查询词典 in-line antenna

This article first antenna, microstrip theory, the circular polarization technology, the theoretical discussion, in this based on the microstrip antenna of circular polarization method - corner square microstrip antenna, and has done a design simulation , and then do the design and further research to improve and eventually get a resonant frequency (S11 reflection coefficient corresponding to the minimum frequency) for the 1.5GHz and 1.43GHz, the frequency of circular polarization for the 1.46GHz, S11 is less than -10dB relative bandwidth, the VSWR is less than 2 is about 8.8% relative bandwidth, axial ratio less than 3dB relative bandwidth of about 2.2% of the right circular polarization microstrip antenna design case, which proved very good the circular polarization microstrip antenna theory, also fully confirmed by a square corner design is a practical program, and select the appropriate regulation of sticks is indeed able to improve the performance of the antenna.

本文先对天线、微带理论、圆极化技术等进行了理论论述，在此基础上，提出圆极化微带天线的实现方法——切角方形微带天线，并对此做了设计仿真，后又对这一设计方案做了改进及进一步研究，最终得到一个谐振频率（反射系数S11 的最小值所对应的频率）为1.5GHz和1.43GHz，圆极化频率为1.46GHz，S11 小于-10dB 的相对带宽、驻波比小于2 的相对带宽约为8.8%，轴比小于3dB 的相对带宽约为2.2%的右旋圆极化微带天线的设计案例，从而很好的印证了圆极化微带天线理论，也充分证实了切角方形是一种切实可行的设计方案，而选取合适的调节枝则确能提高天线的性能。

At present, the wireless devices in general to bring the whole antenna, omni-directional radio antenna to the antenna axis, was "donut"-shaped radiation field; directional antenna is highly directional, in the small angle of radiation is totally outside the scope of signals ; the use of removable external antenna equipment can gain antenna, the antenna can not increase in the case of radiated power to increase communication distance.

目前的无线设备一般自带全向天线，全向天线电波以天线为轴，呈"面包圈"状向外辐射；定向天线具有极强的方向性，在小角度的辐射范围外是完全没有信号的；使用可拆卸天线的设备可以外接增益天线，可以在不增加天线辐射功率的情况下增加通讯距离。

The va lues of these multipath parameters can be used to make a criterion suitable for environment classification in software antenna systems , and the eigenvalue distr ibution can be used to identify the type of various environments .

因此根据多径参数的大小可以确定适合软件天线环境分类的分类标准，并且根据矩阵特征值的分布特点可以识别不同的环境类别

These antennas can cover GSM900/DCS/PCS/UMTS operation. In the chapter 2, the antenna is designed based on the concept of monopole antenna. Furthermore, the antenna structure have two radiant paths and coupled each other at tail end to do impedance matching. In addition, to raise distance between radiation plane and ground will avoid capacitative effect effectually. In the chapter 3, the antenna is designed based on the concept of planar inverted-F antenna. Furthermore, that the antenna structure have two radiant paths and coupled each other at tail end to do impedance matching is similar to chapter 2. But there is a difference in them. We can choose the short position to change input impedance at this structure. In the chapter 4, the antenna is designed based on the concept of planar inverted-F antenna which takes coupled-fed. It will produce the first mode and high-order mode near the frequency, 900MHz. The feature of this type is to reduce the volume effectually. This antenna can not only cover GSM900/DCS/PCS/UMTS operation but maintain good radiation efficiency. Finally, we will compare three antennas, and develop procedure with industrial view, and propose the prospect of the GSM/GPRS antenna in PND, as a conclusion.

在第二章中，我们使用单极天线设计概念，使用双路径架构并於末端耦合来对天线阻抗做匹配，产生涵盖GSM900/DCS/PCS/UMTS四频操作频带，并提高与接地面的辐射高度，以避免电容效应，使天线具有良好的辐射特性；在第三章中，使用倒F形天线设计概念，使用双路径架构於末端耦合，并於辐射臂上采取适当接地点电感效应作输入阻抗匹配，达成涵盖GSM900/DCS/PCS/UMTS系统的四个操作频带；在第四章中，采用倒F形架构并使用耦合馈入方式，使得长辐射金属臂在低频900 MHz附近产生共振，产生低频基频模态及高阶模态，以达成宽频及频宽涵盖GSM900/DCS/PCS/UMTS频带操作，并有效缩减使用体积；最后，分别比较此三种架构的优缺点，再加以业界角度来思考，研发产品天线的流程及思考方向，以及天线应用於可携式导航装置中未来的展望作为本论文的总结。

In modern specification of handset, there is one about SAR. However, current mobile phone antenna is dipole antenna with omni-directional radiation pattern in azimuth plane. So much better performance of antenna means higher SAR value. Therefore, in order to improve SAR performance, designer may be forced to detune antenna or use resistor. The two methods will reduce efficiency of antenna.

在移动电话的技术规范中往往有SAR值的要求，这给手机天线的设计带来了严峻的挑战，因为现代的手机天线基本上是在水平面具有全向辐射特点的偶极子天线，因此天线的性能越好往往SAR值越高，所以有时为了降低SAR值甚至故意劣化天线的性能。

The antenna system includes a mechanism for electrically connecting the displaceable antenna to internal RF circuitry of the portable WCD when the displaceable antenna is in an extended position and for electrically isolating the displaceable antenna from the internal RF circuit when the displaceable antenna is in a retracted position within the casing.

该天线系统包括一个机构，用来在可移动天线处于拉伸位置时把可移动天线电连接至便携式WCD的内部RF电路，并在可移动天线处于外壳内的收缩位置时把可移动天线和便携式WCD的内部RF电路电隔离。

In receiving antenna, when a cone-channel condenser is located at the exit pupil of a Keplerian telescope, proper field of view is obtained without tracking system at the receive end, because the receiving optical power of APD will keep stable to a great extent when the incident beam deflects.

发射天线包括准直镜和扩束镜两部分，出射光束发散角压缩到1mrad；接收天线采用非成像光学设计，将接收光锥置于望远系统的出瞳位置，保证了大视场光束的准确接收，从而提高了系统抗干扰能力。

To prevent the interference in the antenna all-round rotation plane the nose landing gear legs are retracted rearward into the cowlings flight-wise and the main legs are retracted upward.

为防止在天线干扰全面旋转飞机前起落架腿缩回到整流罩飞行明智的，主要是收回腿向后向上。

To overcome the drawbacks in the weight and cost of the antenna with the corrugated soft surface, a new patch antenna with patch rings is designed. Its weight is about 1/4 less than the antenna with the corrugated soft surface and it is inexpensive. Good experimental results are obtained. The radiation pattern of the antenna is more rotationally symmetric, and a more reduction on the sidelobe levels of the antenna is achieved as compared to the antenna with the corrugated soft surface. In conclusion, in the present thesis both theoretical and experimental research works have been carried out intensively on patch antennas based on photonic-bandgap structures.

为了克服皱褶软表面天线份量重，加工费用贵等缺点，我们对空气介质的皱褶圆环结构软表面天线进行了改进，将周期分布的皱褶圆环平面化，并保持结构的软表面特性，设计出了一种新的平面圆环结构的软表面天线并进行了实验研究，加工的平面圆环结构天线比皱褶圆环结构天线重量减轻了约1/4，加工费用大大降低，所取得的实验结果显示，该平面圆环结构软表面天线的方向图的轴对称性得到了改善，在俯仰角从0°～-90°的范围内天线H面的波束与E面重合，与皱褶圆环结构相比，天线的旁瓣和背瓣受到了更大的抑制，E面方向图上+120°方向的旁瓣被明显削弱。

The research on reconfigurable antennas is a hot point in the antenna field.

可重构天线是当前天线领域的研究热点。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。