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bh9feh 2021-12-03 18:00

请教：垂直天线匹配段的作用？

看到一个短波垂直天线在加感段的下面，有个匹配段，它的作用是什么？
为什么有的gp天线没有匹配段？

bi4sqm 2021-12-03 18:43
盲猜2个作用，1是用作地网，调整阻抗，2是形成电容，和加感部分一起作用，调整感抗。

yangjiang 2021-12-03 18:45
我觉得是跟电感线圈形成一个自耦变压器做阻抗匹配吧？

bh9feh 2021-12-03 19:14
图上说是调整驻波用的，问题是有的gp天线它就没有这个匹配段，比如pac-12
我做了个鱼竿天线，如果参考这个图的话，我就需要给它整个匹配
但是实在不太理解这个匹配段的实际作用和道理，故此请教

bl7ia 2021-12-03 22:53
这个是 40 /80米 gp 匹配  

bi4mhd 2021-12-04 10:20
最近我也看到这种天线很火，我也一直弄不明白，为什么我的全尺寸天线不要这个匹配，而缩短了的要

BG1HAS 2021-12-04 14:08
貌似就是在M座那里并联个电感，降低噪声用的吧？

bh9feh 2021-12-04 19:58
是不是可以理解为，有加感的天线就要匹配线圈，没有加感的天线就不需要匹配线圈

刘子虎 2021-12-05 11:32
最近对这个也感兴趣，搜索了一下。叫做发夹匹配，英文名 hairpin match,  beta match ,shunt match.   好像是用在缩短型天线，匹配阻抗的。
http://on5au.be/content/a10/ant28.html


The beta match appears to be simply a small coil or hairpin placed across the terminals of an antenna, most often a Yagi. Some folks mistake the coil for an RF choke, while others mistake the hairpin for a short circuit.
Actually, the beta coil or hairpin is one part of an impedance matching circuit, where the remaining elements are invisible, if you do not know what to look for. Many Yagi antennas have feedpoint impedances in the 20 to 35 Ohm range, somewhat low for feeding directly with coaxial cable. We need to raise the impedance to 50 Ohms--and that is what the beta match system does.
The coil is not the only element in the circuit. There is also a capacitor--or, more correctly, some capacitive reactance. We get that part of the circuit from the antenna element itself.

刘子虎 2021-12-05 12:23
https://www.dj0ip.de/vertical-antennas/hairpin-match/
这里解释的更详细。如何制作、调试。
Quarter-wave vertical antennas mounted on the ground typically have an impedance of about 36 Ohms (assuming no ground losses).  However shorter verticals (e.g., base loaded with a coil, or top loaded with top hat wires) typically have an impedance close to 10 Ohms, and at best 20 Ohms.  Typical ground losses in the real world are about 10 Ohms, giving you a total feedpoint impedance of 20 to 30 Ohms.

Often, especially in portable operations, the impedance appears higher but that’s because the ground losses are higher and the SWR meter is seeing the sum of the antenna’s own impedance and the additional ground losses.
Reducing ground losses by improving the radial network will result in a more efficient antenna, but the SWR will be even higher.  You can address this by deploying one of the following options.

Here are your options:
  • Do Nothing (use it as it; not a good option except maybe on 160m)
  • Use a Matchbox in the Shack. (not the best option, but it works)
  • Use a 4:1 UNIN (this might work, depending on the impedance, but it can be expensive for high power)
  • Use an LC Network with a series Inductor and a Capacitor shunted to ground on the coax side of the L.
  • Use a Hairpin Match  (simplest option)

bh9feh 2021-12-05 13:10
刘子虎:https://www.dj0ip.de/vertical-antennas/hairpin-match/
这里解释的更详细。如何制作、调试。
Quarter-wave vertical antennas mounted on the ground typically have an impedance of about 36 Ohms (assuming no ground losses).  However shorte .. (2021-12-05 12:23) 

大概看了一下，意思是说，由于一些便携天线，其阻抗往往比较低，有的是三十几欧，甚至十几欧，所以要用阻抗匹配器来解决这个问题。
在做它的时候，小功率用2mm铜管或铜线，大功率用3~4mm铜线。线圈直径做成7~10厘米，缠绕10~12圈，并接在天线根部振子和地网之间。
在具体测试调整时，可以调整线圈间距、线圈圈数，一边调整一边看驻波变化。

--------------------------------------------
以上是我看原帖得到的一些信息，不知道有没有翻译错误的地方。
根据这个来看，如果天线本身阻抗是50欧，就不需要这个匹配器。不知是否正确

刘子虎 2021-12-05 14:06
我理解的和你一样。看网上有的老外用鳄鱼夹短路，把这个匹配线圈也做成可调的。上面是可调的加感线圈，下面是可调的匹配线圈。

bh9feh 2021-12-05 15:18
刘子虎:我理解的和你一样。看网上有的老外用鳄鱼夹短路，把这个匹配线圈也做成可调的。上面是可调的加感线圈，下面是可调的匹配线圈。 (2021-12-05 14:06) 

好的，非常感谢你！

bg6sqh 2021-12-09 16:11
学习了，一直不明白匹配线圈的作用，现在有点点明白了

BD7RL 2021-12-09 16:49
纯GP天线振子是四分之一波长，阻抗是50欧姆，而振长比四分之一长或短的，阻抗都不同，需要进行阻抗匹配。

bh9feh 2021-12-09 22:39
中部加感加到1/4波长的，算不算


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