若同样的使用频率，同样的加感线圈，中部加感与底部加感在振子长度总长度上是否有区别？同样的天线加感位置不同对效率有什么影响？中部加感的位置是可以计算出来最好的点还是任选？都有中部，底部加感了有没有顶部加感？萌新在线求大佬解答

LK0943 [Q]水平偶极天线振子的最短理想长度是工作频率的半波长。因条件限制而必须缩短振子时，不得不在天线的某个地方串入额外的电感将振子的自然谐振频率补偿到工作频率，但天线的效率比半波长天线有所降低。图为常用的方案，如果振子（红色部分）总长度相等，各方案的名称以及按发射效率由高到低的排序为： C-顶部加感,B-中间加感,A-底部加感 LK0944 [Q]垂直GP天线振子的最短理想长度是工作频率的1/4波长。因条件限制而必须缩短振子时，不得不在天线的某个地方串入额外的电感将振子的自然谐振频率补偿到工作频率，但天线的效率比1/4波长天线有所降低。图为常用的方案，如果振子（红色部分）总长度相等，各方案的名称以及按发射效率由高到低的排序为： C-顶部加感, B-中间加感, A-底部加感 LK0935 [Q]在因空间限制、HF偶极天线达不到自然谐振所需长度而必须缩短时，可以在天线电路的某一点串入一个线圈，或者将整个振子做成一个线圈，加以补偿，构成“加感天线”。在充分优化设计的条件下，它们与全尺寸半波长偶极天线相比较的结果是：可以和全尺寸天线一样满足谐振和阻抗匹配条件，但辐射效率肯定不如全尺寸天线我能找到题库里面三个题供你参考

加感位置不同，振子长度有区别，趋势是加同样的感，越接近天线馈电根部，振子所需长度越短。这一点随便用一个天线仿真软件就能验证了

这个问题还挺好的，给你点赞。

I have a few questions regarding adding capacitance in the center and at the bottom of an antenna.

BI4PMQ

If the same usage frequency and coil configuration are used, does the difference in adding capacitance at the center versus at the bottom affect the total length of the resonant circuit?
How do different antenna and feed positions affect efficiency?
Is it possible to calculate the optimal location for adding a sensor in the center, or should I simply choose one at random?
Do they all have a middle part? Does the bottom also have a "plus" sign? Is there a top part with a "plus" sign as well?
New player seeking help from experienced users.

BH7HQT

从振子总长度角度来说没区别，但是似乎加感位置对辐射效率有影响。个人能力有限，可进行进一步仿真。

参考：https://www.hellocq.net/forum/read.php?tid=259168

以下搬运自Kimi AI：

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加感天线在不同部位加感的区别主要体现在以下几个方面：

• 集中电感加载：这种加载方式是在天线的适当部位，如中部某点插入一个电感线圈，这个电感线圈的感抗可以抵消这点以上天线振子在该点所呈现的全部或部分容抗，从而加大了加感点以下的天线电流，即提高了天线的有效高度。这种在天线中部插入线圈的方法常见于车载台天线（吸盘天线）。

• 分布电感加载法：均匀地在天线上加入电感，其实例就是移动通信中广为采用的螺旋鞭天线。螺旋鞭天线是用弹簧钢丝制成螺旋鞭天线，再在其外表涂覆一层介质，如橡胶等，介质起的主要作用是固定线圈之间相对位置，这就形成了分布加载天线加载天感分布于螺旋鞭天线螺旋线圈的始终。

• 底部加载：从机械的角度看，底部加载最为理想，但是这种加载方式的辐射电阻很低而且由于大多数能量是从加载线圈辐射出来，因此效率比较低。

• 中部加载：中部加载的辐射电阻会增加，但在这种情况下要产生谐振就得有更大的电感，加载的位置越向上，所需的电感就越大。从各个因素来考虑，中部加载的天线是最好的。

• 顶部加载：顶部加载的天线较少见，这是因为沉重的电感线圈会使整个结构变得笨重，天线的机械强度难以得到保证。

• 辐射效率：如果电感加在天线电流最大的部分（底端），对天线辐射影响最大，阴影部分面积最小，辐射效率越高。如果电感加在天线电流最小的地方（顶端），对天线辐射影响最小。

• 天线的谐振：对于短于1/4波长的天线，呈容性，想要谐振就要加感抵消电抗成分。电感里面虽有电流流过，但产生的磁场是沿线圈轴向，产生的向外有效辐射少。

总结来说，加感天线在不同部位加感会有不同的效果，包括影响天线的有效高度、辐射效率、谐振特性以及机械稳定性。中部加感通常被认为是效率较高的一种方式，但具体选择哪种加感方式还需要根据实际应用场景和需求来决定。
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Bi4KKF

LK0943
[Q] The ideal shortest length for a horizontal dipole antenna resonator is half the wavelength of the operating frequency. When the resonator must be shortened due to constraints, an additional inductor must be inserted somewhere on the antenna to compensate for the natural resonant frequency of the resonator and bring it to the operating frequency, but this reduces the efficiency of the antenna compared to a half-wavelength antenna. The diagram shows a common solution. If the total length of the resonator (red part) is equal in each scheme, the names of the schemes and their ranking from highest to lowest based on transmission efficiency are as follows:
C - Top with emphasis, B - Middle with emphasis, A - Bottom with emphasis

LK0944
[Q] The shortest ideal length for a vertical GP antenna resonator is 1/4 wavelength of the operating frequency. When the resonator must be shortened due to constraints, an additional inductor must be inserted somewhere on the antenna to compensate for the natural resonant frequency of the resonator to match the operating frequency, but this reduces the efficiency of the antenna compared to a 1/4 wavelength antenna. The diagram shows a common solution. If the total length of the resonator (red part) is equal, the names and ranking of the schemes according to transmission efficiency from highest to lowest are:
C - Top with emphasis, B - Middle with emphasis, A - Bottom with emphasis

LK0935
[Q] When space limitations or the need to shorten an HF dipole antenna to achieve natural resonance, a coil can be inserted at some point in the antenna circuit, or the entire oscillator can be made into a coil, to compensate, forming a "tuned antenna." Under optimal design conditions, compared to full-size half-wave dipoles:
It can meet resonance and impedance matching conditions similar to full-size antennas, but its radiation efficiency will definitely be lower than that of full-size antennas.

I was able to find three questions from the question bank that you can refer to.

BH7JUO

The position of the added capacitance differs, and the length of the inductor also varies. The general trend is that the shorter the added capacitance, the closer it is to the feed point of the antenna, the shorter the required length of the inductor. This can be easily verified using any antenna simulation software.

BG7NOD

This is a really good question, I like it!

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