Spectral domain analysis of circularly polarized rectangular patch antennas with a dielectric superstrate

A circular polarization (CP) patch antenna is proposed for the first time in this article. The proposed antenna is developed based on a patch antenna combined with one row of diagonal periodic metallic via holes. By optimizing the location of the periodic metallic via holes, two orthogonal waves with 90° phase difference are excited using single feed and a CP patch antenna is obtained. A CP antenna is designed based on the proposed structure and simulated by Ansoft HFSS. The designed CP antenna is fabricated and measured. The measured results present return loss |S11| > 10 dB from 10.4 to 11.6 GHz. The radiation pattern is also measured, and it exhibits good circular polarization property with 3-dB axial ratio (AR) of 1.2 dB and gain of 4.02 dBic. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett1100, 2013; 1097 this 1100 online at wileyonlinelibrary.com. DOI 10.1002/mop.27529

A microstrip-fed inverted patch antenna with linear or circular polarization, holding an air layer between the patch and the ground, is proposed to realize the broad-band patch antenna printed over a very thin substrate at the low-cost level. For a linearly polarized type, its input characteristics are rigorously characterized by a novel spectral-domain moment method. Compared with the conventional patch antenna, its bandwidth is found to be sharply improved, numerically from 0.246% to 3.48%, and experimentally from 0.290% to 2.95% for a patch antenna matched by a quarter-wavelength transformer. For a circularly polarized type, its electrical characteristics are efficiently designed by the cavity model approach based on the simulated input resistance of the linearly polarized patch antennas. Its measured axial ratio (AR) is found to be lower than -0.5 dB at the designated resonant frequency (f/sub 0/=2.0 GHz), while its AR bandwidth is measured to be about 1.0%. Moreover, all the measured parameters are found to be in excellent good agreement with the simulations at the frequency shifts less than 2.0% and at the measured return losses less than -15.0 dB.

The problem of an aperture-coupled patch antenna is studied using the spectral domain technique. The general case of a slot inclined to both the feedline and the patch is considered. The equivalent circuit for the structure is obtained and the effects of various parameters, such as slot dimensions and inclination on the resonant frequency and on the input impedance, are studied. Comparison between theory and measurement shows good agreement. The analysis could be useful in designing antennas for dual frequency operation or for circular polarisation where inclined slots could be used.

A modern approach to an established technique is investigated for the electronic control of polarisation of microstrip patch antennas. The control is achieved by placing micro-electromechanical switches (MEMS) at appropriate locations in a patch antenna. The microwave MEMS are used to switch between open and short circuit conditions that allow reconfiguration of the modal fields. Changing the number and location of short circuit field regions changes the radiated field polarisation from linear horizontal to vertical, right hand circular or left hand polarisation. All of the polarisation states are obtained without changing the frequency of operation, input impedance or radiation pattern of the patch antenna. The antenna is fed with a single external feed network.

A compact single asymmetric coplanar waveguide feed (ACPW‐fed) dual circularly polarized microstrip antenna that operates at 1.8, 3.9, and 5.2 GHz in the entire operating frequency band 600 MHz–6 GHz for the radar detection of the improvised explosive devices (IEDs) carried by a person is introduced. The proposed novel quasi‐omnidirectional antenna consists of single sided rectangular ring microstrip patch antenna. L‐shaped slots are etched at the two opposite corners of the rectangular ring, introducing new resonance and circular polarization waves at the mid and upper bands, respectively. The achieved dual half‐rectangular ring patch antenna (DHRR‐patch) is loaded with strips of various shapes delicately placed at the center of the radiator, providing new resonance at the upper band and the improvement of the CP features. The matching technique designed based on CPW 50 Ω microstrip transmission line combined with the dual broad band matching techniques through quarter‐wave transformer in conjunction with open stubs and distributed lumped element method constitutes the novelty of the study. Based on quasi‐TEM mn (q‐TEM mn ) mode, ACPW‐fed and CP‐slots are employed to generate CP radiations at the q‐TEM 11 and q‐TEM 21 modes, respectively, while the ground plane width is optimized to enhance axial ratio bandwidth (AR‐BW). Input impedance and radiation pattern calculations of the conventional structure using transmission line and cavity model‐based q‐TEM 01 mode are conducted, respectively. Numerical experiments of the studied monolayer antenna are carried out using Advanced Design System (ADS) Version 2009 environment software employing internal one‐port option to excite the antenna. The prototype of the proposed antenna with a compact dimension (0.27 λ g × 0.38 λ g × 0.02 λ g at 1.8 GHz where λ g is the guided wavelength of the q‐TEM 01 mode) is fabricated on high loss laminate FR4 substrate of volume 43 × 38 × 1.6 (mm 3 ) and relative dielectric constant of 4.4 with simple laboratory‐based traditional printed circuit board (PCB) etching process. Measurement results show a fractional impedance bandwidth (FIBW) of 11.1%, 5.9%, and 7.1%, axial ratio (AR) of 4.6, 2.2, and 0.5 dB, and peak gain of 3.7, 4.7, and 6.1 dBic at 1.8, 4.0, and 5.2 GHz, respectively, demonstrating its suitability for IED detection applications. To verify the efficiency of the proposed model, measured results are compared with the simulated results and good agreement has been established.

This paper presents the design of patch antennas for possible use in the 5 GHz-band HIPERLAN and NII wireless local area networking systems. In order to communicate with a base station or a peripheral unit, the radiation pattern of these antennas should be symmetrical in azimuth with the minimum in the zenith direction. A circular patch operating in the TM/sub 02/ mode can be used to obtain such a radiation pattern. An aperture coupling and a coaxial probe are investigated as possible feeding mechanisms for the patch antenna operating in the TM/sub 02/ mode. A full-wave analysis method is used to predict the two antennas performance in terms of return loss, input impedance, gain and radiation pattern. The effects of higher order modes and a finite ground plane on the radiation pattern are discussed.

The demand for using wireless communication systems which make mass memory information and high speed contact possible has increased, recently. A built-in microwave antenna is necessary for such systems. This paper presents the design of an aperture coupled modified cross-slot microstrip patch antenna with four new slots generating a circular polarization and using a microstrip substrate produced by plane type printing technology which meets such a demand. The antenna is characterized by small size, light weight, and multifunctional operation. As a result, a return loss of -40 dB at the center frequency 5.84 GHz was obtained by simulation of the ISM band with an operation frequency 5.8 GHz and a return loss of -37 dB at 5.79 GHz by actual measurement, suggesting that the match between the feeding line and radiation patch is better than the existing aperture coupled cross slot microstrip antenna, and the axial ratio is also good.

A novel design method of harmonic suppression and size reduction of a circularly polarized (CP) microstrip patch antenna (MPA) is presented by using nondegenerate modes. Based on a circular MPA, a pair of orthogonal modes could be generated between these undesired resonant modes. Then, by loading the shorting pins in a quarter fan-shaped patch, all these undesirable high-order modes could be suppressed between them. After that, the higher and lower modes are moved closer to each other by cutting a long slot at the angle bisector of the fan-shaped patch, providing the CP radiation pattern. Finally, a prototype of this proposed antenna has been designed, produced, and measured to verify the design concept. The experimental results show that the proposed antenna has an impedance bandwidth of 286 MHz (13 774–14 060 MHz), axial ratio bandwidth of 80 MHz (13 900–13 980 MHz), and a left-hand CP peak gain of around 4.8 dBi. Most importantly, the CP antenna has realized the harmonic suppression of about 15 GHz, which has an obvious advantage as compared to the traditional CP MPA. Moreover, the antenna still holds the primary low-profile, single-radiator, simple structure, and high-efficiency simultaneously.

In this paper, we present the development of a novel class of reconfigurable microstrip antennas: patch antenna with liquid metal tuning slots. By manipulating liquid metal in 3D printed microfluidics bounded on top of a slotted patch antenna, various attractive reconfigurable characteristics can be achieved with simple patch topologies. Two representative designs are presented to demonstrate the capabilities of patch antenna with liquid metal tuning slots: a frequency reconfigurable patch antenna with frequency tuning bandwidth of 70% and instantaneous bandwidth of 2 %; and a polarization reconfigurable patch antenna with right-hand circular polarization (RHCP), left-hand circular polarization (LHCP), and linear polarization (LP) with arbitrary orientation in x-y plane. The process for prototyping patch antenna with liquid metal tuning slots is also presented, which successfully minimized the skin residues. Measurement has been performed with good agreement to the simulations. We believe that this design and prototype strategy can be applied to other potential topologies with various reconfigurable functionalities.

The pattern synthesis based on the spectral Green's functions for multi-layered perforated dielectric loaded patch antenna is presented. It is conducted by optimising the dielectric superstrate parameters, i.e. relative permittivity (εr) and thickness. To solve the problem of the optimised εr unavailable from market, perforated dielectric superstrate (PDS) is utilised. The equivalence between PDS and homogeneous dielectric superstrate (HDS) in spectral domain is investigated and the effective relative permittivity (εreff) of PDS is studied. Moreover, by introducing εreff, the general optimisation procedure for HDS loaded antenna is also applicable for PDS loaded antenna, which reduces the computational cost significantly. To validate their method, a two-layer PDS loaded patch antenna with E/H beamwidth equalisation was designed, fabricated and measured. Simulations and measurements show that the synthesised antenna has satisfactory performances over the ITU-RS.1068-1994 band from 13.75 to 14 GHz. The half 10 dB E/H beamwidths of 19°/20°, −27 dB cross polarisation and −15.5 dB side lobe level have been achieved.

This article presents a set of CAD oriented closed form expressions to predict accurately the effect of radome (superstrate) on resonant frequency, input impedance, bandwidth, and gain of rectangular patch antenna. Merits of this model include low computation cost and mathematical simplicity. The numerical values obtained with the present method are compared with experimental and different theoretical values. The accuracy of this model is verified with electromagnetic software (HFSS) computation and with the experimental values. The present model shows very close agreements with the experimental and software computation values compared to the other models for wide range of thickness and permittivity of substrates and superstrates. This model is directly applicable for the integration of patch antennas beneath plastic covers or protective superstrates in portable wireless equipment and aircraft radome. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:883–893, 2014

This paper is presentation of designed different diodes loaded active model dissimilar geometries of micro strip patch antennas. As known, mikrostrip patch antennas have complex impedance and its impedance changes with frequency. Because of this, imaginer part of micro strip patch antennas is minimized by effect of diodes having capacitive reactance thus maximum power radiating is occurred. The aim of this project is to present different diodes loaded patch antenna for ISM 2.4 Ghz and to indicate active antenna performance according to influence of locations and dc biasing of diodes then to compare the antenna parameters of passive models. Besides, this project is used three types of diodes which are schottky Barrier diodes, silicon variable capacitance diode and tuner diode and four diodes whose are bas70, bas83, bb619 and bb721. The simulation programmer is AWR Design Environment Microwave Office 2007 (MWO) whose analysis meted is moment (Mom). Finally, the antennas that are projected are ready condition for LAN application or wireless RF receiver-transmitter systems. Return loss of designed antennas are between -25.54 dB and -36.17 dB. Gain does not change a lot but results of VSWR and Input impedance is satisfactory when comparing the passive model's results.

Miniaturization is one of the prime motives in modern communication systems and can be achieved through size reduction of both components and their packages. Whereas passive components are fairly insensitive to packaging, this is certainly not the case for antennas, as the package is located in the nearfield. The paper focuses on the effects of the casing on the radiation characteristics of a miniaturized patch antenna for circular polarization. Different scenarios involving metallic and dielectric casings with planar dielectric overlays are investigated. A circularly polarized microstrip patch antenna has been designed and investigated with respect to effects introduced by the casing. It is found that a metallic casing severely influences the gain and the axial-ratio bandwidth. It also changes the direction of minimum axial ratio. By placing the patch asymmetrically in the casing, the minimum axial ratio can be improved. A dielectric casing has minimal effect on the radiation properties.

In this paper, a novel method to enhance axial ratio bandwidth of circularly polarized (CP) patch antenna using artificial magnetic conductor (AMC) structures with LTCC technology at Ka-band is proposed. In order to improve the axial ratio bandwidth, the traditional PEC plane is replaced by an AMC plane. The AMC is composed of periodic square unit cells with truncated opposite corners. The AMC structure and the antenna are simulated using a full-wave solver and the results show a 10 dB return loss bandwidth of 30% and a 3 dB axial ratio bandwidth of 12.7%, and gain is around 7.5 dB within this band, which compared with the traditional corner-cut square circular polarization patch antenna, the axial ratio bandwidth of proposed antenna increased by 9.5%.

Modern wireless communication devices desire antennas with enhanced performance and low profile. EBG (Electromagnetic Band Gap) surfaces are artificially engineered to improve antenna performance. The performance of a square patch antenna over a 2D-Mushroom EBG ground plane is investigated by comparing patch antenna with conventional ground plane. In this paper, a circular polarized patch antenna resonating at 2.4 GHz, for ISM band applications is designed, fabricated and tested. The antenna is a square patch with truncated edges, exhibiting Right Hand Circular Polarization (RHCP). Circular polarization is crucial to eliminate antenna orientation requirements. Band gap nature of mushroom EBG unit cells are investigated and loaded between patch and the ground plane to eliminate back lobe and improve antenna performance. The mushroom EBG is designed to resonate at 2.45 GHz, with a forbidden band gap of 450 MHz, in-phase reflection band gap of 390 MHz and a high impedance of 3475 Ω at resonance. The introduction of EBG ground plane enhanced the gain to 5.35 dB with an excellent axial ratio at resonance and an operating bandwidth of 7%, with reduction in patch dimensions. The design was simulated in HFSS and tested using VNA after fabrication, resulting in highly correlated results.