ground plane in CPW feeding technique makes it easy to mount the antenna and enhance ﬂexibility. The magnetic and dielectric property of the magneto-dielectricsubstrate reduces the inﬂuence of the human body to some extent. This makes the antenna system compact and robust as additional techniques are not required for shielding as in the other design methods used to reduce the inﬂuence of human body on antenna performances as mentioned in the beginning of Section 1. The performance of antenna is better on magneto-dielectricsubstrate than the antenna on dielectricsubstrate, when being tested in close proximity to the human body (placing on wrist). Thus, antenna on the magneto-dielectricsubstrate is more suitable for the use in wearable applications in the C-band.
As mentioned above, almost all the MAs exhibit very thin vertical sizes, and the basic units of MAs also have very compact sizes compared to the operating wavelengths. However, for some speciﬁc applications (for examples, integrating into compact antennas/array or microwave integrated circuits for the purpose of reducing the coupling between adjacent elements), one needs ultra-compact embedding media so that they can be considered as fully homogenized media and will not induce side eﬀects in the whole system. Quite recently, two works are reported to achieve ultra-compact MAs by using a substrate of high dielectric constant  and a two-layer design . The former one uses a substrate with relative permittivity r = 100 which is of high-cost and diﬃcult to be fabricated in practical. Most importantly,
Abstract—In this contribution we propose the design of an inductive Frequency Selective Surface (FSS) with double resonant elements aimed at the achievement of a simple well-performing, dielectric-free, space filter screen able to separate the Ku band from the Ka band. The FSS performance is compared to that of a typical double ring FSS which major drawback is the use of a dielectricsubstrate that leads to unavoidable additional transmission losses and makes the dichroic mirror more complex with respect to a simple single perforated screen. For all applications in which the FSS is asked to be as simple as possible and the transmission losses specifications are severe, the Inductive FSS Double Resonant Elements here proposed turns out to be an interesting alternative to typical Double Ring FSS.
A printed double-T monopole antenna was proposed in . In , a compact dual-band microstrip antenna for Ku-band applications was proposed, whose dimensions are 9.50mm*10mm*0.254mm and which achieved a return loss of −23.83 dB at 12.54 GHz and −14.04 at 14.15 GHz, with a gain greater than 4 dBi. Comparatively, the proposed antenna has a limited return loss. A surface mount dual-loop antenna was proposed in . A dual-band reduced-size PIFA was proposed in . These antennas provided dual-band features to cover the 2.4/5.2 and 5.8 GHz WLAN bands. The limitations of these antennas were that they could not deliver a uniform omnidirectional radiation pattern. A low-cost microstrip-fed dual-frequency printed dipole antenna was proposed for wireless communications in . This antenna’s size is large and its bandwidth is limited. In , a printed dual-band dipole antenna with U-slot arms was proposed for the 2.4/5.2 GHz WLAN operation. The 370 MHz bandwidth of that antenna is insufficient to cover the desired band. In , a dual broadband design of a rectangular slot antenna was proposed for 2.4 and 5 GHz wireless communications. The antenna dimension is 75mm*75mm, the substrate permittivity is 4.70, and the thickness is 0.80 mm. In , a dual-band WLAN dipole antenna using an internal matching circuit was proposed. The antenna dimensions are 12mm*45mm and FR4 is used as the dielectricsubstrate material to cover the desired bands.
For planar antennas analyzed using the spectral domain approach, a stationary phase method is usually used to obtain the radiation patterns [10,13]. This method gives convenient and useful results except for points close to the dielectricsubstrate. In fact, patterns calculated in this way appear to have nulls at the air-dielectric interface since the substrate is assumed to be infinite. In practice, the H-plane patterns of strips printed on electrically thin ungrounded dielectric substrates of finite size show no nulls there. If strips are not printed close to the dielectric edge, the strip currents obtained via Eq. (7) would be accurate even though the dielectric is of infinite size, and accurate radiation patterns are obtained by assuming the strips radiate into free space. In this way the contribution of the polarization currents is not taken into account, but they are
Now days, this world is based on technology. The new research & development of wireless communication systems has the main region of this changed era. To fulfill the demand of these, invention of compact microstrip antennas with high gain and wideband operating frequencies has developed. Microstrip patch antenna has many salient features like small size, low profile, light weight, simple realization process and low manufacturing cost. With so many advantages, MSPA have some disadvantages also, such as narrow bandwidth etc. To improve the performance & Enhancement of the performance of such antennas &to meet the demand of bandwidth is necessary . There are many ways via them, we can improve the bandwidth of antennas, including of the substrate material, via different ways with low dielectricsubstrate, slotted patch antenna, the use of various impedance matching and feeding techniques, with the use of absorbers & resonators [2-8].
A Microstrip patch antenna consists of a radiating patch on one side of a dielectricsubstrate which has a ground plane on the other side as shown in Figure: 1. the patch is generally made of conducting material such as copper or gold and can take any possible shape. The radiating patch and the feed lines are usually photo etched on the dielectricsubstrate. Microstrip antennas, as shown in Figure 1, consist of a very thin (t _ λ 0 , where λ 0 is the free-space wavelength) metallic
This paper presents new form of artificial neural network description (ANN) for the estimation of bandwidth of a coaxial feed rectangular microstrip patch antenna. The results obtained using ANNs are compared with the IE3Dsimulation and found quite satisfactory. The designed antenna operates in the frequency range of 1.90 to 2.27 GHz and 3.052 to 3.570 GHz. The antenna is designed using air as a dielectricsubstrate between the ground plane and patch and simulated on the Zeland IE3D software and the results are compared with neural network tool of matlab.
Antenna is part of a transmitting or receiving system that is designed to radiate or receive electromagnetic waves. Microstrip antenna is only one such type of antenna. A microstrip device in its simplest form is a sandwich of two parallel conducting layers separated by a single thin dielectricsubstrate. The upper conductor is thin metallic patch (usually Copper) which is a small fraction of a wavelength. The lower conductor is a ground plane which should be infinite theoretically. The patch and ground plane are separated by a dielectricsubstrate which is usually nonmagnetic. Here the dielectric constant of the substrate ranges from 2.2 to 3.0. The patch can assume any shape such as rectangular, circular, triangular, elliptical, helical, circular ring etc. Microstrip antenna elements radiate efficiently as devices on microstrip printed circuit boards. Microstrip patch antenna consists of a radiating patch on one side of a dielectricsubstrate with a continuous metal layer bonded to the opposite side of the substrate which forms a ground plane. The patch is generally made of conducting material such as copper or gold and can take any possible shape. A patch antenna is a narrowband, wide-beam antenna fabricated by photo etching the antenna element pattern in metal trace on the dielectricsubstrate.
411 Deschamps first proposed the microstrip concept through the use of microstrip feed lines to feed an array of printed antenna elements. The idea was further developed by Robert E. Munson (now in Microwave Hall of Fame) and John Q. Howell. Several other works done on microstrip antennas discussed both the wraparound microstrip antenna and the rectangular patch which are the most common types of microstrip antenna [6, 7]. Research is still on-going to improve microstrip antennas. Microstrip patch antenna is seen as one of the most useful antennas at microwave frequencies (f>1GHz), consisting of a metal patch on top of a grounded dielectricsubstrate.
Abstract—A circular microstrip patch antenna design is proposed for applications that require suppression of surface waves and lateral waves. The proposed design is composed of a circular patch loaded with a single shorting pin on a grounded inhomogeneous dielectricsubstrate with a desired eﬀective permittivity. The modal equation for the normalized resonance frequency of this design is solved numerically. Simulated and measured radiation patterns show that a good reduction of surface waves and lateral waves is achieved. A comparison between the present work and an alternative design in the literature is presented in this paper. The proposed design could ﬁnd applications in large patch antenna arrays where mutual coupling needs to be eliminated and in high-precision global positioning system receivers where multipath interfering signals associated with low-angle reﬂection aﬀect position accuracy.
Abstract: This paper presents the study of 5.8 GHz frequency selective surface (FSS) acts as a band stop to eliminate unwanted radiation signal at 5.8GHz. The FSS was designed using computer simulation technology (CST) Microwave Studio software. The paper shows the comparison of square loop, octagon loop and hexagon loop of Band stop FSS (BSFSS) performance at 5.8 GHz. Besides, the BSFSS design using four different type of dielectricsubstrate such as FR-4, TLY-5, Roger RT5870 and Roger RT5880 were compared. The results obviously show that the Rogers RY5880 has the attenuation -44.72 dB. The fabricated FSS were measured by using free space technique with two horn antennas connected to performance network analyzer (PNA). The measured and simulated results were compared. The results show that the square loop FSS structure have the better attenuation - 26.76 dB (simulated) and -38.34 dB (measured) at 5.8 GHz.
A RMPA has the reward of low cost, diminutive weight, and low profile planar pattern. While the RMPA have originated wide diversity of function areas, unlike techniques are probable to get better the limited bandwidth. A straightforward approach to get better the bandwidth is rising the thickness of the substrate at the bottom of the microstrip patch . However, boundaries at rest survive on the ability to productively feed the patch on a thick substrate and the radiation efficiency can disgrace with increasing substrate thickness  and . It was originate appropriate to select a thin dielectricsubstrate with low dielectric constant permits to diminish the size and also false radiation as surface wave, and higher bandwidth, superior efficiency and low power loss  and . It was also established antenna intend structure extent and Feed positions are in performance the significant role to improve the Band-width and get better the antenna efficiency.
Microstrip antenna was a simple antenna that consists of radiated patch component, dielectricsubstrate and ground plane. The radiated patch and ground plane is a thin layer of copper or gold which is good conductor. Each dielectricsubstrate has own dielectric permittivity value. This permittivity will influence the size of the antenna. Microstrip antenna is a low profile antenna, conformable to planar and non-planar surface, simple and inexpensive to manufacture using modern printed-circuit technology. They have several advantages light weight, small dimension, cheap, conformability and easily to integrate with other circuit make it is chosen in many applications .
The simplest patch antenna consists of a rectangular metallic patch on one side of a dielectricsubstrate and a ground plane on the other side of the dielectricsubstrate. The thickness of the metals of the patch and ground plane, t, is very small compared to the wavelength (t<< λ). However, the metal thickness, t, must be at least a few times larger than the skin depth. If the metal thickness is smaller than skin depth Ohmic losses in the patch and the ground plane drastically reduce the radiation efficiency of the antenna. Substrate thickness h, and its dielectric constant εr, play important roles in the radiation parameters of the antenna. Substrate thicknesses are usually in the range of 0.002λ0 < h < 0.1λ0, where λ0is the wavelength in free space. Substratedielectric constants usually range from 2.2 <εr< 12. 
Ultra wideband (UWB) system has been considered and almost recommended for applications in wireless communication due to its capability to provide high speed. A microstrip patch antenna consist of a radiating patch which is placed above the dielectricsubstrate and a ground plane is placed on the other side of dielectricsubstrate Microstrip antennas having several advantages such as light weight, low cost, thin profile, conformal to a shaped surface so it can be used in several applications As in aircraft, satellite and wireless communication.
small weight, low profile and ease of manufacture. However, the main limiting factor in implementing these antennas in many applications is their low impedance bandwidth. One popularly used technique of enhancing the bandwidth is to use suspended microstrip, which in view of the air layer next to the ground plane, offers improved efficiency. The aim of this paper is to study the bandwidth and radiation characteristics of suspended microstrip rectangular patch antennas with dielectric. Using this technique a single layer suspended microstrip antenna which offers 80MHz, 200MHz and 100MHZ (S11 < ¡10 dB) impedance bandwidth has been reported in this paper.
As an interface between transmitter/receiver and free space, antennas are essential part of any communication system (satellites, radars, aviation, medical applications etc.). Microstrip patch antenna is formed when a substrate material is placed between two metal plates. The dimension of microstrip patch are very less i.e., in the order of few mm to cm, Moreover microstrip patch antennas can be easily integrated with the VLSI circuit boards. This indirectly increases the package density and reduces the power consumption. The key features of a Microstrip patch antenna are ease of fabrication, light weight, low cost . These advantages of Microstrip antennas make them popular in many wireless communication applications such as telemetry and communications, aviation, naval communications, automatic guidance of intelligent weaponry, radar, GPS systems. The most serious problem of patch antenna is its narrow bandwidth . Therefore there is a need to enhance the bandwidth of microstrip antenna for WLAN application.
In order to further explore the advantages of empty substrate transmission lines, partially dielectric- filled ESIW waveguide and ESIW bandpass filter are presented. By utilizing empty substrate integrated waveguide (ESIW) structure and dielectric loaded filter technology, the possibility of controlling the impedance of waveguide without the need to modify the cutoﬀ frequency is increased dramatically beside potential to reduce the size of ESIW. The designed filter and dielectric-filled ESIW are aimed to work at millimetres applications band. Bandpass filter ESIW model is studied by characterizing its parameters. The transmission line is modeled, which includes β and attenuation α calculations and measurements. This filter is designed and measured carefully to ensure the coupling between dielectric planes to create resonators suitable for millimetre applications where good transition technique is utilized to connect ESIW filter to microstrip for the planar substrate.
Microstrip antennas are most popular because of its numerous advantages in wireless communication systems that typically require antennas with light weight, low volume, easy to fabricate, low cost, and planar configuration which can be easily made conformal to hot surface . Basic geometries of these antennas suffer from a narrow bandwidth, which is of the order of a few percent of the operational frequency. The bandwidth can be increased by various techniques like the use of thick substrate and low dielectric constant, multiple-resonator technique in either coplanar [2, 3] or stacked configurations . Various feeding schemes are given in many standard books . Many of these feeding techniques can improve the bandwidth, but provide asymmetry in radiation pattern. With considering all these effects, the use of a capacitive feeding strip with coaxial feeding probe is proved to increase the bandwidth [5, 6]. A rectangular microstrip antenna with a proposed rectangular strip provides the improved bandwidth with nearly symmetric radiation pattern.