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The invention relates to a new double - band slot ultra - wideband slot
The antenna
Yao zhenfang, wang xiaoxia, zhou shiguo, li liqun. Sun, b. h. sun and q. Z. Liu
State key laboratory of antenna and microwave technology, xidian university
windsl@163.com bhsun@mail.xidian.edu.cn qzhliu@xidian.edu.cn
A novel ultra wideband (uwb) design of a single-layer coplanar waveguide fed monopole antenna with dual bandgap is presented. The double band gap characteristics are realized by adding a tuning nipple to the radial ring and etching two l-shaped slots in the ground plane of the CPW. The design of antenna is introduced in detail, and the measurement results of VSWR, radiation mode and gain are given. The experimental results show that the antenna has 2.5-12ghz uwb when the VSWR is less than 2, except for two resistance bands of 3.3-4.2ghz and 5.2-6.0ghz.
My introduction.
In recent years, uwb system has become a research hotspot in the field of wireless communication due to its advantages of small size, fast data rate of transmitter and low power consumption. Several antenna structures are studied for uwb applications ([2]-[5]). However, due to the distribution of the wide frequency range (3.1 to 10.6 GHz) in uwb system by the federal communications commission [1], a uwb antenna is easy to interference by receiving several adjacent rf system of narrow-band signals, such as the IEEE 802.11 WLAN system operation 5.15-5.825 GHz, IEEE 802.16 to 3.3-3.6 GHz Wimax system operation and c band (3.7 to 4.2 GHz) satellite communications system. Therefore, it is necessary to design an uwb antenna with bandgap characteristics to avoid potential interference. Some uwb antennas with band suppression function have been reported in the literature ([6]-[9]), but each structure in these antennas can only produce a notch band. Some uwb monopole antennas with double choke bands are also reported. The double choke band is formed by inserting two or three u-shaped slots into a monopole radiator. However, they require a vertical ground, resulting in increased antenna size and difficulties integrating with monolithic microwave integrated circuits. In recent years, some new double-band gap antennas ([12], [13]) have been designed. But the geometry of the antenna
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978-1-4244-2193-0/08 / copy; 2008 IEEE 25.00 dollars
Relatively complex. In addition, the two rejected bands cannot be tuned separately.
A novel coplanar waveguide fed monopole antenna for ultra wideband applications is proposed. Two l-shaped slots on the CPW ground were used to realize the stopband of 3.3 ~ 4.2 GHz. To obtain another choke band (5.2 to 6ghz) to suppress the bandwidth of the wlan, attach a tuning stub to the radiating ring. By adjusting the position and length of the relevant slots, the grooving band can be controlled without interfering with other stopbands. The design of antenna is introduced in detail. The experimental results and discussion are given.
Ii. ANTENNADESIGN
The antenna is printed on the substrate RT6010 with a thickness of 1.6mm and a relative dielectric constant of 10.2. Its geometric parameters are shown in figure 1, and the antenna prototype is shown in figure 2. The width and length of the rectangular substrate are 30mm and 25mm respectively. 50 m-cpw feed line center width w = 2mm, clearance g = 0.4mm. Print a circular patch with a radius of R1=7mm on the front surface of the substrate. To expand the impedance bandwidth, insert a groove with a radius of R2=4.2mm on the main wafer. Then a tuning nipple is attached to the radiating ring to realize the bandgap characteristics. Finally, in order to obtain another choke band, an l-shaped slot is etched on each side of the ground plane to make the antenna symmetric along the center Y-axis. The optimal values of antenna parameters are shown in table 1.
Table 1 optimal value of antenna parameters
Figure 1 suggests the geometry of the antenna.
Figure 2 photos of the proposed antenna.
Iii. BAND-NOTCH function study
Ansoft high frequency structure simulator (HFSS) was used to optimize the antenna. Figure 3 shows the simulated VSWR of the antenna with different tuning stub length h values under the condition that other dimensions remain unchanged. Thus, the length of the tuning stub is the key parameter that determines the center frequency of the 5.2-6 GHz stop band. The extended stub (h) resonates at the notch frequency because the current is concentrated at the lower edge of the stub, thus substantially increasing the impedance at the antenna feed point, leading to rejection at the resonant frequency (notch frequency). In order to further illustrate the influence of inverted l-slot on another notch frequency band, figure 4 shows the simulated VSWR of the antenna at different l-slot positions. It is found that the value of m determines the frequency range of 3-4.2 GHz notch frequency band. Also note that by adjusting the length of h and the position of the associated slot m
Figure 3 simulation diagram of VSWR with different tuning segment lengths.
Figure 4 VSWR simulation diagram of different l-shaped slot positions.
IV. EXPERIMENTALRESULTS ANDDISCUSSION
The VSWR of the antenna was measured by WILTRON37269A vector analyzer. Figure 5 shows the simulation and measured results of VSWR with frequency of the designed antenna. It can be seen from the measured results that the designed antenna has two stopbands of 3.2-4.2ghz and 5.3-6ghz, and maintains the broadband performance of 2.5-12ghz when VSWRlt;2, covering the entire UWB frequency band.
The far-field radiation characteristics of the antenna are studied. Figure 6 shows the measured radiation modes of
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