Low-cost DIY shortwave GP antenna (materials list)

BH5UNT

其实市面上有好几家卖成品的GP天线了，很美观，打出了品牌，评价都挺好。虽然价格稍微有一丢丢高（毕竟开模、冲压、钻孔成本摆在那儿。大家懒得折腾的可以买现成的。）

不过我看了一圈都是M头，对于BNC接口爱好者来说就没法用。那么我就带来一个简易的低成本DIY方案，性能不输成品天线，虽然外观有点点丑。成本在100-110元的样子。很抱歉图片手头没有，回头补。

所需材料：

拉杆天线（M10头，大约有十几节，伸出总长度5.6m。材质应该是201不锈钢，收缩起来53cm左右）（最好买有二次加强筋的，稳固不易坏），55元。
绝缘子（例如型号SM7120 M10），8元以内。——作用是隔绝振子和地网部分。
BNC母头免焊快接转换头，大约3元/个——BNC母头部分连接BNC公头的馈线。另一端（快接部分）插压两股电线①和②（横截面2.5平方毫米的BV线就行了，大约需要15cm）；
圆形接线片 2个，大约6元/10个。 ——一片焊上①线，用于馈送射频信号（放在拉杆天线的根部，旋压在绝缘子顶端），一片焊上②线，用于将馈线绝缘层接入地网（旋压在绝缘子底端）
地锚（地钉），M10接口，大约8元/支。
地网（16股排线* 5m，带圆形接线片和热缩管），20元。——这个可以购买成品，到手后按需撕成2股* 8条，或者4股* 4条。

使用时，地锚将 地网的圆形接线片 同连着②线的圆形接线片一起旋压住，本质上是让馈线的屏蔽层通过快接头-②-圆形接线片接入地网。

整套材料除了两个圆形接线片需要焊上电线外，其他都是可拆设计，方便携带外出。不同波段，通过将振子拉出不同长度来灵活切换波段，建议先拉最细的，再依次拉较粗的，避免拉杆天线头重脚轻。

有条件的可以用激光在拉杆天线节上蚀刻每个波段应拉出的位置刻度。（没条件的大概可以用油性马克笔标记，或每次架设时配合VNA微调确认）

注意伸缩拉杆天线、绝缘子上下接口、地插的尺寸要一致，我这里都选了M10，因为拉杆天线是M10头的。如果不是插在地里，而是用相机支架或灯架等作为稳固基座，那么就不需要地插，但要再买个M10转3/8接头之类，灵活改装。

另外我看到地网一是用打孔的法兰垫片（直径约10cm，边缘打4-8个孔，中间一个M10孔。边缘的孔用燕尾螺母压接相应数量的地网），长得很像雨伞内部的样子，这个可能得和商家协商定做。

关于地网长度，众说纷纭，从1波长到1/20波长都有。个人认为5m足够对付7Mhz-28Mhz了。另外地网也可以不一定用排线，可以因地制宜，用网线芯，甚至沿海地区HAM可以用富有海水浸润的海滩作为天然地网也可（小心盐分腐蚀）

另外，振子5.6m长度上限决定了它最低只能工作在14Mhz频段。如果想要10Mhz就需要多装一节振子。7Mhz的话振子实在太长不安全，只能采用加电感的方法。加感线圈的设计计算可参考BG8NSK的excel表，非常详尽。

BH8GIO

BH5UNT
Hey everyone, if the cost is around $110, then your product is actually quite expensive.😡

However, I believe that if you do it yourself, it's definitely worth it, and it also meets a variety of needs.
Upvote for the original poster.👍

BI9CBD

BH8GIO 35 What is this? Isn't the main post about a property for sale at 110, and that particular listing was for around 300?

BA7NNC-JOE

BH8GIO 35 pieces... a complete set of over 300. 🤣 There are also some that start from around ten yuan each, and once you enter, there's a whole area filled with them. 🤪

BI9CBD

This is perfect timing! I was just thinking about setting up a GP antenna recently. I'm also curious, what specifications are the circular connectors? And how does the antenna perform?

BH5UNT

BI9CBD Inner diameter: 10.2 mm, tin-plated, 0.8 mm thick; wiring size: 2.5 mm²._{4 mm²} 。
The results are quite good; the standing wave is within 1.1!

BD3OZV

I recently installed one myself, on the roof. The coaxial cable's shielding directly connects to the iron support of the building's solar water heater. This support is connected to the lightning protection system. Although there is some shielding nearby, the effect is still quite good, and I can easily adjust it using nanovna.

Hangying

That's great! DⅠYER can still be used for a while.

BD8DIN

The most expensive part to manufacture is the telescoping antenna. If it's fixed, consider replacing the telescoping antenna with a plastic support pole and silver-plated wire, which would further reduce the cost by tens of yuan.

BD3QCY

I also use a 5.6-inch pull, approximately 45 inches long.
Ground stakes, approximately 30cm long, with a diameter of 5.62

The GP base is 3D printed (consider using a JiaLiChuang 3D printer).
Along with the M10 thread and nut, the M seat, and a short piece of electrical wire.

The ground wire consists of steel cable coated with rubber, and banana heads welded to it using toilet bowl cleaner.
304 red plastic film, 2mm thick (10 meters) x 2, approximately 10 pieces.

BG8KUQ

The handle gets wet from rain outside, and water can get inside. It's quite annoying.

CQ-BG8LTU

I bought my first GP base on Xianyu from a seller in Harbin, using China Unicom's Castle.
The 60 RMB includes the base, ground stakes, and five ground wire lines. You can then purchase an additional pull rod to use it.
The total cost is less than $110.

BH5UNT

Missing a material:M10 nut (Used for tightening ground stakes and providing electrical connections between the ground stake, grounding wire, and feeder cable.)
Previous diagram:

(On the left side of the insulator, there is a pull rod; on the right side, there is a grounding stake. A grounding wire ring should also be attached to the right side, and connected using the above.)M10 nutTighten

BI1MXY

BH5UNT If you don't understand something, ask why it's not a ground wire connection instead of a signal wire connection for the lever?

BG5JKZ

I excitedly placed an order, but I realized that the ground nails and M10 nuts are not needed, so I searched for "M10 * 300 tube nails" to cover both the nut and the ground nail, which only cost 4 yuan.

BH5UNT

BI1MXY I didn't explain it clearly enough. The signal wire is connected to the pull handle (via the positive terminal of the quick connect). The ground wire is connected to the shielded cable (via the negative terminal of the quick connect).

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