Proximity Feeding Technique Research Articles

Polarization-Agile Circular Polarized Antenna Based on Proximity Feeding Technique

In this letter, the design and experimental validation of polarization-agile circular polarized antenna are presented. The antenna is comprised of a patch antenna with truncated slits and two proximity feedlines. The antenna produces a vertical linear polarized wave when it is fed by a proximity feedline. Horizontal linear polarized wave is then generated by applying a potential difference between two proximity feedlines. The quadrature phase difference between two orthogonal polarized waves is created by adding truncated slits into the patch antenna. By swapping the polarity of the proximity feedlines, polarization sense can be changed. The distributed circuit model is presented to describe the working mechanism of the antenna. Patch antenna with circular polarization agility is then validated through passive-type and active-type switching circuits. The measured axial ratio bandwidth is 4.085% (100 MHz), and the fractional impedance bandwidth is greater than 7% for the left-handed and right-handed circular polarized radiations.

Optimization of Directivity and Gain Performances on Circular Patch Antenna Design for 2.4 GHz Applications

In this paper, simulation and optimization analysis on circular patch antenna for 2.4GHz is presented. The performance that been specifically focused in this analysis is the improvement of the directivity and gain of the circular patch antenna design. Basically, the objective of this analysis is to compare the circular patch antenna of a single form with 1x2 antenna array formation. These antennas are designed with the proximity feeding technique. From the previous literature and findings, the optimization works of array arrangement have been proven will improve the directivity and gain performances. In this study, the array arrangement with proximity feeding technique of optimization work to improve the directivity and gain of a circular patch antenna has been explored. Comparison of a single and array of micro strip circular patch with proximity feeding technique as the FR-4 is the substrates with permittivity equal to 3.95 is presented. Based on the results, 1x2 array arrangements enhance the directivity and gain output compared to a single form circular patch antenna design. The directivity performance improves 28% and gain has been improved by 47% after optimization. The findings show that the array elements with proximity feeding technique design offer to improve and enhance the directivity and gain performances of an antenna.

Series-Fed Dual-Polarized Single-Layer Linear Patch Array With High Polarization Purity

In this letter, a novel dual-polarized 1 × 4 patch array using proximity feed technique is presented. The proposed single-layer antenna consists of four square patch elements, two short-terminated parallel coupled microstrip lines, and a rat-race incorporated in the feed network. The patches are placed at the inner space between the two parallel microstrip feedlines. Horizontal and vertical polarizations of the patch array are excited by the even and odd modes of the two microstrip lines, respectively. The rat-race structure is used to provide in-phase and 180° out-of-phase feeds for the two modes. A prototype operating at 3.5 GHz is fabricated and measured. The measured overlapping bandwidth of the two ports is 81 MHz, also with port isolation higher than 40 dB. Owing to the symmetry of the structure and balanced excitations, the measured cross polarizations are all below -29 dB in E- and H-planes.

Optimized broadband and dual-band printed slot antennas for future millimeter wave mobile communication

In this paper, a broadband and a dual-band printed slot antennas for the future millimeter wave mobile network communication are proposed. The antennas are designed for Ka-band frequency of operation. The basic antenna design consists of a circular radiating patch that is placed non-concentrically inside a circular slot etched off the ground plane. Matching between a radiating patch and the 50Ω microstrip line is manipulated through a proximity-feed technique. The simulated antenna prototype – I and prototype – II are fabricated and successfully measured. The results indicate that the proposed antenna prototype – I yields the broadband impedance bandwidth >20GHz (from 20 to >40GHz) define by S11<−10dB that covers two important millimeter wave frequency bands (28/38GHz). To reduce the interference between the different applications operating around these frequency bands, the L-shaped slot is etched off in prototype – II feedline to create a notched band of 30–35GHz. The measured results show that the designed antenna has dual-band at 28 and 38GHz with a band notched at 33GHz. The low profile/cost broadband antenna (prototype – I) and dual-band antenna (prototype – II) has the measured gain upto 5.30dBi and 5.6dBi with the estimated radiation efficiency of 93% and 94%, respectively. The simulations are performed using industry-standard software CST MWS and HFSS. The measurements are in a good match with the simulated results.

Circular-polarized Proximity-fed Tip-truncated Triangular Switchable Array for Land Vehicle Mobile System

This paper proposes a compact, circularly polarized (CP), tip-truncated, triangular patch array developed for a land vehicle mobile system for mobile satellite communications. The array is constructed by three patches so that its beam pattern can be switched in three 120°-coverage beams in the azimuth plane with minimum gain requirement at a fixed point of the elevation angle. With this pattern, data communications with a large geostationary satellite can be achieved. The targeted gain is set to be 5 dBic at 48° of the looking angle from the satellite in the Kanto area. The patches are fed with a proximity feed technique because of its simplicity and easier installation on the vehicle. The array performance is numerically analyzed with the method of moment to clarify the array characteristics. Measurement results are provided to validate the simulated results. The results show that the array meets the specifications at the targeted looking angle of 48° when the gain is more than 5-dBic for each three-selectable beams in the azimuth plane.

Analysis of Broadband L-probe fed Microstrip Antennas

suspended microstrip antenna on thicker substrate is realized by using non-contact L-probe feeding technique. The guidelines for selecting total L-probe length are not available in the reported literature. In this paper, an analysis of broadband L-probe fed variations of microstrip antenna like, circular microstrip antenna, annular ring microstrip antenna, rectangular microstrip antenna, E-shaped microstrip antenna and half E-shaped microstrip antenna, is presented. It was observed that, total L-probe feed length nearly equals quarter wavelength at the resonance frequency of equivalent patch. Further using this quarter wavelength approximation, L-probe fed rectangular and circular microstrip antennas were re- designed at different frequencies which results into the broadband response with formation of loop inside the VSWR = 2 circle. The comparison between two non-contact feeding techniques of microstrip antenna, namely proximity feed and L-probe feed is presented. The two have similar performance in terms of bandwidth and radiation pattern, with proximity feeding technique to be the simplest method to be implemented in thicker substrates. Keyword microstrip antenna, Circular microstrip antenna, Annular ring microstrip antenna, E-shaped microstrip antenna, Broadband microstrip antenna, L-probe feed upon the ratio of vertical strip length to its horizontal length for the given patch substrate thickness. The design guidelines for properly selecting the strip vertical and horizontal lengths are not reported in the available literature. In this paper, various reported broadband designs of L-probe fed RMSA, U- slot cut CMSA, annular ring MSA, E-shaped MSA and half E-shaped MSAs are discussed. Further using their optimized designs the formulation for total L-probe length in terms of operating wavelength of the resonance frequency of the radiating patch is proposed. The total L-probe length was found to be around quarter wave in length at the patch resonance frequency. Using this approximation, RMSAs and CMSAs were re-designed at different frequencies. This results in broader BW with formation of loop in the impedance locus inside the VSWR = 2 circle. For RMSA, the comparison between the non-contact proximity feeding and L-probe feeding technique is presented. It was observed that in terms of operating BW and radiation pattern characteristics, both these techniques yields nearly the same performance, however as against L-probe feeding, the proximity feeding is simpler to implement especially in thicker substrates. The proposed study was carried out using IE3D software (18) and to validate the simulated results, measurements were carried out using finite square ground plane of side length 40 cm. The input impedance response was measured using R & S vector network analyzer.

Proximity fed Broadband Microstrip Antennas

broadband microstrip antenna is realized by fabricating the patch on lower dielectric constant thicker substrate in conjunction with proximity feeding technique. Using thicker substrates, a formulation for an edge extension length and design guidelines for strip dimensions in proximity fed broadband antennas, are not available. In this paper, first by designing suspended rectangular and circular microstrip antennas on different substrate thickness and at various frequencies in 800 to 6000 MHz frequency band, graphs for an edge extension length are developed. Using them an edge extension length at given frequency and substrate thickness is calculated. The suspended patches were further designed using edge extension length graphs which give closer result with the desired frequency. Further by using proposed equations, proximity fed microstrip antennas were optimized at various frequencies in 800 to 6000 MHz frequency band. Using these optimized designs, a formulation for coupling strip parameters is proposed. By using proposed formulations for edge extension length and strip parameters, proximity fed antennas were re-designed at different frequencies in 800 to 6000 MHz frequency band. In all the configurations, broadband response with formation of loop inside VSWR = 2 circle is obtained. Also by using the proposed formulation, design procedure for proximity fed U-slot cut rectangular microstrip antenna is explained. The U-slot cut antenna gives bandwidth of more than 450 MHz at center frequency of around 1000 MHz. The proposed formulations can be used to design broadband antennas using thicker substrate at any given frequency. Keywordsctangular microstrip antenna, Circular Microstrip Antenna, Equilateral triangular microstrip antenna, Edge extension length, Proximity feeding, Broadband microstrip antenna coupling strip which is either placed below or in the plane of the patch. A larger BW is realized due to electromagnetic coupling between the patch mode and the strip. This method yields broader BW for thickness more than 0.060. The BW of MSA is also increased by cutting a slot inside the patch (4 - 8). Further increase in the BW of slot cut MSA is realized by using proximity feeding technique (9). In proximity feeding method, for the given patch and strip substrate thickness, design parameters are, the strip dimensions and its position below or in the plane of the patch. In the available literature on proximity feeding, the design guidelines for given substrate thickness and operating frequency are not available. In this paper, design formulations for broadband proximity fed MSAs on thicker substrates are proposed. First by designing rectangular MSA (RMSA) and circular MSA (CMSA) at a given frequency and for different substrate thickness in 800 to 6000 MHz frequency band, plots for an edge extension length against substrate thickness are developed. Using them an edge extension length at any given frequency and substrate thickness is calculated. By using the proposed graphs, patch was re-designed at different frequencies in the above frequency band. It gives patch resonance frequency at nearly the same desired value with an error less than 2%. Further broadband proximity fed RMSA, CMSA and equilateral triangular MSA (ETMSA) were designed at different frequencies in the 800 to 6000 MHz frequency band. Using their optimum designs, the formulations for strip dimensions and its position below the patch for the given patch substrate thickness is proposed. Using edge extensions graphs and the formulation for strip dimensions, proximity fed RMSA, CMSA and ETMSA were re-designed at different frequencies in 800 to 6000 MHz frequency band. A broadband response with the formation of loop inside the VSWR = 2 circle is obtained. Using proximity fed formulations, a detail design procedure for proximity fed U-slot cut RMSA is also presented. It gives broadband response with BW of more than 450 MHz (>45%). The above study was carried out using IE3D software followed by experimental verifications (10). In IE3D simulations an infinite ground plane was used. In measurements the antennas were fabricated using the copper plate having finite thickness and were supported in air using the foam spacer support placed towards the antenna corners. The antenna was fed using N-type connector of 0.32 cm inner wire diameter. At all the frequencies, measurements were carried out using R & S vector network analyzer (ZVH 8 model) using finite square ground plane of side length 100 cm. This larger ground plane simulates the effect of infinite ground plane. The radiation pattern was measured in minimum reflection surroundings with required minimum far field distance between reference antenna and antenna under test (11). The antenna gain was measured using three antenna method (11). The proposed

Broadband Proximity-Fed Modified Rectangular Microstrip Antennas

The bandwidth of a microstrip antenna is increased by using a thicker and lower-dielectric-constant substrate, or by using multi-resonator gap-coupled and stacked configurations, or by cutting a resonant slot inside the patch. However, with all of these methods, the bandwidth of the antenna is limited by the probe's inductance for substrate thicknesses greater than 0.06λ0 to 0.07λ0. For substrate thicknesses larger than 0.07λ0, the bandwidth of the antenna can be increased by using a proximity-feeding method. In this paper, by using a combination of the proximity feeding technique and a thicker substrate, various broadband configurations of gap-coupled rectangular microstrip antennas, E-shaped and half-E-shaped microstrip antennas, and gap-coupled half-E-shaped microstrip antennas are proposed. All of these configurations give bandwidths in excess of 350 MHz (>;35% ), with gains of more than 7 dBi, in the 800 to 1200 MHz frequency band, with a broadside radiation pattern.