square slot

In this paper, a novel CPW-fed CP square slot antenna with excellent CP and impedance bandwidth is presented. In the proposed antenna, a lightening-shaped feedline is protruded from the center signal strip of the feeding CPW, and a tuning stub are embedded in the feeding structure. In addition, two symmetrical F-shaped slits embedded in the opposite corners of ground plane are constructed, which can introduce more resonant branches. Novel symmetrical F- shaped slits introduce more resonant branches. As a result, the axial ratio bandwidth of the proposed antenna has been further enhanced compared with all the above-mentioned antennas proposed in [11]. Moreover, the antenna can be easily fabricated on PCB. Measurement results are in very good agreements with the simulations illustrating that the optimum 3-dB AR bandwidth can reach 51.7%, which is completely covered by the VSWR ≤ 2 impedance bandwidth.

A pair of stubs or notches with different dimensions is firstly introduced in Case 1 and 2, in which one stub (notch) is designed to obtained low CP AR and another stub (notch) is adopted to affect the impedance bandwidth. Though the positions of the stubs and notches in Case 1 and 2 are the same, right hand circular polarization (RHCP) and left hand circular polarization (LHCP) are obtained, respectively. Then in Case 3 to 5, two stubs and two notches are embedded along orthogonal edges. Wider AR bandwidths are achieved and slot antennas with differently sized grounds are investigated. In Case 6, modified square slot antenna with reflecting conducting plate is proposed for 802.11 b/g (2400–2485 MHz) applications. All the simulated results are carried out by using Ansoft high-frequency structure simulator (HFSS 13) software.

Abstract—A high-gain and low-cost circularly polarized antenna array is proposed, which consists of four sequentially rotated circularly polarized square slot antennas (CPSSA). A novel feeding network is applied to the four-element array antenna, which results in increasing the axial ratio (AR) bandwidth. The measured impedance bandwidth for VSWR < 2 is around 3.48 GHz (3.75 GHz∼7.23 GHz) exhibiting a 2.8 GHz (3.8 GHz∼6.6 GHz) 3 dB axial-ratio bandwidth (ARBW) and 9.05 dBic peak gain. The simulated and measured results are in good agreement with each other to verify the design.

In this paper, a novel square slot antenna with CPW-fed is presented, which has not only good dual-band operation performance, but also simple structure and compact size. The proposed antenna consists of a special square slot resonator and a monopole radiator. The square slot etched on the ground, embedded with a tuning stub, can yield a new resonance mode. By adjusting the lengths of the square slot and tuning stub, the resonant frequency can be tuned independently and good impedance match can be obtained. All of these show that the antenna is suitable for both WiMAX and WLAN applications. The measured results are in good agreement with the simulated results. Details of the antenna design and experimental results analysis are demonstrated in the paper.

The CP cavity-backed square slot can be viewed as a circular polarizer loaded on a longitude waveguide-fed slot. The cavity plays a key role in impedance matching and polarization transformation. For the element, desired resonant conductance and circular polarization performance can be achieved by optimally adjusting the dimensions of the radiating slot, feeding slot, cavity and perturbations. The software ANSYS HFSS is used to conduct parametric study to obtain an optimal bandwidth for both return loss and AR performances. The operating frequency of 12.5 GHz is considered.

Figure 6 shows that the resonant point of the proposed antenna moves with the various gap (G). It is obvious that the resonant point moves up with the increasing gap resulting from the decrease of the capacitive couple between the F-shaped feeding structure and square slot. The value of the gap is set at 0.5 mm to cover the whole band of UHF RFID from 840 MHz to 960 MHz. The value of the gap makes slight impact on axial ratio as shown in Figure 6(b).

The antenna is initially analysed with a square slot, without having any stubs in the slot and additional L-slot at the top right corner of the ground plane. The CP bandwidth was only 33.84% even after optimizing different parameters of the antenna. In order to enhance the bandwidth, the electric field vector behaviour in the slot of the antenna at the centre frequency, 3 GHz, for one complete cycle is studied and is shown in Figure 2. 0 ◦ , 120 ◦ and 240 ◦ represents the polarization phase

A microstrip line-fed suspended square slot antenna with parasitic patch is presented. The proposed antenna is excited by a microstrip line feed placed at the bottom side of the substrate. The antenna geometry gets excitation via EM coupling. In this structure circular polarization (CP) is also obtained with suspended air gap and CP frequency can be switched between 4.5GHz to 5.5GHz. Thus, a 3 dB axial ratio bandwidth of about 4.32% is obtained. This structure exhibitsimpedance bandwidth, which is over 20.83%. The antenna was optimized with Ansoft’s HFSS software and was validated through a prototype. Measured results fairly agree with the simulated data.

FR4 is an inexpensive and easily available substrate material, which can be used to design efficient and cost effective microstrip patch antenna. This paper focuses on increasing the bandwidth of the microstrip patch antenna. Paper discusses about design of a elliptical patch antenna, having coaxial probe as a feed. To get the improved bandwidth, a rectangular slot has been digged along with a pin short, which changes the interaction of radiation. A huge increase in bandwidth is observed using the proposed design; almost 9 fold. All the simulation work is done using IE3D simulating software from Zeland has been used.

To achieve relatively wide impedance and AR bandwidths, the printed slot antennas with CP characteristic have been proposed in [5, 11], and the 3 dB axial ratio bandwidth of 18.85% and 12% are obtained, respectively. A proper rotation angle with respect to the center of square wide slot is selected to obtain the other resonant mode operating near one of the conventional wide-slot antennas [12]. The opposite slot in the ground makes the surface current distribution varies anticlockwise and generates the circular polarized radiation. However, the design of single-feed slot antenna with wide AR bandwidth and impedance bandwidth remains a challenging problem for antenna designers.

Modern telecommunication system require antenna with wider bandwidth and smaller dimensions. Various antennas for wide bandwidth operation have been studied for communication and radar system. The fractal antenna is preferred due to small size, light weight and easy installation. A fractal micro strip antenna is used for wideband application in this project provides a simple and efficient method for obtaining the compactness. An inverted square Koch based fractal antenna is designed for these applications. Its compactness and lighter weight is the major point for designing an antenna. This antenna is providing better bandwidth, return loss and gain.

The overall dimensions and also size of the metal square plate of the unit cell mostly influence the first resonance frequency, as mentioned before. However, increasing the overall dimensions of the AMC structure for decreasing the first resonance frequency is not preferred. One method for decreasing the first resonance frequency is adding slot in every side of the metal square plate in order to increase its length [17, 18]. First, adding one slot in every side of the square plate is tested and optimized for achieving the desirable result which is stated above. With the sizes of these obtained slots and due to the existence of a little distance between the slots specified in Fig. 7, probably the fabrication of this structure faces some challenges. Therefore, using two slots with smaller sizes is chosen, as illustrated in Fig. 8. In this optimization step, the air gap is increased to 5 mm. Also the size of the square slot in the center of the unit cell is decreased for enhancing the second resonance frequency. The final unit cell’s reflection phase is shown in Fig. 4. Further reviews show that the gain and radiation patterns of the antenna are more improved by enlarging the ground plane of the unit cells to the end of the microstrip feed line and with size of 64 × 100 mm 2 . The final proposed structure can be seen in Fig. 9 in different views.

frequency to create dual-band circular polarization, as illustrated in Figure 2. Both the two elements work as perturbation structures to distort the surface current and help to realize circular polarization. The CP operation for lower band is achieved by introducing two square slots placed around two opposite corners. The corner truncated square patch is the conventional technique to produce degenerate modes necessary for realizing broadband CP. Based on this theory, truncated corner at two opposite corners of the proposed antenna is tried to realize CP performance for upper band in this paper. The main slot is a corner truncated rectangular slot with a dimension of 28 mm × 30 mm, the truncation of W 1 = 9 mm and the square slot of

A compact microstrip-fed antenna with dual notched bands is proposed. First, a simple basic configuration is presented for Ultra Wide Band (UWB) applications and then the dual band notched structure is extended from the UWB one. The basic structure of the UWB antenna consists of a simple square radiating patch and a ground plane with a wide square slot on back of the substrate. A semi- circle shaped slot is cut from the ground plane to improve the antenna impedance matching. In the sequel, with the aim at filtering Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN), via-fed inverted T-shaped element and two rectangular stubs are embedded in the antenna structure. The presented antenna is printed on a 20 × 20 × 0.8 mm 3 FR4

The proposed antenna is designed with a hexadecagon-shape (16-sided polygon) on circular patch antenna. The ring slot and a square slot are loaded on the radiating patch to produce circular polarization. A diamond slot is considered at ground plane to reduce the return loss. Four rectangular slots at each corner are etched and added with a circular patch on ground plane to enhance the gain. HDCP antenna operates in dual bands with impedance bandwidths of 6.2% and 7.4%. The first operating frequency band 13.67 GHz (13.179–14.033 GHz) is operated at a space borne active sensor in EESS (Earth Exploration-Satellite Service), and the second band with operating frequency is 15.28 GHz (14.584–15.724 GHz) to work for mobile satellite service.

Abstract—A novel and simple dual-band dual-sense circularly polarized (CP) metal-strip antenna is proposed. The antenna fed by a coplanar waveguide (CPW) with the advantages of uniplanar geometry and easier fabrication consists of a square slot and two split-ring elements. By appropriately introducing dual split-ring elements, the proposed dual-band CP design can easily be achieved. The two resonant frequencies are controlled by the size of the two split-ring elements. The proposed antenna prototype is fabricated and measured. Experimental results show that good CP radiation performances are obtained at both resonant frequencies. The proposed antenna has an impedance bandwidth (|S 11 | ≤ −10 dB)

This square slot is fed by a 50- microstrip line with a simple tuning stub having a straight length of L mm, which is printed on the opposite side of the microwave substrate. For design simplicity, the width of the tuning stub is chosen to be the same as that of the 50 ohm microstrip line. Simulated results show that square slot antennas with various rotated angles need different tuning-stub length (L in Fig. 1) to be matched. The correct values can

Here, the effect of varying the slot dimension in a fixed size square patch is investigated. This phasing scheme preserves the distances between adjacent elements of the reflect array, and gives more freedom in selecting the separation between the array elements, or equivalently the unit cell size. Figure 1 shows the obtained phase responses for the family of slotted square patches. The considered square patch sizes are given by L = 6.0, 6.5, 7.0 and 7.5 mm. The phase variations are due to the variable size of the square slot inside the patch. It can be seen that a considerable reduction in the phase slope is obtained for the largest patch of 7.5 mm. However, this result is accompanied by reductions in the phase range. The extent of reductions in the slope and phase range depends on the outer size of the patch. Patch sizes that are not close to the resonant size offer smaller phase ranges and slopes. Note that for the chosen frequency of 10 GHz, the resonant size of the patch is 7.15 mm. As observed in Figure 1, the scheme with the slot

In this paper a serrated edged microstrip square patch antenna with an N-shaped slot has been designed for simultaneous use in Bluetooth (2.4-2.48 GHz) , WLAN (2.4 GHz) and WiMAX (2.3 GHz , 2.5 GHz) applications . The proposed antenna has an impedance bandwidth of 43.48%, VSWR of 1.87, radiation efficiency of 99.9%, antenna efficiency of 99.17%, gain of 3.41dB and directivity of 3.44dB, which are notable results.

Abstract—This paper presents a compact 2.45 GHz single feed directional circularly polarized (CP) microstrip antenna for radio frequency identification (RFID) applications. The proposed antenna comprises a dodecagonal microstrip patch embedded with an irregular polygonal slot, fabricated on an FR4 substrate. Two antennas, one with right-handed circular polarization (RHCP) and the other with left-handed circular polarization (LHCP), both resonating at a frequency of 2.45 GHz are presented. The measurement results show a 3 dB axial ratio bandwidth of 5.5%, a 10 dB impedance bandwidth of 5.7% for both the antennas, a peak gain of 4.82 dBi for RHCP antenna and 4.67 dBi for LHCP antenna. In addition, the antennas provide symmetrical patterns with 88 ◦ half-power beam width. The overall size of the antenna is 50 mm × 50 mm × 1.6 mm and offers an area reduction of 21.17%.