Resonance conditions for a substrate-superstrate printed antenna geometry which allow for large antenna gain are presented. Asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed. The method is extended to produce narrow patterns about the horizon, and directive patterns at two different angles.

Gain enhancement methods for printed circuit antennas

This paper presents a novel design of a Fabry-Perot (FP) resonator antenna with a wide gain bandwidth in X band. The bandwidth enhancement of the antenna is attributed to the positive reflection phase gradient of an electromagnetic band gap (EBG) structure, which is constructed by the combination of two complementary frequency selective surfaces (FSSs). To explain well the design procedure and approach, the EBG structure is modeled as an equivalent circuit and analyzed using the Smith Chart. Experimental results show that the antenna possesses a relative 3 dB gain bandwidth of 28%, from 8.6 GHz to 11.4 GHz, with a peak gain of 13.8 dBi. Moreover, the gain bandwidth can be well covered by the impedance bandwidth for the reflection coefficient ( ${\rm S} _{11}$ ) below $-10~{\rm dB}$ from 8.6 GHz to 11.2 GHz.

Wideband Fabry-Perot Resonator Antenna With Two Complementary FSS Layers

A novel compact ultrawideband (UWB) printed slot antenna with three extra bands for various wireless applications is presented. The low-profile antenna consists of an octagonal-shaped slot fed by a beveled and stepped rectangular patch for covering the UWB band (3.1-10.6 GHz). By attaching three inverted U-shaped strips at the upper part of the slot in the ground, additional triple linear polarized bands can be realized covering GPS (1520-1590 MHz), part of GSM (1770-1840 MHz), and Bluetooth (2385-2490 MHz). Simulated and measured results are presented and compared, which shows that the antenna has a stable radiation pattern both at the triple and the whole of the UWB bands.

Compact UWB Printed Slot Antenna With Extra Bluetooth, GSM, and GPS Bands

A novel compact tri-band printed antenna for WLAN and WiMAX applications is presented. The proposed antenna consists of a modified rectangular slot, a pair of symmetrical inverted-L strips, and a Y-shaped monopole radiator with a meandering split-ring slot. Tuning the locations and the sizes of these structures, three distinct current paths can be produced at three independent frequency bands, respectively. Based on this concept, a prototype of the tri-band antenna is further fabricated and measured. The experimental and numerical results show that the antenna has impedance bandwidth (for return loss less than 10 dB) of 430 MHz (2.33-2.76 GHz), 730 MHz (3.05-3.88 GHz), and 310 MHz (5.57-5.88 GHz), which can cover both the WLAN 2.4/5.8-GHz bands and the WiMAX 2.5/3.5-GHz bands.

Compact CPW-Fed Tri-Band Printed Antenna With Meandering Split-Ring Slot for WLAN/WiMAX Applications

A single-fed microstrip patch antenna (MPA) with loading of shorting pins for high-gain circularly polarized (CP) radiation is proposed in this paper. Two sets of metallic pins are symmetrically placed along the two orthogonal diagonals of a square patch radiator at first. Due to the shunt inductive effect brought by these shorting pins, the resonant frequency of the dominant mode in this MPA is progressively tuned up so as to enlarge the electrical size of this pin-loaded patch resonator and to enhance its radiation directivity. After the optimal loading position is investigated for maximum directivity of linear polarization, one pair of the inner pins is slightly shifted in an offset to properly separate the two degenerate modes, so that the CP radiation can be excited. Moreover, upon request, either left-handed or right-handed circular polarization can be obtained by means of different position-offset scheme of the inner pins along the diagonals. After extensive analysis is executed, two equal-size CP MPAs with and without shorting pins are fabricated and tested. Simulated and measured results show good agreement and demonstrate that the CP directivity is enhanced from 8.0 (conventional MPA) to 10.8 dBic, indicating a 2.8-dB increment by means of the proposed approach.

High-Gain Circularly Polarized Microstrip Patch Antenna With Loading of Shorting Pins

A simple, low-cost, and compact printed dual-band fork-shaped monopole antenna for Bluetooth and ultrawideband (UWB) applications is proposed. Dual-band operation covering 2.4-2.484 GHz (Bluetooth) and 3.1-10.6 GHz (UWB) frequency bands are obtained by using a fork-shaped radiating patch and a rectangular ground patch. The proposed antenna is fed by a 50-Ω microstrip line and fabricated on a low-cost FR4 substrate having dimensions 42 (Lsub) × 24 (Wsub) × 1.6 (H) mm3. The antenna structure is fabricated and tested. Measured S11 is ≤ -10 dB over 2.3-2.5 and 3.1-12 GHz. The antenna shows acceptable gain flatness with nearly omnidirectional radiation patterns over both Bluetooth and UWB bands.

A Compact Dual-Band Fork-Shaped Monopole Antenna for Bluetooth and UWB Applications

Single-feed, efficient, high-gain antennas using partially reflective surface (PRS) with right-hand/left-hand circular polarization (CP) are investigated. Metallic ground plane and a PRS with square patch (SP) arrays at about 0.5λ0 height form the Fabry-Perot cavity (FPC) that is fed by a circularly polarized microstrip antenna (MSA). Right-handed circular polarization (RHCP) or left-handed circular polarization (LHCP) at the MSA is obtained using a single diagonal feed and shorting posts along x- or y-axes. Constant high-gain performance is obtained by resonating feed patch (FP) and SP arrays in the same frequency band. The effect of the SP array on antenna performance is critically analyzed. Gain enhancement of 10 dB over the circularly polarized MSA is obtained by optimizing PRS structures. Antennas with different PRSs yield peak gain of 9.1-17.3 dBi, and axial ratio (AR) is less than 3 dB over the desired frequency band. Gain variation is less than 1 dB over the frequency band. Measured results validate the design concept and indicate that the proposed structures exhibit good radiation characteristics and are suitable for satellite systems.

Right-Hand/Left-Hand Circularly Polarized High-Gain Antennas Using Partially Reflective Surfaces

In this article, a compact microstrip-fed printed dual band antenna for Bluetooth (2.4{2.484GHz) and UWB (3.1{ 10.6GHz) applications with WLAN (5.15{5.825GHz) band-notched characteristics is proposed. It is demonstrated that dual band characteristics with desired bandwidth can be obtained by using a fork shaped radiating patch, whereas, band-notched characteristics can be obtained by etching two L-shaped slots and two symmetrical step slots on the rectangular ground plane. The proposed antenna is simulated, fabricated and tested. The structure is fabricated on a low cost FR4 substrate having dimensions of 50mm (Lsub) £ 24mm (Wsub) £ 1:6 (H)mm and fed by a 50› microstrip line. The proposed antenna has S11 • i10dB over 2.18{2.59GHz, Bluetooth band, 3.098{5.15GHz and 5.948{11.434GHz, UWB band with WLAN band notch. The structure exhibits nearly omnidirectional radiation patterns, stable gain, and small group delay variation over the desired bands.

/pdf/printed-fork-shaped-dual-band-monopole-antenna-for-bluetooth-2klazi2n4o.pdf

Printed Fork Shaped Dual Band Monopole Antenna for Bluetooth and UWB Applications with 5.5 GHz WLAN Band Notched Characteristics

In this paper, a high gain, low side lobe level Fabry Perot Cavity antenna with feed patch array is proposed. The antenna structure consists of a microstrip antenna array, which is parasitically coupled with an array of square parasitic patches fabricated on a FR4 superstrate. The patches are fabricated at the bottom of superstrate and suspended in air with the help of dielectric rods at 0:5‚0 height. Constant high gain is obtained by resonating parasitic patches at near close frequencies in 5.725{5.875GHz ISM band. The structure with 9£9 square parasitic patches with 1:125‚0 spacing between feed elements is fabricated on 5‚0 £ 5‚0 square ground. The fabricated structure provides gain of 21.5dBi associated with side lobe level less than i25dB, cross polarization less than i26dB and front to back lobe ratio of more than 26dB. The measured gain variation is less than 1dB and VSWR is less than 2 over 5.725{5.875GHz ISM band. The proposed structures are good candidates for base station cellular systems, satellite systems, and point-to-point links.

https://www.jpier.org/pierc/pierc28/17.12031503.pdf

High-gain low side lobe level fabry perot cavity antenna with feed patch array

In this article, we propose efficient high gain with low side lobe level (SLL) antenna structures using parasitic patches (PPs) on multilayer superstrates. The antenna structures consist of a microstrip antenna that feeds an array of square PPs fabricated on multilayer FR4 superstrates. The patches fabricated on multilayer superstrate are suspended in air with the help of dielectric rods at integral multiple of λ0/2. The structure with 9 × 9 array of square PPs on a superstrate layer at λ0/2 provides a gain of 19 dB, which increases to 21.1 and 21.8 dB when the superstrate layer height is increased to 1.0 and 1.5 λ0, respectively. However, SLL increases with increase in superstrate height. Gain enhancement with low SLL is achieved using PPs on multilayer superstrate. The antenna with 3 × 3 and 9 × 9 array of square PPs on superstrate layers at 0.5 and 1.5 λ0, respectively provides a gain of 22.7 dB with 92% efficiency, SLL of −22.3 dB and front to back lobe ratio of more than 20 dB. Structure is designed, fabricated, and tested. The measured VSWR is <2 over 5.725–5.875-GHz frequency band. The proposed structure is an attractive solution for several wireless communication systems, such as base station cellular systems, satellite systems, and point-to-point links. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1488–1493, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26818

Avinash R. Vaidya

Papers

A Compact Dual-Band Fork-Shaped Monopole Antenna for Bluetooth and UWB Applications

Right-Hand/Left-Hand Circularly Polarized High-Gain Antennas Using Partially Reflective Surfaces

Printed Fork Shaped Dual Band Monopole Antenna for Bluetooth and UWB Applications with 5.5 GHz WLAN Band Notched Characteristics

High-gain low side lobe level fabry perot cavity antenna with feed patch array

Efficient, high gain with low side lobe level antenna structures using parasitic patches on multilayer superstrate