如题，一个月前就想搞个八木天线，各种仿真，优化，买材料，东西到齐很久了，但拖延症是真的伤不起。今天终于下定决心干活，１个小时搞定，求各位多多指教。 [upl-image-preview uuid=4aae4a6c-77d8-475f-ad0f-8f80531e4bdf url=https://storage.hamcq.cn/2025-09-10/1757486170-250093-img-20250910-141737.jpg alt={TEXT?}] [upl-image-preview uuid=34ea5134-11ee-4ee4-862b-47448f933af1 url=https://storage.hamcq.cn/2025-09-10/1757486162-742563-img-20250910-141745.jpg alt={TEXT?}] 材料清单（某宝）铝管 Φ4Ｘ1000ｍｍ３根 11.7元木方 26X20X1000ｍｍ 1根 0元买铝管送的管夹 M3-4 10个 1.48元只用了4个馈线 50-3 5米 11元只用了1米亚克力圆盘 Φ80X4ｍｍ１块 0元从犄角旮旯里面翻出来的，随便用个塑料也行接头 SMA－K－３２个 4.6元只用了一个，另一个备用 **合计** **29元**

@"BG5GDP"#p78291 手头上没有天分，另外买的接头也还没到，等连上接头拿到楼下暗室用矢网测一下，应该问题不大，之前仿真的结果是相当好

相片呢？仿真和实际做出来会有一点差别，最好能测试一下。

@"BG7MGW"#p78293 仿真结果放在之前的帖子里了，找个时间接上矢网看看

@"BG7LJX"#p78295 感谢感谢，另外，给您回的卡片是9月6号寄出的，希望能顺利到您手中

然而，仿真的结果，可能和实际相关甚远，并且，实际测试时，周边建筑物及天线高度，对结果影响极大。

@"redeva"#p78317 是的，而且v段频率一般的暗室还测不了，V段吸波所需的尖锥高度一般的小暗室根本装不了几个，只能说凑活着测一下，只要谐振频率不是偏的太厉害就凑活着用吧

@"BI1NIZ"#p78393 平衡转换是什么结构，之前仿真优化的时候是已经把S11降到了-25dB以下，所以正常来说是不需要再增加其他阻抗匹配的结构了，等我今天去测一下驻波看看

I finally managed to build a 3-element V-shaped Yagi antenna that I've been planning for a while!

BG5FUM

As the title suggests, I've been planning to build a Yagi antenna for about a month. I've done research, optimized designs, and gathered materials, but procrastination has really held me back. Today, I finally decided to get started, and it only took an hour. Please offer your advice and guidance.

Materials List (on Taobao)
Aluminum pipe Φ4 x 1000mm, 3 pieces, 11.7 yuan
Wooden block: 26x20x1000mm, 1 piece, 0 yuan (free gift with purchase of aluminum pipe)
Clamp, M3-4, 10 pieces, 1.48 yuan each – only used 4.
Cables: 50-3, 5 meters, 11 yuan each. Only used 1 meter.
Acrylic disc, Φ80x4mm, 1 piece, 0 yuan. Found it in a corner, any plastic will do.
Connector SMA-K3, 2 pieces, 4.6 yuan each – I only used one, the other is for spare use.
Total　　　　　　　　　　　　　　　　　29 yuan

BA4ICQ

BG5FUM What is the spacing between the driving vibrators in mm?>

BG5GDP

Let's measure the standing wave.

BG5FUM

BG5GDP I don't have any special talent, and the extra equipment I bought hasn't arrived yet. I'll wait for it to arrive and then connect it to test with a laser grid. Based on previous simulations, I think there shouldn't be any problems.

BG7MGW

What about the photos? There will be some difference between the simulated and actual results, so it's best to test them out.

BG5FUM

BG7MGW The simulation results are in the previous post. I'll connect the antenna and take a look when I have time.

BG7LJX

Congratulations!

BG5FUM

BG7LJX Thank you very much. Also, the card I sent back to you was mailed on September 6th, and I hope it arrives safely.

redeva

However, the results of simulation may be very different from reality, and in actual testing, the height of surrounding buildings and antennas can significantly affect the results.

BG5FUM

redeva Yes, and the typical dark room cannot measure V-band frequencies either. The small dark rooms needed for V-band absorption typically require a cone height that is too large to accommodate even a few, so they can only be used for rough measurements. As long as the resonant frequency is not significantly off, they can still be used.

BI1NIZ

Adding a balancing conversion would make it perfect.

BG5FUM

BI1NIZ What kind of structure is "balanced conversion"? Previously, when I optimized the simulation, I had already reduced S11 to below -25 dB. Therefore, in theory, there's no need to add any further impedance matching structures. I will measure the standing wave today to confirm.

BI1NIZ

BG5FUM The excitation part involves balancing the feed, but the input signal is unbalanced. Therefore, a conversion is required here. If your antenna is already 50 ohms, then it's a direct 1:1 symmetrical type. Can the simulation reproduce this situation? I haven't figured that out yet. However, according to G0KSC's information:
Ideal balanced power supply:

No:

BG7MGW

BI1NIZ I remember a natural harmonic Yagi antenna that doesn't require an unbalanced conversion.

bg7xwf

BI1NIZ Okay, you've learned it perfectly! The key is to add a "Baren".

BI1NIZ

BG7MGW "Harmonic and balanced are two different things. So, why does a positive voltage need to be balanced?"

BG7MGW

BI1NIZ Or could we also add a Ferrite band to prevent the cable from radiating?

BG5FUM

BA4ICQ 20mm, you can see the specific parameters in my previous posts.

sainata

Hi, I'm also from Huzhou. I'm currently trying to use a Moksen Yagi antenna (but it hasn't worked yet). Can your antenna reach the Hangzhou repeater? DE BG5GJK 73!

bg7xwf

sainata I just heard a BA4 repeater transmitting on 145.400 MHz to Hangzhou this morning.

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