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.

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!

The proximity of the power meter head will significantly affect the tuning of the collinear. Also, the only thing I ever see on KZfaq regarding the builds of collinear antennas is their SWR, when the only reason for building them is their increased gain towards the horizon. I would think a field-strength comparison of a simple dipole vs the collinear would be the parameter of interest in the construction of one.

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?

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?

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?

Staggered resonant tubular capacitors

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)

i find using separate flux helps quite a lot

wait, you could use pieces of thick coax, instead of the pipes?

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.

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.

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?

Dumb question time.... this was an omni direction antenna right??

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.

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

On a separate note, this is a 2-wavelength antenna, correct?

what's the gain? dbi? How can I regulation it for 868mhz.

What kind of PVC tube do you use ?? I tried gray color PVC tube . And it effects the antenna resonance so much .

that looks like a lot of work for a monopole with delusions of grandeur.

For 4g multiple frequency

HELLO ANDREW, could you make the same antenna but with sma connector? 😊

Can you help me please

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.

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

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 😀