Broadside Gain Research Articles

Modeling and PCB Implementation of Standing Leaky-Wave Antennas Incorporating Edge Reflection for Broadside Radiation Enhancement

This paper presents the analysis and PCB design of a standing leaky wave antenna for optimal broadside radiation. The edge reflection effects are emphasized as they may affect the resultant field distribution, and hence lead to altered radiation patterns and broadside directivity. Analytical expressions of the resultant field distribution and far-field patterns are derived as a function of the edge reflection. The proposed model was validated by a full-wave simulation on a center-fed microstrip leaky wave antenna. Parametric study showed that the broadside radiation of a standing leaky wave antenna can be significantly influenced by the edge reflection coefficients, including magnitude and phase. The proposed model of edge reflection effects was experimentally verified using a compact leaky wave antenna implemented on a thin PCB with lumped capacitors placed at the edges to enhance broadside gain.

A Novel High-Gain Printed Antenna Configuration Based on $\text{T}{\text{M}_{12}}$ Mode of Circular Disc

The fundamental (TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> ) mode of a circular patch antenna is generally used for broadside gain applications. However, other TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1m</sub> modes (m = 2,3⋯) also radiate in the broadside direction with high directivities, but are avoided due to the occurrence of sidelobes in the radiation pattern. Here, a simple high-gain disc antenna configuration, using high dielectric constant substrates, operating in the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> mode, is presented. At first, through an analytical study, it is shown that by selecting an appropriate value of the dielectric constant, both high directivity and low sidelobe level (SLL) can be attained. Next, it is demonstrated that the excitation of adjacent modes can be reduced significantly by a proper selection of feed location. For a practical antenna design, it is also shown that the SLL can be further reduced using a finite ground plane size.

Dual-Band Operation of a Circularly Polarized Four-Arm Curl Antenna with Asymmetric Arm Length

This paper presents dual-band operation of a single-feed composite cavity-backed four-arm curl antenna. Dual-band operation is achieved with the presence of the asymmetrical arm structure. A pair of vacant-quarter printed rings is used in the feed structure to produce a good circular polarization (CP) at both bands. The cavity-backed reflector is employed to improve the CP radiation characteristics in terms of the 3-dB axial ratio beamwidth and broadside gain. The proposed antenna is widely applicable in dual-band communication systems that have a small frequency ratio. Examples of such a system are global positioning systems.

60-GHz LTCC Patch Antenna Array With an Integrated EBG Structure for Gain Enhancement

This letter presents a 60-GHz $2 \times 2$ low temperature co-fired ceramic (LTCC) aperture-coupled patch antenna array with an integrated Sievenpiper electromagnetic band-gap (EBG) structure used to suppress TM-mode surface waves. The merit of this EBG structure is to yield a predicted 4-dB enhancement in broadside directivity and gain, and an 8-dB improvement in sidelobe level. The novelty of this antenna lies in the combination of a relatively new LTCC material system (DuPont Greentape 9K7) along with laser ablation processing for fine line and fine slot definition ( $50-\mu\hbox{m}$ gaps with $+ / - 6 \mu\hbox{m} $ tolerance) allowing the first successful integration of a Sievenpiper EBG structure with a millimeter-wave LTCC patch array. A measured broadside gain/directivity of 11.5/14 dBi at 60 GHz is achieved with an aperture footprint of only $350 \times 410\hbox{mil}^2$ ( $1.78\lambda \times 2.08\lambda$ ) including the EBG structure. This thin (27 mil) LTCC array is well suited for chip-scale package applications.

Ultra-wide band magneto-electric dipole antenna for radio frequency integrated circuits

A novel differentially fed magneto-electric dipole antenna is proposed and analysed, which is simpler and better in performance than previously designed antennas by various counterparts. The antenna has achieved an impedance bandwidth of 133.3% 0.5-2.5 GHz for a differential reflection coefficient less than −10 dB. The maximum broadside gain 7.5 dBi has been achieved. A unidirectional radiation pattern with stable gain has also been observed for the entire range of frequency operation. Symmetric radiation pattern for both E-plane and H-plane has also been confirmed owing to the symmetry of antenna structure and feed excitation. The cross-polarisation level lower than −30 dB has also been observed for better signal purity.

Psi-shaped Ultra-wideband Monopole Antenna with a Modified Feeding Structure

Novel design of Psi-shaped printed monopole antenna consisting of modified feeding structure is proposed. A detailed parametric study for various antenna parameters that forms the Psi shaped patch is presented. The pair of vertical slots in Psi shaped patch optimizes the antenna bandwidth till 4 GHz of frequency range whereas position of horizontal slots that constitutes modified feeding structure optimizes the antenna bandwidth till 6GHz. Further optimization for bandwidth beyond 7 GHz is obtained by suitably selecting the feed line position along patch base edge which optimizes the input impedance at higher order patch resonant mode. The proposed Psi shaped patch antenna yields BW from 1.5 GHz to more than 10GHz. The proposed configuration shows broadside radiation pattern over most of the bandwidth with peak broadside gain of nearly 2 dBi. Due to the realized antenna characteristics Psi shaped antenna can find applications in Bluetooth, Wi-Fi and personal communication systems for frequencies above 1GHz.

Broadband Slot Cut Rectangular Microstrip Antenna

Variation of E-shaped Microstrip antenna, a broadband rectangular Microstrip antenna cut with three unequal length rectangular slots is proposed. A detail analysis to study the effects of rectangular slots that realizes broader bandwidth is presented. The slot reduces resonance frequencies of orthogonal higher order TM02, TM11 modes and along with fundamental TM10 mode, yields more than 450MHz (>45%) of bandwidth. The realized bandwidth in the proposed configuration is more than the bandwidth obtained in equivalent rectangular patch antenna with U-slot or pair of rectangular slot i.e. E-shaped patch antenna. The proposed configuration gives broadside radiation pattern over the bandwidth with a peak broadside gain of more than 8 dBi.

Wideband Millimeter-Wave Elliptical Cavity-Backed Antenna for Circularly Polarized Radiation

A wideband millimeter-wave antenna backed by an elliptical cavity for circularly polarized radiation, excited by a dipole inclined to the major axis direction of the cavity, is reported in this letter. Experimental results show that the proposed antenna can achieve a bandwidth of 50-62.8 GHz for both axial ratio ≤ 3 dB and reflection coefficient | S 11 | ≤ - 10 dB, and an average broadside gain of 7.8 dBi. Studies on four critical parameters are performed for practical design. This design yields good directional radiation patterns and low fabrication cost.

Circularly Polarized Transmitarray With Sequential Rotation in Ka-Band

We present here the design and demonstration of a circularly polarized (CP) transmitarray antenna operating in Ka-band and illuminated by a linearly polarized (LP) source. The proposed design is based on a CP unit-cell with simulated insertion loss of 0.2 dB at 30 GHz. In order to improve the axial ratio (AR) bandwidth, the sequential rotation technique is applied to the full array configuration. A model based on a hybrid in-house simulation tool is also proposed to predict accurately the array performance. The realized prototype, formed by 400 unit-cells, has 1 bit of phase resolution. The measured broadside gain is 22.8 dBi at 30 GHz with a 3-dB bandwidth of 20% in right-handed CP (RHCP). The obtained 3-dB AR bandwidth of 24.4% is comparable with higher resolution designs.

Investigations on Photoresist-Based Artificial Dielectrics With Tall-Embedded Metal Grids and Their Resonator Antenna Application

Novel photoresist-based artificial bulk dielectrics with tall-embedded metal grids are investigated and their radiation characteristics are studied in detail. The embedded metal grid substantially increases (around six times) the effective permittivity of the low permittivity base photoresist material, and enables excitation with a simple direct microstrip feed to radiate effectively at frequencies similar to a high-permittivity dielectric resonator antenna (DRA). Moreover, the grid changes the near fields inside the resonator and introduces novel modes that are completely different than those of usual DRAs. A set of artificial resonator antennas is designed, lithographically fabricated, and measured to demonstrate the new modes resonating at 17 and 19 GHz with 2% and 6% bandwidth and 7.6 and 6.6 dB broadside gain, respectively, with suitable cross-polarization levels of better than $- {20}\;\text{dB}$ . These new modes do not appear simultaneously, and can be excited separately by varying the length of the microstrip feed.

UWB loop antenna with stable broadside radiation characteristics

ABSTRACTIn this article, a circular loop antenna with stable broadside radiation characteristics for ultrawideband (UWB) applications is proposed. It consists of a circular loop and circular sectors, and the circular sectors are used to directly match a 50‐Ω feed line over a UWB frequency band. The geometry of the proposed antenna is optimized to cover the 3.1–10.6 GHz UWB frequency band with stable broadside radiation patterns. The input impedance and voltage standing wave ratio (VSWR) characteristics of three different structures (a center‐fed circular loop with thin strips, a structure with circular sectors as an end‐truncated semicircular dipole, and the proposed loop antenna with circular sectors) are compared. The optimized proposed antenna is fabricated on a Teflon substrate. It exhibits a measured impedance frequency band of 3.08–12.27 GHz (120%) for a VSWR &lt; 2, which ensures operation in the UWB band. Measured broadside gain is 3.0–7.0 dBi, and stable broadside radiation patterns are observed in the entire UWB band. Measured group delay remains almost constant with a variation of less than ±0.5 ns for the face‐to‐face orientation, and this indicates good time domain performance of the antenna. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2515–2519, 2015

Radiation Characteristics of a Probe-Fed Microstrip Patch Antenna on a Finite Grounded High Permittivity Substrate

Radiation characteristics of a probe-fed rectangular microstrip patch antenna printed on a finite grounded high permittivity substrate are investigated systematically for various square grounded dielectric substrate sizes with several thicknesses and dielectric constants by experiment and full wave simulation. The effect of the substrate size on the radiation characteristics of a rectangular patch antenna is mainly determined by the effective dielectric constant of surface waves on a grounded dielectric substrate. As the effective dielectric constant of surface waves increases, the substrate sizes for the maximum broadside gain and the required onset for a large magnitude of squint angle decrease, while the variations of the broadside gain, the front-to-back ratio, and the magnitude of squint angle versus the substrate size increase due to the increase of the power of the surface wave.

Substrate-Integrated Waveguide-Based 60-GHz Resonant Slotted Waveguide Arrays With Wide Impedance Bandwidth and High Gain

Conventional resonant-slotted waveguide arrays can only achieve a few percent of impedance bandwidth. This paper presents a new substrate-integrated waveguide (SIW)-based 60-GHz resonant-slotted waveguide array, which can achieve both wide impedance bandwidth and high gain. In the design, resonant slots with different resonant frequencies are arranged at unequal spacing along the SIW. The variance of the excitation voltages of different resonant slots is minimized to improve the arrays’ impedance bandwidth and gain. A ${\bf 4} \times {\bf 1}$ -element subarray is designed accordingly, which shows a $- {\bf 10}\mbox{-}{\bf dB}$ impedance bandwidth from 56.5 to 66.7 GHz (16.6%) with a peak broadside gain of 11.5 dBi. Based on this subarray, three other arrays with ${\bf 4} \times {\bf 4}$ , ${\bf 8} \times {\bf 4}$ , and ${\bf 8} \times {\bf 8}$ -slot elements are designed, fabricated, and measured. Long nonresonant slots are placed between each two subarrays to improve isolation. Measured results of the three fabricated arrays show $- {\bf 10}$ -dB impedance bandwidths of 20.8%, 22.4%, 18.8%, respectively, and peak broadside gain of 18.3, 19.9, and 22.8 dBi, respectively. The proposed structures exhibit wider impedance bandwidth and higher peak gain than their former counterparts.

Wideband Magnetoelectric Dipole Antennas With Dual Polarization and Circular Polarization

A new 45 degrees dual-polarized magnetoelectric dipole antenna is proposed. The antenna is excited by two -shaped probes placed at a convenient location. The measured overlapped impedance bandwidth is 48% with standing-wave ratio (SWR) 1.5 from 1.69 to 2.76 GHz. The measured gains vary from 7.6 to 9.3 dBi and from 7.6 to 9.4 dBi for port 1 and port 2, respectively. The isolation between the two ports is larger than 30 dB. The proposed antenna achieves a low cross-polarization level of less than 21 dB and a low back radiation level of less than 29 dB over the operating frequency range. With a broadband 90 phase shifter and a power divider, the proposed antenna can radiate circularly-polarized (CP) wave and exhibit a wide impedance bandwidth (SWR 2) of 90% from 1.23 to 3.23 GHz, which covers the whole 3-dB axial-ratio (AR) bandwidth of 82% from 1.28 to 3.05 GHz. In this operation frequency band, the proposed CP antenna has a broadside gain of larger than 5 dBi above 1.45 GHz. Considering the common overlapped bandwidth limited by the impedance, AR, and gain, the proposed antenna exhibits an effective bandwidth of 71%.

Tapered composite right/left-handed leaky-wave antenna for wideband broadside radiation

A leaky-wave antenna (LWA) based on tapered composite right/left-handed unit cell sections is proposed for wideband broadside radiation. The substrate-integrated-waveguide metamaterial based antenna consists of three sections with varying slot lengths for unit cells. The measured broadside gain of the proposed tapered antenna prototype is higher than 9.0 dBi over a bandwidth of 4.7% (8.825–9.250 GHz). The bandwidth of the proposed tapered LWA for 1-dB gain variation doubles that of the conventional LWA with non-tapered unit cells. In addition, the proposed antenna is able to scan the beam from −72° to +75° over a frequency range of 8.0–13.0 GHz with the gain greater than 9.0 dBi. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:624–629, 2015

DESIGN OF MINIATURIZED QUASI-YAGI ANTENNA FOR PORTABLE RFID READER APPLICATIONS

A method to design a miniaturized two-element quasi-Yagi antenna (QYA) with size and gain requirements is presented for portable ultra high frequency (UHF) radio frequency identification (RFID) reader applications. The antenna consists of a driver dipole and a ground reflector, and these elements are serially connected with a coplanar strip line. The ends of both elements are folded back toward each other to reduce the lateral size of the antenna. A detailed design procedure of the proposed antenna is explained, along with a performance comparison for the input impedance, voltage standing wave ratio (VSWR), broadside gain, front-to-back (F/B) ratio, and total efficiency. A prototype antenna, covering the 860-960 MHz UHF RFID band with a gain > 4 dBi, is fabricated on an FR4 substrate with dimensions limited to 90 mm by 90 mm. The total width of the proposed antenna is reduced by approximately 41% compared to the conventional QYA without miniaturization, and an F/B ratio is improved by 1-8 dB in the band. Experiment results show that the proposed antenna has the desired impedance characteristics with a frequency band of 853-1,098 MHz for a VSWR 13 dB is obtained.

A PHOTOMIXER DRIVEN TERAHERTZ DIPOLE ANTENNA WITH HIGH INPUT RESISTANCE AND GAIN

A terahertz (THz) antenna is proposed that offers high input resistance and gain in the presence of an electrically thick GaAs substrate. The antenna is centrally fed using two vertical probes connected to a photomixer on a thin low temperature grown gallium arsenide (LTG-GaAs) film which is supported by the GaAs substrate. An input impedance of ∼ 3.3 kΩ has been achieved using a dipole antenna that is printed on a thin dielectric slab, and isolated from the supporting substrate using a metal ground plane. A square aperture has been introduced to facilitate the illumination of the photomixer with two laser beams. Furthermore, a frequency selective surface (FSS) has been incorporated in the configuration, which results in a broadside gain of ∼ 19 dBi at a resonance frequency of 0.97 THz.

Design and Performance Evaluation of a Dielectric Flat Lens Antenna for Millimeter-Wave Applications

In this letter, a practical fabrication of a novel inhomogeneous gradient-index dielectric flat lens for millimeter-wave applications is presented. A previous theoretical design of a dielectric flat lens composed of different permittivity materials is now modeled and analyzed for a practical prototype fabrication and performance evaluation at 60 and 77 GHz. The measurement results at 60 GHz show that with the novel gradient-index dielectric flat lens antenna prototype, we can achieve up to 18.3 dB of broadside gain, beam-steering capabilities in both planes from $-30^\circ$ to $+30^\circ$ with around 15 dB of gain, and up to $\pm 45^\circ$ with around 14 dB of gain, with low sidelobe levels. At 77 GHz, the performance evaluation shows that we can obtain up to 18.9 dB of broadside gain, beam-steering capabilities in both planes from $-30^\circ$ to $+30^\circ$ with around 17 dB of gain and low sidelobe levels, and up to $\pm 45^\circ$ with around 15 dB of gain. This novel design leads to a low-cost, low-profile, and lightweight antenna solution, easy to integrate in a compact millimeter-wave wireless communication system.

Novel Multiport Cavity-Backed Antenna for Low-Cost Array Applications

In this letter, a novel three-element linear cavity- backed antenna (CBA) array with high aperture efficiency is proposed. First, in order to reduce the loss and cost caused by the feeding network, a multiport CBA acting as a radiator as well as a power divider is investigated. Then, based on the multiport CBA, a three-element antenna array with a wide operating frequency band (19-21 GHz) is designed. The simulated broadside gain is from 9.7 to 11.1 dBi over the whole operating band, and the aperture efficiency of the proposed CBA array ranges from 99.1% to 123.7%. The proposed idea has potential applications in low-cost antenna arrays due to the simplified feeding network.

Ka-Band Cavity-Backed Detached Crossed Dipoles for Circular Polarization

An implementation of circularly polarized crossed dipoles in millimeter-wave band is presented in this paper. Novel detached crossed dipoles have been designed to tackle the problems confronted by single-fed crossed dipoles in mm-wave band. An evolution procedure from conventional crossed dipoles to the proposed ones is given. Meanwhile, a metallic ridge is added in the cavity to provide a robust feeding structure. Measurements of an optimized antenna prototype show that it can achieve a bandwidth from 27 to 36.8 GHz for both AR ≤ 3 dB and |S11| ≤ -10 dB and an average broadside gain of 12.4 dBi. The measured results agree reasonably well with simulations. For reference to practical designs, studies on five critical parameters have also been performed in this paper.