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How to tune a 2 el Yagi or any parasitic array
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- čas přidán 20. 06. 2020
- I do some experiments in the workshop to explain mutual coupling and show how to easily tune any 2 el parasitic array in the field by just using the analyzer to sweep the driven element.
80m-40m Yagi paper:
drive.google.c...
160m parasitic array paper:
drive.google.c...
So for those coming along and wondering about how well this works, I can tell you it does. It really does. That said, I spent a lot of time going over this video and the other xm240 video from Steve to grasp what was being taught. I am not too proud to say I had to listen to these videos several times...there is a lot of information and no Fluff...quite a nice change from some typical 'amateur radio vids' telling you how to program a Chinese 2m rig. I digress.
In the end, I replicated what Steve had on offer here for my 40m yagi at 72 feet--complete homebrew. I have a lovely, but steep, 'real' R dip, and my tuned reflector above the dip-- close to 3 s units gain. Yes, 18db...and I am being conservative because I can hardly believe it myself. Real world tests will confirm, and I will update here if I see otherwise. The sweet spot is around 7064, and between 7040 and 7110, I have over 3 s units gain--both sides of the U- bottom. Measured numerous times using a 0 dbm level signal 1/2 a km away from the antenna...not scientific, but results were repeated numerous times.
Anecdotally, I tuned the afternoon southern Net---all this in the midst of another aurora burst and broad daylight-- so typical this time of year in Yukon, and heard and worked stations I could have only 'presumed' were there that time of day. Crazy. I have tamed my swr to about 1.5 or better between 7.050 and 7.245. If I was an ssb guy, Id be sitting in gravy...I work mostly cw... I could have tweaked more, but my hinge base arrangement needed more attention due to the up and down...for now, I am thrilled.
Many thanks to Steve for putting this out there. I am sharing it with anyone interested in yagi design and tuning.
73
Scott VY1CO
Update: A ham neighbour a few miles south indicates F/B closer to 4 s units (that's approaching 24dbi) . Impressive.
I have had more fun the last couple weeks trying to replicate some of these results…and I’m getting there! The nano van has shown my Real R point to be much higher on the 40m yagi…great videos.
For accurate results, make sure you calibrate the VNA with an OSL to the end of the feedline at the Yagi.
Excellent, thank you! Too bad it took so long for CZcams algorithm to figure out I was on the lookout for it.
I really like this video. The idea of showing exactly how the physical changes to an antenna affect its performance are fascinating to me. I am considering getting my ham license just for that reason.
Steve: Thanks for this. I have been puzzling over much of this (mostly with tuning 2-ele quads) for decades, and this is a real help. --NT0Z
Very clear Steve, you're a good teacher! The little antenna in your shack brings it to life. Cool! 73, Gary ZL2iFB
Thank you! Just what I've been searching for in tuning my home brewed 6M 4el yagi.
I do comms for volunteers doing public safety operations in wild country. Mainly high band VHF. Sometimes they have vehicles but mostly all done on foot: a half-wave dipole is mounted on rucksacks. Simple improvisations that a non-technical person can do to improve comms are gold-dust! Every couple of dB is worth it. After watching this video, two things occur to me.
1. User on foot using half-wave dipole. Helper holds walking pole (Aluminium tube adjusted to 5% longer than dipole) parallel to dipole, 0.2 wavelengths from the dipole, on the side opposite the station called. (Is electrical continuity between the sections of the walking pole an issue?)
2. User with vehicle (with handheld radio and no vehicle fit). The flat metal electrically independent side of the vehicle faces the station called. The user holds the dipole antenna parallel to and 0.2 wavelengths from the side of the vehicle. (A van door might provide a smaller reflector.)
- Thoughts anyone?
Outstanding as usual Steve, thank you. I have been experimenting with 40m 1/4 wave vertical paratisic array antennas for about year now. A few months ago I built a phased parasitic 40m 1/4w array with a reflectors and directors (6ele). This video is a big help on understanding and improving that.
Excellent presentation, Thanks so much N2FH
Thanks for the detailed information. I'm planning to build a Yagi to listen to the air band this info is valuable.
Excellent explanation!
Really helpful, thanks Steve!
Thank you Steve! This was very inspirational. 73 de Kari, OH2XX
WOW! Great video, Steve! Can't believe I haven't come across your channel before! 73 de VE3GKT
Excellent video!!!!
Great presentation, thank you Steve! 👌
Peter, HA8RM
Great stuff.
One thing I wonder about is, should one tune the driven element first to match the impedance from the simulation and then tune the whole yagi as you described?
/Mike, SJ2W
hi, great video. i have a 2 ele 20m vertical array using a driver and a reflector, but always had problems getting them to work any better than a single vertical. I did try altering the length of the reflector and having a fields strength mtr behind the array, hoping to get a big dip, which i thought would say most of the rf was now going forward, but on air tests did not show that. So now I presume basically what you are saying, if I alter the length of my reflector until the swr on the driver is the lowest on the freq i wish to use, the array will be optimised !
will my mfj-259 analyzer show me the correct R value???? it a cheap device and I had to repair it but it works and I dont have much money
Hi Steve,..Thx much for video...How do I use this method for properly tuning my Diy NBS based 12 Element 437 Mhz antenna for Each of Individual 11 Director Elements ? Thx so much...
Can you imagine a mathematical relationship between the R null dip and maximum F/B and Gain ? or this entirely dependable on variations between antenna configuration and type ? My thinking is that you knew a rule of thumb that you could get pretty close without needing a model of the antenna itself. Jonathan GW2HFR
I understand your question. However, as you suggest, I think the relationship between the dip and max F/B or gain will change depending on design details like element spacing and loading.
This is a very nice setup you have here sir
Are you able to calibrate your the feedline with your Aim analyzer all the way to the Yagi connection point?
That must be a lot of Coax?
Hello Sir! First of all i must say this is one of the best explainations i have ever seen on the subject, it has cleared lot of confusions...still there are couple of things which im still not very clear about... I have just designed a vertical parasitic array for the 17m HF band which is only 100 khz wide..after tunning the driver and the reflector(about 200khz lower than the director) when i do the sweep on the analyzer the R remains between 48 and 51 and the X -1.64 to 2.24 so R is mostly a flat line..so how can i adjust the reflector or a director when the R is almost flat on such a small bandwidth....hope i have not asked a stupid question...thanx
What range are you sweeping? Indeed the 17m band is very narrow, but perhaps sweep with the analyzer from 17,800kHz to 18,300 kHz?? The dip should be somewhere in there? Then you can zoom in as needed.
@@ve6wz thanx Sir for the reply, im sweeping 18000to 18200khz
Will this work on a 40 meter Moxon antenna? I am trying to tune a switchable Moxon wich uses coax subs to add inductive reactance when that piece of coax hangs open..73's WA3O
A traditional Moxon is still a 2 element parasitic with the element tips bent in toward each other. You can possibly use this method, but it is vital that you build the model, and understand the relationship between the R dip and the max gain and/or the max F/B. Tuning the antenna is only done by understanding this relationship and measuring/adjusting it in the field.
Ok Thanks for the quick response. Still trying to learn 4nec2 to to the modeling...steep learning curve. I do have a .nec file that was made from someone else However, I am having difficulty trying to figure out the harnesses.
73's
Mike WA3O
Ok I think you are the right person for my question to you, can I get some specification for the, 2,3,4,5 element yagi flat side antenna, i wanted it for the 11meter cb band, I am a cb radio operator who always make my own antenna, please an thanks bro, if you are going to help me, i will send you my phone number for WhatsApp, watching from Jamaica west Indies !!