Collinear Antenna for 2 4GHz
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- Опубликовано: 16 дек 2021
- The collinear antenna is a common omnidirectional antenna that is capable of being stacked to achieve higher gain. This is part 1 of 3 videos where we build three of the most common build variants then we will have a shoot out to see which is best!
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I've played a lot with collinear and basically given up on them.
1) If they are badly tuned on initial build they are basically impossible to fix without complete rebuild, which gets expensive.
2) The physics of them is dubious. You cannot avoid having phasing issues as the velocity factor inside the coax is different to the velocity factor of the external tubing.
3) The required gaps between segments, god knows what that does to the signal.
4) Your ground plane is OK, on reading they recommend around 4x the diameter of the inners. A spider arrangement maybe better?
All in all a great build video. The insulated end is fantastic discovery. I really look forward to the other build vids and final shootout.
I tend to use K&S Metals 4mm tube. (LMR200 coax fits super snugly in it) I have lots of photos of build bits if interested.
would love to see them can join the facebook group and share them
@@andrewmcneil Merry Christmas Andrew. I would but I refuse to use Facebook sorry.
so what type antenna would you recommend for an omni design (not for super-long-range, but for a more 360degree coverage rather)?
During the construction of a coaxial co-linear antenna u have to get the decoupling section right! are you will have issues.
I have found every colinear i have built is inferior to to the standard alfa rod.
Great work Andrew. Antennas are mythical.
Great video. I enjoyed the clear and methodical explanation and illustration. However, I’m a bit disappointed with the end result. The first frequency response curve indicated a higher Q, and I was hoping you would have tried retracting the top piece (to make the overall length shorter) but instead you were focused on trying the isolation approach and never tried what I think could have turned out to be a better solution. I plan to build one of these for ADS-B reception (1090 MHz) based on this design and will try the adjustment I mention above. And, If I can find this video again after I’ve done that, will return to post my findings here. Thanks for sharing!
I'm a bit confused. In your older videos, you mention the half-wavelength of 2.4 GHz as 25 mm but now it's 31.5 mm. I imagine this question comes up a lot, but could you perhaps explain why you use those lengths?
Is the rigid tubing simply for mechanical strength or does it drastically affect the transmission properties of the antenna? We’ve all seen these built with coax alone. How does this compare with a coax- only version?
So if you dropped the feed element down to 30 mm, then cut the tubes from 55 to 50 mm (50+8=58mm) = half length B41 LTE Signal? B41/n41 operates at 2496-2690 which at 1/4 is is between 30.027 an 27.862 mm by the math. So would that even work with LTE, or would shaving off 1/11 of the length mess up the balance?
Hello Andrew sir I hope u well. Sir haw do I make biquad antenna with multiple frequency please suggest me some thing I'm interested to make for satellite TV dish please sir thank you
wait, you could use pieces of thick coax, instead of the pipes?
Would it be possible to lengthen the elements a bit and not insulate the end cap to get an antenna with the first profile but at the target frequency?
what's the gain? dbi?
How can I regulation it for 868mhz.
You don't want to melt the insulating part of your socket or you have to start again maybe conductive resin might have been better isopon resin plus copper powder so the insulating part of the socket is not damaged.
But, what is the point of the brass tubes around the coax? The coax shielding would do the same thing, right? You are going to put the whole thing in a PVC tube in the end anyway (for rigidity)
Accuracy in measured lengths. Its been done with just coax but you end up with a snake that can possibly be shorter or longer once in tube. Brass is just neater and can be cut far more precisely.
On a separate note, this is a 2-wavelength antenna, correct?
Staggered resonant tubular capacitors
Failure to compensate for velocity factor. You numbers are based on lightspeed velocity, that simply does not exist in any conductor. The brass is going t be around .96-.97 making the correct 1/4 for brass 31.28mm That cable of unknown type is hard to determine without the type number. If it is a typical solid poly then the vf is around .66, meaning the correct 1/4 wave is actually 20.61mm. If it's a foam it can vary much, but typically is around .80 making the correct 1/4 wave 24.98mm. Your antenna is just too long, and any in-band radiation is likely only from the isolated 1/4 wave at the top.
You don't need the brass tube, the coax alone works just great.
I have built a more than a few collinear antennas from 50mhz to 5ghz, and gotten great results using far simpler technique. Your workmanship is great, but you have to remember that there is no single number more important than the velocity factor if you want it to work right.
i find using separate flux helps quite a lot
Yeah, big copper tho, cooking it a bit helps. Even a gas hot air gun helps.
Unfortunately I am allergic to flux even with a N95 mask!
Andrew? @11:42.....You transfered solder from Iron 2 antenna? Obviously, doing that normally is'nt reccommended, due to the solder's flux getting burnt off. So doesnt the solder have a harder time adhering to the metal, this way?
Btw..as always, you rock regarding Wifi & Antenas.
I am super allergic to flux so sometimes I will use methods to get around using it.
@@andrewmcneil cheers bud
Dumb question time.... this was an omni direction antenna right??
Yes
yes
What kind of PVC tube do you use ??
I tried gray color PVC tube . And it effects the antenna resonance so much .
I have never seen grey I only use white
Grey has carbon in it I believe which is conductive and hence interferes. Black poly is also full of carbon. White seems to be fine.
Thank you so much . I will try white one . Yes gray tube heats up little bit in microwave oven .
i was looking all the hardware stores here for white tubes . They have only gray tubes . 🙁Maybe white not available here . Are there any other alternative for this ???
@@kavindugilshan Hrm I'm guessing you tried reticulation and plumbing sections. Weird most of ours is white.
You can try any tubing. If it warms up in microwave its no good.
Hobby stores may sell fibreglass tube but most are now switching to carbon fibre tubing which is no good. Its expensive tho. Try a reticulation store?
HELLO ANDREW, could you make the same antenna but with sma connector? 😊
Tomorrows video!
For 4g multiple frequency
No
Can you help me please
Yep i certainly can, for a small fee, lol
😁
that looks like a lot of work for a monopole with delusions of grandeur.
Gain stacks at diminishing returns as you add segments. Six-eight is the apparently optimal number.
Agreed
Are you even fair bro why can’t you reply, I need help with fixing my dish internet man, can you help??? Just say no if can’t and I’ll understand
Quit acting like a child.
This is so tiresome and a blatantly incompetent protocol of antenna experimentation.
No element modeling
No element development before assembling an array.
No array modeling.
This entire channel is a toxic waste.
What are you talking about? Where you born thick or is it something you aspire to be? Channel is 14 years old with millions of views what’s on your cats? This is a practical channel if you want modelling and simulations go find them there are some that get 4 views a week.
I take that back you’re a ham radio knob aren't you
Amazing as always dear, i hope you can give me a way to make 4G antenna for different frequency 1600mhz and 1800mhz, any help is appreciated 😀
Will try