Microstrip Line Feeding Method, ApertureCoupled Microstrip ,FeedMethod Proximity Coupling Probe Coupling Method: Coupling of power to the microstrip patch antenna can be done by probe feeding method. The inner conductor of the probe line is connected to patch lower surface through slot in the ground plane and substrate material . To get perfect impedance matching we need to find out the location of the feed point over the antenna element. Design simplicity and input impedance adjustment through feed point positioning, makes this feeding method popular. But there are some limitations also like larger lead for thicker substrate, difficulty in soldering for array elements etc.
The use of microstrip antenna has become quit popular because of their properties such as low profile, light weight, compact . The aperturecoupled microstrip antenna first proposed by Pozar  in 1985 has a number of advantages over other feeding method involving gal- vanic contact between the antenna and feed line. The aperture is usually centered with respect to the patch where the patch has its maximum magnetic field. A sim- ple technique for changing the resonant frequencies with out resulting to a new antenna [3,4]. The idea is introduce an air gap variation between the single patch and aperturecoupled microstrip antenna. The air gap variations affect the resonant frequencies. The resonant frequencies can therefore be tuned by the variation of air gap. The band width will also increases particularly due to the increases in the height of the dielectric medium. A number of ex- periment and theoretical structure have been carried out to analyze and design aperturecoupled microstrip an- tenna. Full wave analysis using the method of moments has been used to determine the various antenna parame- ters [5-8]. A transmission line  and cavity model  have been proposed as efficiently analysis and design method. Recently an effect of the different shapes aper-
A feed line is used to excite to radiator by direct or indirect contact. Feeding techniques for Microstrip patch antennas can be classified into two main categories i.e. contacting and Non-contacting. In the contacting method, the RF power is fed directly to the radiating patch using a connecting element while in the non-contacting scheme electromagnetic field coupling is done to transfer power between the microstrip line and the radiating patch. There are many different techniques of feeding and four most popular techniques are coaxial probe feed, microstrip line, aperture coupling and proximity coupling. A comparative study of various feeding techniques is given in the table below.
Before the introduction of the Dielectric Resonator Antenna, it was used for filter applications in microwave circuits. DRA have been proposed as an alternative to the conventional conductor antennas. In high frequency application, as the frequency increases, ohmic losses in conventional antenna increases. DRA has so many advantages features such as compact size, low loss, high efficiency, light weight, ease of excitation, feeding mechanism and versatility in the shape. DRA radiate throughout their entire volume and therefore the amount of energy radiated is larger than the energy stored in their near fields. The basic DRA structure is consist of a DR element of a specific shape. DRA excited by a single feed such as a micro strip line, coplanar waveguide, aperture or coaxial cable. For the simple geometry, permittivity of the DRA decreased to achieve wider bandwidth. The most common method of feeding mechanism is the aperture –coupled arrangement. There are three basic shapes available for common design, including rectangular, cylindrical, and spherical.
In all of the cases considered here, calculations were made with 1 basis functions on both of the circular and rectangular patches for each (ρ, ϕ) or (x, y) directions and the edge condition was applied to transverse distribution for the aperture and the microstrip feed line. Increase in the number of basis functions, increases the computational time and was shown to have little eﬀects. Numerical convergence tests showed that basis functions corresponding to cavity modes with odd symmetry the so called “Orthogonal set” have very little eﬀects.
ABSTRACT: Many applications of micro strip antenna are constricted by their innate narrow bandwidth. In this paper a survey on the different feeding technique, which are micro strip line feed, coaxial plane feed, proximity coupledfeed and aperture couple feed, for wireless micro strip antenna is done. Micro strip line and coaxial probe feeds are contacting scheme, in which RF power directly to the radiating patch. Proximity and Aperturecoupled feeds are non contacting schemes, in which electromagnetic field coupling is done to transfer power between the micro strip line and the radiating patch. In this paper, a new approach is projected to design inset feed micro strip antenna with slots in it to develop the antenna bandwidth. The input impedance matching method for antenna is predominantly vital for a feed technique. The design of slotted micro strip antenna on a substrate of thickness 11mm that give wideband features is based on embedding an inset look analogous proximity L shape feed to improve bandwidth. The Method of Moments (MOM) base IE3D software with the method of moment (MOM) ensemble has been used to in the circular patch performance comparison for the improvement of the impedance bandwidth and the power radiated with slots on the same physical dimensions.
The analysis is addressed to the structure in Fig. 1(a), where a rectangular patch slot-coupled to a phase tuning microstrip line is used as single reﬂectarray element. The phase delay introduced by the element is directly related to the length of the microstrip line, which is ideally composed by two sections with respect to the aperture center. The ﬁrst section of the line is characterized by a variable length L m and represents the eﬀective phase tuning parameter, while
A structure of square-aperture antenna has been proposed in this article. The presented antenna achieved from bidirectional pattern to unidirectional pattern by integrated reflector to the antenna. The return loss, realized gain, axial ratio and radiation pattern of the antenna have been measured and presented. The antenna executes broadband CP radiation. A good axial ratio which is smaller than 3 dB in most areas of the frequency range. The square-aperture antenna with wide bandwidth and high gain is useful in practical application with gain in 8 dB.
Engineering, Universiti Sains Malaysia, Penang 14300, Malaysia Abstract—A 1 × 3 element linear array using cylindrical dielectric resonator antennas (CDRAs) is designed and presented for 802.11a WLAN system applications. The top and bottom elements of CDRA array are excited through the rectangular coupling slots etched on the ground plane, while the slots themselves are excited through the microstrip transmission line. The third element (i.e., central CDRA) is excited through the mutual coupling of two radiating elements by its sides. This mechanism enhances the bandwidth (96.1%) and gain (14.3%) as compared to aperturecoupled technique. It is also observed that the side lobe levels are reduced over the designed frequency band. Using CST microwave studio, directivity of 10.5 dBi has been achieved for operating frequency of 5.6 GHz. Designed antenna array is fabricated and tested. Simulated and measured results are in good agreement. The equivalent lumped element circuit is also designed and presented using Advanced design system (ADS) for this proposed array.
ﬁgures of merit including GBWP are presented to validate the proposed coupling aperture. The designed FSS superstrate layer is composed of two dimensional periodic array of metallic patches. It is highly reﬂective with | Γ > 0 . 9 | . Parametric analysis over FSS geometry and its height from the ground plane has been carried out. Design frequency is 2.6 GHz. Simulated and measured results are given for validation. In Section 2 the complete design of the CRA and the ray tracing formulas are presented. Section 3 covers the GBWP and other ﬁgures of merit to assess the eﬃciency of the novel coupling aperture. Parametric study of the antenna is presented in Section 4. Final design and measured results are given in Section 5.
antenna and the feed circuit, the elimination of probe reactance, easy integration of arrays and active circuits . It is shown in  that using two stacked patches can improve the bandwidth by 1 ∼ 2 times. The resonant aperture with stacked patches is also presented in . In this structure, the big aperture and thick substrate is used, with bandwidth nearly doubled that of the single patch antenna. The aperturecoupled stacked square patches with the H-shaped aperture is proposed in . The front-to-back ratio of the antenna radiation pattern is improved by using this kind of aperture, and the bandwidth of the antenna with the thick foam air layer is increased. The structure presented in [9, 10] uses the foam layer, and it could not form a strong support, and this ﬁxed structure is not easy to optimize antenna performances after the manufacture.
Figure 3 provides the spatial distribution of relative temperature along the fracture for different rock-matrix thermal conductivities in the sinusoidal fracture-matrix coupled system. It is observed from Figure 3 that when the thermal conductivity of the rock-matrix is low, the amount of heat flux diffused into the rock-matrix is low and therefore the temperature reaches steady state farther from the inlet of the fracture. It is observed from Figure 3 that for various rock-matrix thermal conductivities, the thermal diffusion into the rock-matrix using the sinusoidal model is significant compared to the parallel plate model since the sinusoidal curvature enhances heat transfer at the interface. As the thermal conductivity increases, the heat diffusion also increases, causing the thermal fronts to reach steady state nearer to the fracture inlet. It is also observed from Figure 3 that beyond a thermal conductivity of 3 W/m-K, the amount of heat transferred into the rock-matrix reduces, implying that the capacity of the rock-matrix to extract heat from the rock-fracture reduces beyond certain thermal conductivity of the rock-matrix.
To realize this polarization conversion technique, the incident field components can be decomposed into two orthogonal modes, in which one E field component is perpendicular to the receiving patch of the unit cell while the other is parallel to the patch. However, as the signal passes through the cross-shaped coupling apertures; the mode with E field parallel to the patch tends to be delayed more than the other component. Thus, due to the delaying effect, the two modes will be 90° out of phase. Hence, creates a circularly polarized mode at the back of the aperture.
W= (5) In realizing non contacting feed antenna, patches are printed on top of the first substrate, while the feedline is printed at the bottom of the second substrate. As for the ground, it is sandwiched in between of both of the substrate. Width of the feedline of the antenna is set to be 3.22mm in order to maintain characteristic impedance of 50Ω . A P-I-N diode is placed at feed branch to obtain the reconfigurability. Fig1 shows the side view of proposed antenna.
as 0.0009. The antenna structure has a bottom patch of rectangular shape over the substrate material supported by the ground plane. The top patch of the antenna is of a rectangular shape having a rectangular slot of dimensions exactly same as the dimensions of the bottom patch. The dual band antenna is fed through an aperture cut in the ground plane coupled to a 50 Ω microstrip line under the feed substrate. The side view of the antenna showing various layers organizations with placement of waveguide port is shown in Figure 1.
11. Won, K.-H., H. C. Tung, and T. W. Chiou, “Broadband dual polarized aperturecoupled patch antennas with modied H-shaped coupling slots,” IEEE Trans. on AP, Vol. 50, No. 2, 188–191, 2002. 12. Ghorbani, K. and R. B. Waterhouse, “Dual polarized wide-band aperture stacked patch antennas,” IEEE Trans. Antennas, Vol. 52, No. 8, 2171–2174, 2004.
In this type of feed technique, the radiating patch and the microstrip feed line are separated by the ground plane. Coupling between the patch and the feed line is made through a slot or an aperture in the ground plane and variations in the coupling will depend upon the size i.e. length and width of the aperture to optimize the result for wider bandwidths and better return losses. The coupling aperture is usually centered under the patch, leading to lower cross-polarization due to symmetry of the configuration. Since the ground plane separates the patch and the feed line, spurious radiation is minimized.
Abstrac: -microstrip patch antenna becomes very popular day-by-day because of its ease of analysis and fabrication, low cost, light weight, easy to feed and their attractive radiation characteristics. In order to increase bandwidth and other radiation parameters various antenna designs are made. Although patch antenna has numerous advantages, it has also some drawbacks such as restricted bandwidth, low gain and a potential decrease in radiation pattern. To overcome this issue, various feeding techniques have proposed .there are many aspects that affect the performance of the antenna like dimensions, selection of the substrate, inserting slot and also the operating frequency. This paper describes the design of microstrip patch antenna used for wimax application with operating frequency 3.75ghz. The antenna is rectangular in shape, in which rf power is fed directly to the centre radiating patch with the help of feeding techniques. Various parameters such as return loss, radiation pattern, bandwidth, gain, vswr, etc., are determined. The optimized antenna design and results are presented by using ansoft hfss. Keywords: wimax, return loss, substrate, slots, bandwidth, microstrip, vswr
To date, various single-feed CP microstrip patch antennas with miniaturized sizes have been reported [9–15]. Although asymmetric slits and cross-shaped slots can be introduced to realize miniaturization [9, 10], the measured 3-dB axial ratio (AR) bandwidths are usually narrow, which are 0.5% and 0.7%, respectively. A compact UHF RFID patch antenna was proposed based on an artiﬁcial magneto-dielectric material . The antenna has an overall size of 0 . 303 λ 0 × 0 . 303 λ 0 × 0 . 01 λ 0