’s optimum dimension. The improved antenna’s gain has been identified as 2.5 dBi. In this literature a study on compactness of rectangular microstrip antenna has been discussed and the effects of U-shaped slot on the finite ground plane over the resonant frequency, return loss and bandwidth have been analyzed. By adjusting various slot parameters in parametric research and selecting the best value of slot’s dimension and position, it has been determined that the modified antenna's resonance frequency is 2.1 GHz. [ABSTRACT FROM AUTHOR]

In this study, a compact U-slot patch antenna design based on dielectric measurement approach of Flame Retardant 4 (FR4) material is presented for X band space applications. In accordance with the design method, the measured frequency dependent dielectric constant and tangent loss values of the FR4 material at X-band using the waveguide method is applied to the HFSS design tool to be used in antenna designs. Then, the functional performance of the design method on antennas is verified by comparing the simulation and measurement results of a conventional antenna design in the literature. In the light of the verified results, a new U-slot patch antenna design with lateral side slots for X-band space applications is presented with a feed line by using the proposed design method. The presented compact antenna design provides 1.77 dB gain at the center frequency (9.5 GHz) and the frequency bandwidth from 8.53 GHz to 10.63 GHz. [ABSTRACT FROM AUTHOR]

Wideband and circular polarized designs of rectangular microstrip antennas employing offset positions of the U-slot and rectangular slot are presented. Query ID="Q1" Text="'EXTC' expand" An inter-spacing between the patch TM10, TM11 and TM02 resonant modes is optimized due to the presence of two offset slots that yields a wideband response with the presence of circular polarized bandwidth towards the higher frequencies, thus providing separate regions for the two responses. In 900 MHz spectrum, the proposed design yields maximum impedance bandwidth of 298 MHz (32.07%) with an axial ratio bandwidth of 13 MHz (1.26%). The proposed designs exhibit pattern maximum in the broadside direction with a gain of larger than 6 dBi. Simulated results have been verified using the experimentation, which shows close agreement. [ABSTRACT FROM AUTHOR]

A penta-mode concept is proposed for the design of single-fed ultrawideband circularly polarized (CP) antennas. The concept involves five linearly polarized (LP) modes in a way that each two adjacent LP modes are designed with orthogonal polarizations of equal amplitude and quadrature phase difference. In this manner, each LP mode is shared by two LP modes nearby except for the first and the last mode in the band. As a result, the CP bandwidth is significantly improved. For proof of concept, a stacked U-slot patch antenna is proposed and designed with a characteristic mode analysis (CMA). The five modes are designed by optimizing the U-slot and the coupling between stacked patches. With the single-fed CP antenna element, a $2\times $ 2 CP array is further designed and prototyped. The measured CP bandwidths of antenna element and array are 52.7% [within 2:1 voltage standing wave ratio (VSWR) and 3 dB axial ratio] and 74% (within 2:1 active VSWR and 3 dB gain), respectively, a significant improvement compared with the conventional CP stacked structures of similar thickness or volume. [ABSTRACT FROM AUTHOR]

One of the major drawbacks of the U-slotted wideband microstrip patch antennas, i.e., the polarization instability at the high-end frequencies, is addressed by utilizing the next broadside TM12 mode in circular patch antennas. The proposed antenna is capable of generating stably polarized waves over a wide frequency range of ~45% (2.05–3.25 GHz), which is not the case with the reported literature on U-slotted wideband patch antennas. The antenna comprises the U-slot and appropriately positioned shorting vias to achieve the desired impedance and radiation characteristics. It is fed by an L-probe and loaded with four non-resonating arc slits to suppress the TM12 mode’s E-plane sidelobes, which are very prominent otherwise. The polarization stability of the antenna is demonstrated through the surface current distributions on the patch, radiation patterns, and the x- and y-polarized gain over the frequency range of interest. [ABSTRACT FROM AUTHOR]

A printed monopole filtenna fed by a co-planar waveguide with U-shaped split slot on patch and circular split ring resonator pairs at the other side of feed is proposed in this letter. The compact filtenna of dimension 0.32λ × 0.215λ (λ denotes wavelength corresponding to 2.68 GHz) is capable of providing large bandwidth from 2.68 to 8.72 GHz with dual frequency notch bands over 3.28–3.84 and 4.95–6.02 GHz, primarily to eliminate the WiMAX and WLAN interferences. The dual notched antenna performances are evaluated by simulation and experimental measurement and compared to those of recently reported ultra-wideband (UWB) notched antennas. The proposed filtenna provides bidirectional E-plane and omni-directional H-plane radiation patterns with gain variation of 2–4.5 dBi and average radiation efficiency of 78% in its pass band. Also the filtenna offers minimal dispersion characteristic as stable group delay response, and linear variation of transfer function (S21) is achieved in its pass bandwidth. [ABSTRACT FROM AUTHOR]

Abstract Wide band designs of E-shape and U-slot cut Rectangular Microstrip antennas are discussed which yields bandwidth of 207 (23%%) and 174 (19%) MHz, respectively. For further bandwidth enhancement, various designs of E-shape and U-slot cut rectangular patch antenna with tapered patch width are proposed. Tapering in patch width alters the input impedance at TM 10 mode in E-shape patch and at TM 10 and TM 02 modes in U-slot cut rectangular patch that yields increase in the bandwidth. Tapered design of E-shape patch gives bandwidth of 225 MHz (~26%) and that of U-slot cut patch yields bandwidth of 202 MHz (~22%). In another tapered width design of E and U-slot cut RMSAs, patch width is reduced at both the ends and these designs yields bandwidth of above 270 MHz (29%) and 212 MHz (22.2%), respectively. The varying width patches exhibit broadside radiation pattern with moderate increment in the values of broadside antenna gain. [ABSTRACT FROM AUTHOR]

Abstract Novel design of Phi-shape microstrip antenna for circular polarized response is presented. The placement of dual stubs in Phi-shape structure optimizes the spacing between degenerated orthogonal TM 11 modes of equivalent circular ring patch that yields circularly polarized response. With reference to patch dual orthogonal TM 11 modes and next higher order TM 21 mode, Phi-shape patch yields VSWR bandwidth of nearly 700 MHz (> 55%) with AR BW of 56 MHz (5.64%). The antenna gives broadside radiation pattern with peak broadside gain of above 8.5 dBi over the VSWR bandwidth. [ABSTRACT FROM AUTHOR]

Broadband microstrip antenna using variations of U-slot has been widely reported. However, in most of the reported work, an in-depth explanation about the mode introduced by U-slot and procedure to design U-slot cut antennas at any given frequency is not explained. In this paper, first an extensive analysis to study the broadband response in symmetrical and a new configuration of asymmetrical U-slot cut rectangular microstrip antennas is presented. The U-slot tunes higher-order orthogonal mode resonance frequency of the patch with respect to fundamental mode to realise wider bandwidth. Further formulation in resonant length at modified patch modes in symmetrical U-slot cut antenna is proposed. Frequencies calculated using these formulations show closer agreement with simulated and measured results. Using proposed formulations, a procedure to design U-slot cut antenna at different frequencies over 800-4000 MHz range which shows broadband response is explained. Thus, the proposed work gives an insight into the functioning of widely used U-slot cut antennas and the formulations will be helpful for designing at any given frequency. [ABSTRACT FROM AUTHOR]

In this study, a 28-GHz U-slot array antenna for a wideband communication system is proposed. The U-slot patch antenna structure consists of a patch, two U-shaped slot, and a ground plane. With the additional U-slot, the proposed antenna has around 10% of bandwidth at -10 dB. To increase gain, the U-slot antenna is arrayed to 2×2. The proposed antenna is designed and fabricated. The 2×2 array antenna volume is 41.3 mm × 46 mm × 0.508 mm. The proposed antenna was measured and compared with the simulation results to prove the reliability of the design. The bandwidth and gain of the measurement results are 3.35 GHz and 13 dBi, respectively and the operating frequency is around 28 GHz. [ABSTRACT FROM AUTHOR]

Half-width microstrip leaky-wave antennas (HW-MLWAs) are generally single band. Here, we present a new method to achieve dual-band operation from an HW-MLWA by periodically loading the antenna with U-shaped slots. These dual-band MLWAs are able to steer the beam in forward directions in one band and in backward directions in the other band. One of the antenna designs was prototyped and tested, and excellent agreement between the predicted and measured results were observed. The measured 10-dB return loss bandwidth of the first and second bands are $19.5 \% $ (5.24–6.37 GHz) and $13.2 \% $ (7.9–9.02 GHz), respectively. The antenna can steer the main beam from $30^\circ $ to $65^\circ $ in the first band and from $-46^\circ $ to $-10^\circ$ in the second band by sweeping the frequency from 5.25 to 6.25 GHz and 7.75 to 9 GHz, respectively. The measured peak gain of the antenna is 12.2 and 14.1 dBi in the first and second bands, respectively. Although the antenna parameters are optimized for dual-band operation, the radiation properties in another higher frequency band (third band) are also explored. In the third band, the antenna beam continuously scans from backward to forward direction as frequency increases. Moreover, this U-slot loaded single-layer half-width LWA is easy to fabricate. [ABSTRACT FROM PUBLISHER]

A dual-band single-layer single-feed dual-band U-slot antenna, with linear polarization and single/dual-beam radiation pattern, is proposed for WLAN [2.40–2.4835 GHz and 5.15–5.35 GHz (indoor)] systems. The impedance bandwidths ($\vert{{\rm S}_{{11}}}\vert < - {10}\,\text{dB}$) of 7.3% and 12.7% are achieved at central frequencies 2.40 and 5.25 GHz, respectively. The lower band radiation pattern is a single broadside beam and the peak gain is 6.3 dBi at 2.40 GHz. The higher band radiation pattern is dual-beam and the peak gains are 7.7 dBi and 7.2 dBi for different beams at 5.25 GHz. The simulated results and the measured ones are in good agreement. [ABSTRACT FROM PUBLISHER]

This article presents a coplanar waveguide fed regular hexagonal antenna for ultra wide bandwidth (UWB). Then this antenna is modified to obtain band rejection for the wireless local area network of 5.15-5.825 GHz (IEEE 802.11a) and wireless microwave access of 3.3-3.7 GHz (IEEE 802.16) by incorporating U-shape slots within the hexagonal patch. Notch bands can easily be controlled by few geometry parameters of the U-slots. Return loss, impedance, gain and radiation characteristics of them are studied and discussed here. From the results, it has been observed that the antenna significantly satisfies the Federal Communication Commission's UWB frequency (3.1-10.6 GHz) range while showing the band rejection performance in the frequency bands of 3.3-3.7 and 5.12-5.9 GHz. The antenna gain varies from 2.6 to 6.4 dB over the whole operating band excluding the notch bands. Surface current distributions and transmission line model are used to analyze the effects of the slots. Measured group delay has very small variation within the operating band except notch bands and hence the proposed antenna may be suitable for UWB applications. [ABSTRACT FROM AUTHOR]

A single-layer single-patch four-band U-slot patch antenna, with linear polarization, is proposed for WiMax and WLAN systems. Using this antenna, impedance bandwidths (\vert S11 \vert < -10 dB) of 2.1%, 3.3%, 7.1% and 5.0% were achieved at central frequencies 3.35 GHz, 3.70 GHz, 5.20 GHz and 5.80 GHz, with gains of 7.6 dBi, 8.6 dBi, 8.5 dBi and 9.0 dBi, respectively. This antenna was made by cutting four asymmetrical U-slots in the patch. This structure has the following advantages: (1) the feed is simple, (2) the antenna has single-layer, (3) the structure of the antenna is simple, (4) the asymmetry of the U-slot arm provides one more degree of freedom in the design, (5) the antenna is inexpensive. The design guideline for the proposed antenna is given and the acceptability of the design is verified by other scenarios. The simulated and measured results are in good agreement [ABSTRACT FROM PUBLISHER]

This communication presents a 60-GHz wideband circularly polarized (CP) U-slot patch antenna array of 4\,\times\,4 elements on low temperature cofired ceramic (LTCC). A CP U-slot patch antenna is used as the array element to enhance the impedance bandwidth and a stripline sequential rotation feeding scheme is applied to achieve wide axial ratio (AR) bandwidth. Meanwhile, a grounded coplanar waveguide (GCPW) to stripline transition is designed for probe station measurement. The fabricated antenna array has a dimension of 14\,\times\,16\,\times\,1.1 mm^3. The simulated and measured impedance bandwidths, AR bandwidths, and radiation patterns are investigated and compared. Measured results show that the proposed antenna array has a wide impedance bandwidth from 50.5 GHz to 67 GHz for \vert S 11 \vert < -10~dB, and a wide AR bandwidth from 54 GHz to 65.5 GHz for AR< 3~dB. In addition, it exhibits a peak gain of 16 dBi and a beam-shaped pattern with 3-dB beam width of 20 ^\circ. Moreover, its AR keeps below 3 dB within the 3-dB beam width. [ABSTRACT FROM PUBLISHER]

U-slot patch antennas with Π-shaped feed slot are studied, and numerical results based on the FDTD method are presented. The effects of varying physical parameters are investigated with a goal of understanding the coupling among different resonators. It is found that the U-slot patch antenna can be designed to attain 50% impedance bandwidth as well as 30–40% gain bandwidth. By altering the sizes of U-slot and feed slot, the wideband characteristic can be changed into a dual-frequency characteristic. [ABSTRACT FROM AUTHOR]

Circularly polarized single-layer U-slot microstrip patch antenna has been proposed. The suggested asymmetrical U-slot can generate the two orthogonal modes for circular polarization without chamfering any corner of the probe-fed square patch microstrip antenna. A parametric study has been carried out to investigate the effects caused by different arm lengths of the U-slot. The thickness of the foam substrate is about 8.5% of the wavelength at the operating frequency. The 3 dB axial ratio bandwidth of the antenna is 4%. Both experimental and theoretical results of the antenna have been presented and discussed. [ABSTRACT FROM AUTHOR]

Multiband applications can be realized as a result of designing a double U-slot rectangular patch antenna. The equivalent circuit of a U-slot patch is presented and the return loss is theoretically derived, utilizing the [A] matrix formulation. CST Microwave Studio software was used to design the microstrip antenna with a transmission line feed and simulate return loss and radiation patterns. The antenna was fabricated in-house using a printed board CNC machine and was measured and compared for return loss using a portable network analyzer. The radiation patterns were measured using a laboratory antenna measurement system. The fabricated antenna was installed on a networked WiFi access point, and tested as far as average received power versus distance range. The antenna is simple, low-cost and easy to fabricate and measurements compared well with simulated results. [ABSTRACT FROM AUTHOR]