I had the same issue with a sine wave form on the VNA, I've read up as much I as I could and found that on this frequency 868Mhz the coax plays a big role , the best practice is to make sure your coax cable have the right length calculated. To do that work in half wave lengths of the frequency up to the length you need and then add a quarter wave for the last peace. you can do a simple test by connecting a 50ohm dummy load to the cable length and if the coax length is not right you will still get that sine wave form on the VNA. with right length coax you won't get that that.
Why did you put the unshielded element on the end? Did you try it without that element? I'm wondering if it caused the assymetry in the VSWR, since it's a different wavelength.
And from which matherial is tube made of? Because I found on the net that for calculation of the tube length you need tube velocity factor. Maybe Im wrong...
yep this tosser is a flim flam artist.. when did you last see anyon worth salt .. test any antenna flat on the ground or table top Close to metal wood and other definitely interferent stuff what the frack is this broken lightbulb pumping out..
@@viocaia you can´t be a ham or electro engineer you do not know the first thing of any thing do you.. why do you say that 75Ohm tv cable in a pipe would give even better results.. are you mentally challenged ... or do you just get bright idea´s while chugging along???
Hey👍 Thanks for your nice Video. I have a question to your drawings at the end of the Video. Every cable peace should be 150mm to get the 130 shielded right?
@@viocaia Ahh🤙🙏 Thanks for your quick answer. I will start right know to build 😁 I will try this antenna for the helium network on 868mhz the stock antenna is really bad. VNA is still a bit hard for me to find the setting to see the dbi reading.
I theory the same formulas and different velocity number , there are so many variants of this kind of antenna.. I used this one..e.pavlin.si/2018/04/03/colinear-antenna-for-868mhz-lorawan-gateway/
rg58 or any RG cable for that mater is not same Velocity Factor just add´ed almost all RG types are .66 in velocity NOT 75 AS THIS BRIGHT LIGHT NOTES ON PAPER as LMR400 CFD400 or any other RG cable´s (.85V.F) CFD400(.85V.F)
Because I realized that I got my swr down when put plastic around the connection from feed to antenna 😂 I accidentally understood the importance of the quarter wave🤪
@@viocaia Do you recommend this collinear coaxial antenna for rural application? I live on hill 30 km from massive city which is 70 m lower than my house is.
I was thinking about 8dbi diy panel antenna made of steel plates and coax wire. Directed to that city. It has thousands hotspots in it. What do you think?
Виорэл, научитесь сначала понимать, что означает волнистая линия на ВНА, а потом учите людей как делать антенны. Во-первых, кабель для такой антенны должен иметь ОДИНАКОВУЮ диэлектрическую проницаемость как внутренней, так и внешней изоляции, иначе фазы рассыпятся. Потом узнайте, что диаметр четвертьволнового стакана должен быть раза в 3 толще оплётки кабеля.
Собирался делать антенну по данной инструкции, взял ВНА попользоваться. Подскажите тогда, что не так? Какой кабель лучше взять, как понять по ВНА, что частота не та?
You are absolutely right! I just follow some instructionals from the Internet...but be free and let us know a good schematic and what kind of parts and cables we need for a proper job. Thanks Bob!
@@sandwichedman Сначала надо изготовить"мерный" кабель на нужную частоту. "Мерный" - означает, что он имеет целое число полуволн нужной частоты с учётом коэффициента укорочения для этого кабеля. Вычисляем длину N полуволн для нашей частоты, отрезаем, на один конец кабеля припаиваем разъём сма, ответный к нановна. На нановна выставляем измерение реактанса, подключаем к нановна, оставив другой конец кабеля незамкнутым и смотрим на какой частоте имеем максимум реактанса. Укорачиваем кабель, пока максимум не станет на нужной нам частоте. Потом к нашему мерному кабелю подключаем полуволновые отрезки кабеля и так же гоним максимум в нужную частоту. Когда отмеряли два полуволновых отрезка кабеля, то спаиваим их перекрёстно и так же гоним максимум на нашу частоту уже двух спаянных полуволновых диполей и так все следующие. Четверть волновый диполь отмеряем закоротив другой конец кабеля. Запорный четвертьволновый стакан делаем из металлической трубки, внутренний диаметр которой в 3,6 раза больше диаметра оплётки кабеля. вырезаем из медной фольги донышко стакана и тщательно пропаиваем его к торцу трубки и оплётке кабеля. Потом измеряем КСВ нановной.
@@RZ6AT Спасибо! Не понял только момент "так же гоним максимум на нашу частоту уже двух спаянных полуволновых диполей". В данном случае подгонять, укорачивая отрезки симметрично с двух сторон?
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I had the same issue with a sine wave form on the VNA, I've read up as much I as I could and found that on this frequency 868Mhz the coax plays a big role , the best practice is to make sure your coax cable have the right length calculated. To do that work in half wave lengths of the frequency up to the length you need and then add a quarter wave for the last peace. you can do a simple test by connecting a 50ohm dummy load to the cable length and if the coax length is not right you will still get that sine wave form on the VNA. with right length coax you won't get that that.
Thank you, very useful!
In the end when you tuned antenna, did you short the central conductor of antenna to shield of cable?
No, it's the way it comes from schematic..the whip tip is connected to the shield of feed line..
Hi Viorel. What is the gain of this antenna? How many dbi? How you change dbi value?
With 6 elements is 7.8dbI, you can change by the number of elements, always even, 2/4/6/8...aftre 8 is not really gaining more ...so max 8
Why did you put the unshielded element on the end? Did you try it without that element? I'm wondering if it caused the assymetry in the VSWR, since it's a different wavelength.
I follow the schematic I found on the internet...there are lots of schematics, just Google.
And from which matherial is tube made of? Because I found on the net that for calculation of the tube length you need tube velocity factor. Maybe Im wrong...
In fact it should be an empty coax piece, just the mesh ,I found easier to use a telescopic antenna piece..it's cooper under the chrome..
yep this tosser is a flim flam artist.. when did you last
see anyon worth salt .. test any antenna flat on the ground or table top
Close to metal wood and other definitely interferent stuff
what the frack is this broken lightbulb pumping out..
What do you think, a copper pipe and the inner wire(with that white insulation) from tv cable would be good to build such an antenna?
of course..even better results
NO IT IS 75OHM so changing the shild/jacket to a
pipe still make it 75OHM
@@viocaia you can´t be a ham or electro engineer
you do not know the first thing of any thing
do you.. why do you say that 75Ohm tv cable
in a pipe would give even better results.. are
you mentally challenged ... or do you just get bright
idea´s while chugging along???
VNA is back! 🎉
Yuppi|! Just mine too!
@@viocaia i was talking about yours! Mine is still in transit...
Hey👍 Thanks for your nice Video. I have a question to your drawings at the end of the Video. Every cable peace should be 150mm to get the 130 shielded right?
Yes..it have to be longer to have enough room to cut the tip, but the shielded should be 130
@@viocaia Ahh🤙🙏 Thanks for your quick answer. I will start right know to build 😁 I will try this antenna for the helium network on 868mhz the stock antenna is really bad. VNA is still a bit hard for me to find the setting to see the dbi reading.
So, everything is together 👍 I don’t understand my readings on the VNA😩 Unfortunately, I can’t put a picture of my readings here in the Chat
@@noxisworld send it to my email.. viorelcaia@yahoo.com
@@viocaia email is on the way 👍 Thanks
If we use LMR 400 do we have to use the same dimensions according to the scheme? If not, where can we find a schematic for this cable?
I theory the same formulas and different velocity number , there are so many variants of this kind of antenna.. I used this one..e.pavlin.si/2018/04/03/colinear-antenna-for-868mhz-lorawan-gateway/
rg58 or any RG cable for that mater is not same Velocity Factor
just add´ed almost all RG types are .66 in velocity
NOT 75 AS THIS BRIGHT LIGHT NOTES ON PAPER
as LMR400 CFD400 or any other RG cable´s (.85V.F) CFD400(.85V.F)
Hi. Can you help me, how to calculate the size of elements depending of coax cable I have. Thanks
Just follow the schematic
Strange: you can't test an antenna lying on your workbench like that, the vna says it isn't working at all. If it were mine. i'd bin it.
Right..
Hello again , could you tell me the material for the 1/4 wave tube of 56mm?
It can be a piece of coaxial cable..just the shield..I used a telescopic antenna part..from recycle bin...
@@viocaia So it could be also out of plastic?
Because I realized that I got my swr down when put plastic around the connection from feed to antenna 😂 I accidentally understood the importance of the quarter wave🤪
@@noxisworld Never stop learning..me too!
@@noxisworld yep
USUALLY YOU USE SIMIRIDIG OR 1/2" CABEL
It's RG45...check the other videos...
@@viocaia please .. (look again no rg45 in any book i own that´s a 100%no) i won´t comment on that bro.
@@kennethschultz6465 sorry , my mistake it's rg58 LOOK AT 2:56 HERE ruclips.net/video/WDCsK73SC4c/видео.html
You can put the scale down for better resolution.
Thanks!
What copper tube diameter works best for 868 MHz antenna?
I see a lot of antennas using 10mm...
@@viocaia Do you recommend this collinear coaxial antenna for rural application? I live on hill 30 km from massive city which is 70 m lower than my house is.
I was thinking about 8dbi diy panel antenna made of steel plates and coax wire. Directed to that city. It has thousands hotspots in it. What do you think?
@@Fosgen It should be nice..what about a TV Yagi..have you ever tried?
@@Fosgen With this antenna I've been reach 45Km on TX..but not so much RX, it have a more local donut ,like 10kM MAX..You need something directional..
Виорэл, научитесь сначала понимать, что означает волнистая линия на ВНА, а потом учите людей как делать антенны. Во-первых, кабель для такой антенны должен иметь ОДИНАКОВУЮ диэлектрическую проницаемость как внутренней, так и внешней изоляции, иначе фазы рассыпятся. Потом узнайте, что диаметр четвертьволнового стакана должен быть раза в 3 толще оплётки кабеля.
I will!
Собирался делать антенну по данной инструкции, взял ВНА попользоваться. Подскажите тогда, что не так? Какой кабель лучше взять, как понять по ВНА, что частота не та?
You are absolutely right! I just follow some instructionals from the Internet...but be free and let us know a good schematic and what kind of parts and cables we need for a proper job. Thanks Bob!
@@sandwichedman Сначала надо изготовить"мерный" кабель на нужную частоту. "Мерный" - означает, что он имеет целое число полуволн нужной частоты с учётом коэффициента укорочения для этого кабеля. Вычисляем длину N полуволн для нашей частоты, отрезаем, на один конец кабеля припаиваем разъём сма, ответный к нановна. На нановна выставляем измерение реактанса, подключаем к нановна, оставив другой конец кабеля незамкнутым и смотрим на какой частоте имеем максимум реактанса. Укорачиваем кабель, пока максимум не станет на нужной нам частоте. Потом к нашему мерному кабелю подключаем полуволновые отрезки кабеля и так же гоним максимум в нужную частоту. Когда отмеряли два полуволновых отрезка кабеля, то спаиваим их перекрёстно и так же гоним максимум на нашу частоту уже двух спаянных полуволновых диполей и так все следующие. Четверть волновый диполь отмеряем закоротив другой конец кабеля. Запорный четвертьволновый стакан делаем из металлической трубки, внутренний диаметр которой в 3,6 раза больше диаметра оплётки кабеля. вырезаем из медной фольги донышко стакана и тщательно пропаиваем его к торцу трубки и оплётке кабеля. Потом измеряем КСВ нановной.
@@RZ6AT Спасибо! Не понял только момент "так же гоним максимум на нашу частоту уже двух спаянных полуволновых диполей". В данном случае подгонять, укорачивая отрезки симметрично с двух сторон?