等离子天线介绍 [复制链接]

天线是所有射频通讯系统的重要组成部分.射频信号的收发从一般的广播到各种复杂的武器系统，其共同点都是使用一定尺寸的金属导体在所选用的频率上辐射或接收电磁波。由于金属天线一旦设计好，在结构上难以改变，在实际使用中受到环境、匹配等因数的影响其阻抗匹配等参数不容易达到比较理想的状态，即降低了金属天线的效率。
  等离子天线技术不采用传统的金属设计，而采用气体等离子体天线技术。这种崭新的天线设计技术在军事和民用上具有很大的发展潜力。相对于传统天线，等离子天线具有无可比拟的优点。
这种新型天线设计概念与传统的金属天线相比具有许多独特的优点，主要包括：①隐形性。当除去电离状态后，等离子体天线将不会产生后向散射雷达波，也不会吸收可降低电子对抗效能的高功率微波辐射。②适应于多种信号。等离子体天线具有可动态重构的特性，如带宽、频率、增益和指向性。③便于远程部署。等离子体天线可以比常规天线设计更轻、体积更小。④效率更高。等离子体天线很好地降低冲击激励效应，从而提高了短脉冲雷达的性能。这些独特的优点将使等离子体天线技术具有广阔的应用前景，如用于海军水面舰与潜艇雷达天线、隐形飞机雷达天线和弹道导弹防御雷达天线等。
什么是等离子?这是一种存在宇宙的地球上的物质形态，有液体和气体。英国物理学家威廉克鲁克斯爵士在1879年发现了一种物质的第四态，现在所谓的等离子体，等离子是迄今为止最常见的物质形式。在恒星和它们之间的微妙空间等离子体构成超过99％的可见宇宙，也许认为这是不可见的大部分。重要的是意大利航天局的技术，等离子和中性粒子带电，并表现出集体效应领域的导电组件。等离子体携带的电流，产生磁场。
等离子天线技术则采用电离气体作为一个天线单元真空管（或其形式）。这是从根本改变传统的天线设计，通常采用的固体金属元素的导电线。电离气体是一种有效的开展具有重要的一些优势。由于电离气体在传输或接收"响应”上比固体线天线有更多的优势。该设计允许极短脉冲，重要的是数字通信和雷达多种形式。该设计进一步提供了机会，构建一个天线，可以是小型化或紧凑型的,可以使用动态频率，在方向图，带宽，增益和波束上也可重新配置。等离子天线技术，使天线的效率高，低重量和体积小,优于传统的实心导线天线。
当带电气体或电离到等离子体状态变为导电性，使无线电频率（rf）信号发送或接收。我们用离子管作为一个封闭的天线进行分子气体。当气体不电离时，天线单元不再存在。
这样从根本改变传统的天线设计，通常采用的固体金属元素的导电线。我们相信我们的等离子体天线提供包括军事应用和商业应用的数字高隐身性能等优点。我们也相信我们的技术可以参加许多金属天线应用。我们最初的努力集中在军事市场。通用动力公司电船公司赞助2000年的占绝大部分的收入都超过16万美元的发展。
初步研究的结论是，等离子体天线的性能相当于一个在各方面铜线天线。等离子体天线可以用于任何传输和/或调制技术：连续波（cw），相位调制，脉冲，调幅，调频，啁啾，扩频或其他数字技术。和等离子体天线可以用在大范围高达20ghz的频率，并采用气体（如氖，氩，氦，氪，汞蒸气和泽农等）品种繁多。它作为一个接收天线也非常有实用的价值.
等离子天线具有明显的竞争优势，可以与大多数金属天线应用。比传统的金属元素的等离子体天线的优势是最明显的地方隐身和电子战是主要关注军事应用。其他重要的军事因素是重量，尺寸和重新配置的能力。潜在的军事应用包括：
是船用和潜艇的海底长波天线的替代品
无人机传感器的天线
海陆空“敌我识别器”天线
隐形飞机天线
宽带干扰设备扩频发射器（电子干扰）天线
相控阵天线
数字波束低轨道卫星及弹道导弹跟踪天线
太空天线等特别在长波领域和相控阵天线有最明显的优势，还可以节省庞大的费用开支。
在民用上等离子天线技术还可以用在测距术，宽带通讯，研了渗透的雷达、航海、天气雷达、风切变侦查和防撞、高速数据(例如互联网)通信扩展视谱通信和多孔的辐射防护上。
等离子天线的独特的特征

有时间再翻译

多少钱一副，lz有成品批发吗？

看了两遍，很吃力，以后慢慢认真看

不知道军事上有没有成功运用的例子，如果部队都搞不出来，ham也很难成功。

网上 摘录部分

电喷流是指在电离层水平方向流动的电流，它可以存在于任何纬度地带。但是，在两极附近电喷流要比低纬度地带强大得多。在极地的电喷流称为极光电喷流，它是产生极光的能源。

  要在地面上发射极低频电磁波是十分困难的。因为发射的天线必须与发射的低频电磁波的波长相匹配。如要发射30赫的电磁波，需要的天线长度为1000公里，显然是不可能的。但可以利用强大的极光电喷流来做虚拟天线。极光作为一种活动的非线性介质，其主要能量集中于2.8～10兆赫，这和haarp的工作频率是一致的。haarp用载波（其频率范围是2.8～10兆赫）将其要发射的频率（低频或高频）进行调制，然后发射至臭氧层。如果haarp的频率能引起极光电喷流谐振，那么就可以把极光电喷流变成一个虚拟天线。使之辐射出具有极强能量的电磁波，其高频可到几百万赫，低频可低至0～1000赫......

等离子天线技术采用电离气体作为一个天线单元。从根本改变传统的天线设计，gp天线通常采用的固体金属导电线。而电离气体是一种有效的开展具有重要的一些优势要素。由于电离气体的传输或接收，该设计允许极短脉冲，重要的是数字通信和雷达多种形式。该设计进一步提供了机会，构建一个 一个根本区别天线的特点是，等离子气体电离过程可以操纵性。 当去离子，气体具有无限性和不与射频辐射。当去离子气体散射雷达天线不会波（提供隐形），不会吸收高功率微波辐射（减少影响的对策电子战）。
第二个基本特点是，在发出一个脉冲等离子体天线可以去离子，消除了振铃与传统的金属元素相关联。响应和脉冲传输相关的金属天线噪声的严重限制功能，可以在较短的高频率。 在这些应用中，金属天线往往伴随着复杂的计算机信号处理。 通过减少振荡和噪音，我们相信我们的等离子天线可提供更高的精确度，减少电脑信号处理的需要。 这些优势是在高速数字通信的重要应用尖端雷达和用于脉冲高。
日期计算结果的发展，等离子天线技术有以下附加属性：

· 无振铃提供了改进的天线信噪比，降低多径信号失真。
·减少雷达散射截面提供隐形由于非金属元素。
. 离子密度¨的变化可能导致瞬间变化的带宽在宽动态范围。
·气体被电离后，等离子体天线几乎没有噪声。
操作·虽然在一个水平电离等离子体天线具有低可解耦从毗邻的高频发射器。
· 一个可以进行循环扫描电子零件，没有移动天线结构在更高的速度比传统的机械。
·它已被数学说明，通过选择和改变的气体离子密度电光圈）的等离子体天线（或明显的足迹，可达到标准执行，具有金属的大小对应具有较大的体力。
·我们的等离子体天线可以发送和接收来自同一光圈提供的频率相距甚远。
. 等离子共振，阻抗和电荷密度都是动态可重构。 . 电离气体天线元素可以建造和方向性配置到一个数组，它是动态配置频率，波束宽度，功率，增益，极化-对飞。
··一个单一的动态天线结构可以利用时间多，使许多rf子系统可以共享一个天线资源减少的数量和结构的大小的天线。
赞助相关工作

. 到目前为止，等离子天线技术进行了研究和技术公司的特点是揭示与意大利航天局天线应用几个连接有利属性研究。 这项工作进行了赞助合同的一部分，通过两个合同。圣地亚哥授予合同n66001 - 97 -的m - 1153 1997年5月1日。 该方案的主要目标是确定天线接收的噪声水平有关，与使用的气体等离子导体的传输和。
实验室和现场试验进行了测量。 第二份合同n00014 - 98 - c型0045是6个月获sbir计划合同11月15日，1997年。在这种努力的主要目标是描述gp天线的噪声排放电导率，电离故障，上限频率的限制，激发和弛豫时间，点火机制，温度及热和比较这些结果与参考折叠单极铜线。 等离子体天线的辐射图测量相比非常好，铜导线天线。
意大利航天局技术公司正在与通用动力部合约电船和发展结合等离子体物理实验室在美国田纳西州大学，一个正在充气等离子体天线。 这种天线的设计工作在2.4 ghz和潜艇将安装在桅杆上的攻击。 此外原型等离子和等离子反射波导的设计和证明通用动力。
下面的讨论说明了为什么有军方和政府支持等离子天线的概念。
气体等离子体天线进行电子电流像金属，因此可以被制作成天线的优点，但具有鲜明。
下面的科技概念是很重要的等离子天线：

1. 1. 更高的功率-提高功率可以实现在等离子体天线比欧姆损耗低，因为相应的金属天线。 等离子体聚变反应堆有动力实验普林斯顿大学等离子体中的金属比范围更广泛的能力明显的权力从低功率等离子在极高的荧光灯泡。 在此范围内，一个高功率等离子体天线仍是低功率等离子体。 由于等离子体不融化，等离子体天线可以提供热量和防火性能。 实现更高的功率和天线方向性等离子可以提高目标识别和跟踪弹道导弹，在x波段和s。
2. 2. 增强带宽-以激光器使用电极或等离子体密度可以控制的。. 时间和空间的理论密度计算中对血浆受控变化表明，等离子体天线的更大的带宽可以达到几何比同相应的金属天线。 此增强的带宽可以提高。
3. 3. 电磁干扰/电磁兼容-等离子天线是透明的低密度传入的电磁信号或关闭模式。 这消除或减少电磁干扰/电磁兼容从而产生隐形。几个等离子体天线可以有自己的电子密度的调整，使它们可在靠近天线可以操作和一个别人看不见的。 在这个物理安排相互旁瓣和后瓣杂波高度降低，因此干扰和杂波减少。
4. 4. 更高的效率，增益-辐射天线的效率较高，在等离子体中，由于等离子体的窗口中的低欧姆损失。 驻波效率更高，因为天线匹配相结合的饲料可以通过调整等离子体密度和可重新配置过程中保持。 估计表明天线效率20db的改善研究。
5. 5. 重构和mutifunctionality -等离子天线可以重新配置天线金属安排飞比任何变化更为多样化的控制时间的等离子体的窗口和密度的空间。 这减少了天线数量减少船上所需元素的大小和重量。. 一种选择是构造控制等离子体密度等离子体天线周围毛毯从而创造（高等离子体的中的分子密度区）窗口（低密度节的密度）或接待和主瓣关闭传输窗口。 .等离子体作用增强方向性和增益天线单元在一个单一的等离子体，这样将有一个数组天线阵列较少比相应的金属元素。 在关闭等离子体后等离子体和旁瓣消除它们存在，并降低干扰和杂波。 这低于40db的旁瓣降低增强了方向性和歧视。此外，通过改变等离子体的密度，单一天线可以工作在一个带宽（如通信），而抑制另一种带宽（如雷达）。
6. 6. 噪音低-等离子天线具有较低的金属天线之间的载流子碰撞率比和计算表明，这意味着更少的噪音。
7. 7 理想反射-当等离子体密度较高的血浆成为无损耗理想反射。 . 因此，存在反射面天线的可能性轻量级等离子体范围广。

what is plasma?

on earth we live upon an island of "ordinary" matter. the different states of matter generally found on earth are solid, liquid, and gas. sir william crookes, an english physicist identified a fourth state of matter, now called plasma, in 1879. plasma is by far the most common form of matter. plasma in the stars and in the tenuous space between them makes up over 99% of the visible universe and perhaps most of that which is not visible. important to asi's technology, plasmas are conductive assemblies of charged and neutral particles and fields that exhibit collective effects. plasmas carry electrical currents and generate magnetic fields.

plasma antenna technology

since the discovery of radio frequency ("rf") transmission, antenna design has been an integral part of virtually every communication and radar application. technology has advanced to provide unique antenna designs for applications ranging from general broadcast of radio frequency signals for public use to complex weapon systems. in its most common form, an antenna represents a conducting metal surface that is sized to emit radiation at one or more selected frequencies. antennas must be efficient so the maximum amount of signal strength is expended in the propogated wave and not wasted in antenna reflection.

plasma antenna technology employs ionized gas enclosed in a tube (or other enclosure) as the conducting element of an antenna. this is a fundamental change from traditional antenna design that generally employs solid metal wires as the conducting element. ionized gas is an efficient conducting element with a number of important advantages. since the gas is ionized only for the time of transmission or reception, "ringing" and associated effects of solid wire antenna design are eliminated. the design allows for extremely short pulses, important to many forms of digital communication and radars. the design further provides the opportunity to construct an antenna that can be compact and dynamically reconfigured for frequency, direction, bandwidth, gain and beamwidth. plasma antenna technology will enable antennas to be designed that are efficient, low in weight and smaller in size than traditional solid wire antennas.

when gas is electrically charged, or ionized to a plasma state it becomes conductive, allowing radio frequency (rf) signals to be transmitted or received. we employ ionized gas enclosed in a tube as the conducting element of an antenna. when the gas is not ionized, the antenna element ceases to exist. this is a fundamental change from traditional antenna design that generally employs solid metal wires as the conducting element. we believe our plasma antenna offers numerous advantages including stealth for military applications and higher digital performance in commercial applications. we also believe our technology can compete in many metal antenna applications. our initial efforts have focused on military markets. general dynamics' electric boat corporation sponsored over $160,000 of development in 2000 accounting for substantially all of our revenues.

initial studies have concluded that a plasma antenna's performance is equal to a copper wire antenna in every respect. plasma antennas can be used for any transmission and/or modulation technique: continuous wave (cw), phase modulation, impulse, am, fm, chirp, spread spectrum or other digital techniques. and the plasma antenna can be used over a large frequency range up to 20ghz and employ a wide variety of gases (for example neon, argon, helium, krypton, mercury vapor and zenon). the same is true as to its value as a receive antenna.

market applications of plasma technology

plasma antennas offer distinct advantages and can compete with most metal antenna applications. the plasma antenna's advantages over conventional metal elements are most obvious in military applications where stealth and electronic warfare are primary concerns. other important military factors are weight, size and the ability to reconfigure. potential military applications include:

· shipboard/submarine antenna replacements.
· unmanned air vehicle sensor antennas.
· iff ("identification friend or foe") land-based vehicle antennas.
· stealth aircraft antenna replacements.
· broad band jamming equipment including for spread-spectrum emitters.
· ecm (electronic counter-measure) antennas.
· phased array element replacements.
· emi/eci mitigation
· detection and tracking of ballistic missiles
· side and backlobe reduction

military antenna installations can be quite sophisticated and just the antenna portion of a communications or radar installation on a ship or submarine can cost in the millions of dollars.

plasma antenna technology has commercial applications in telemetry, broad-band communications, ground penetrating radar, navigation, weather radar, wind shear detection and collision avoidance, high-speed data (for example internet) communication spread spectrum communication, and cellular radiation protection.

unique characteristics of a plasma antenna

one fundamental distinguishing feature of a plasma antenna is that the gas ionizing process can manipulate resistance. when deionized, the gas has infinite resistance and does not interact with rf radiation. when deionized the gas antenna will not backscatter radar waves (providing stealth) and will not absorb high-power microwave radiation (reducing the effect of electronic warfare countermeasures).

a second fundamental distinguishing feature is that after sending a pulse the plasma antenna can be deionized, eliminating the ringing associated with traditional metal elements. ringing and the associated noise of a metal antenna can severely limit capabilities in high frequency short pulse transmissions. in these applications, metal antennas are often accompanied by sophisticated computer signal processing. by reducing ringing and noise, we believe our plasma antenna provides increased accuracy and reduces computer signal processing requirements. these advantages are important in cutting edge applications for impulse radar and high-speed digital communications.

based on the results of development to date, plasma antenna technology has the following additional attributes:

· no antenna ringing provides an improved signal to noise ratio and reduces multipath signal distortion.
· reduced radar cross section provides stealth due to the non-metallic elements.
· changes in the ion density can result in instantaneous changes in bandwidth over wide dynamic ranges.
· after the gas is ionized, the plasma antenna has virtually no noise floor.
· while in operation, a plasma antenna with a low ionization level can be decoupled from an adjacent high-frequency transmitter.
· a circular scan can be performed electronically with no moving parts at a higher speed than traditional mechanical antenna structures.
· it has been mathematically illustrated that by selecting the gases and changing ion density that the electrical aperture (or apparent footprint) of a plasma antenna can be made to perform on par with a metal counterpart having a larger physical size.
· our plasma antenna can transmit and receive from the same aperture provided the frequencies are widely separated.
· plasma resonance, impedance and electron charge density are all dynamically reconfigurable. ionized gas antenna elements can be constructed and configured into an array that is dynamically reconfigurable for frequency, beamwidth, power, gain, polarization and directionality - on the fly.
· a single dynamic antenna structure can use time multiplexing so that many rf subsystems can share one antenna resource reducing the number and size of antenna structures.
sponsored work

to date, plasma antenna technology has been studied and characterized by asi technology corporation revealing several favorable attributes in connection with antenna applications. the work was carried out in part through two onr sponsored contracts. nccosc rdte division, san diego, awarded contract n66001-97-m-1153 1 may 1997. the major objective of the program was to determine the noise levels associated with the use of gas plasma as a conductor for a transmitting and receiving antenna. both laboratory and field-test measurements were conducted. the second contract n00014-98-c-0045 was a 6-month sbir awarded by onr on november 15, 1997. the major objective of this effort was to characterize the gp antenna for conductivity, ionization breakdowns, upper frequency limits, excitation and relaxation times, ignition mechanisms, temperatures and thermionic noise emissions and compare these results to a reference folded copper wire monopole. the measured radiation patterns of the plasma antenna compared very well with copper wire antennas.

asi technology corporation is under contract with general dynamics electric boat division and in conjunction with the plasma physics laboratory at the university of tennessee, an inflatable plasma antenna is being developed. this antenna is designed to operate at 2.4 ghz and would be mounted on the mast of an attack submarine. in addition a prototype plasma waveguide and plasma reflector has been designed and demonstrated to general dynamics.

the following discussion illustrates why there is military and government support for plasma antenna concepts. the gas plasma antenna conducts electron current like a metal and hence can be made into an antenna but with distinct advantages. the following technological concepts are important to plasma antennas:

1. higher power - increased power can be achieved in the plasma antenna than in the corresponding metal antenna because of lower ohmic losses. plasmas have a much wider range of power capability than metals as evident from low powered plasma in fluorescent bulbs to extremely high-powered plasmas in the princeton university experimental fusion reactors. in this range, a high-powered plasma antenna is still low powered plasma. since plasmas do not melt, the plasma antennas can provide heat and fire resistance. the higher achievable power and directivity of the plasma antenna can enhance target discrimination and track ballistic missiles at the s and x band.

2. enhanced bandwidth - by the use of electrodes or lasers the plasma density can be controlled. the theoretical calculations on the controlled variation of plasma density in space and time suggest that greater bandwidth of the plasma antenna can be achieved than the corresponding metal antenna of the same geometry. this enhanced bandwidth can improve discrimination.

3. emi/eci - the plasma antenna is transparent to incoming electromagnetic signals in the low density or turned off mode. this eliminates or diminishes emi/eci thereby producing stealth. several plasma antennas can have their electron densities adjusted so that they can operate in close proximity and one antenna can operate invisible to others. in this physical arrangement mutual side lobe and back lobe clutter is highly reduced and hence jamming and clutter is reduced.

4. higher efficiency and gain - radiation efficiency in the plasma antenna is higher due to lower ohmic losses in the plasma. standing wave efficiency is higher because phase conjugate matching with the antenna feeds can be achieved by adjusting the plasma density and can be maintained during reconfiguration. estimates indicate a 20db improvement in antenna efficiency.

5. reconfiguration and mutifunctionality - the plasma antenna can be reconfigured on the fly by controlled variation of the plasma density in space and time with far more versatility than any arrangement of metal antennas. this reduces the number of required elements reducing size and weight of shipboard antennas. one option is to construct controlled density plasma blankets around plasma antennas thereby creating windows (low-density sections of the blanket) for main lobe transmission or reception and closing windows (high-density regions in the plasma blanket). the plasma windowing effect enhances directivity and gain in a single plasma antenna element so that an array will have less elements than a corresponding metal antenna array. closing plasma windows where back lobes and side lobes exist eliminates them and reduces jamming and clutter. this sidelobe reduction below 40db enhances directivity and discrimination. in addition, by changing plasma densities, a single antenna can operate at one bandwidth (e.g. communication) while suppressing another bandwidth (e.g. radar).

6. lower noise - the plasma antenna has a lower collision rate among its charge carriers than a metal antenna and calculations show that this means less noise.

7. perfect reflector - when the plasma density is high the plasma becomes a loss-less perfect reflector. hence there exist the possibilities of a wide range of lightweight plasma reflector antennas.

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