Switchable Array in Two Directions - the Phased Vertical Antenna Array
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- Опубликовано: 1 ноя 2023
- In this video, we progress from the Parasitic array and use the techniques in Phase Angles and Velocity Factor to build a switchable array left/right. This can also be driven without the phasing loop to crate a N/S pattern but personally I don't think it's worth it - and the tuning goes to pot too. OK if you are desperate I guess! Callum.
Links:
• What is a Coax Phasing... Coax Phase Lines and Angles
• What is Coax Velocity ... Coax Velocity Factor
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Good to see Roly there Callum!! 👍👍👍
Yes indeed!
60 years ago, Hy-Gain made a phasing box called, appropriately enough, a Co-Phaser. It was meant to be used with two identical base station vertical antennas set 36 feet apart, I believe.
Some 40 years ago i listened a lot to a 80 meter net. And one guy there told the other guys he would make this for 80 meter in de DX portion. With 4 elements for each direction and a middle element. The whole build took at least a year. He had many daily updates on his project so this was fun stuff to listen too as SWL. And he got it working! And it worked amazing good. When he tested it on air with his buddy's . I was close paying attention to my S-meter. And when he turned to me he had 9+30DB signal. And when he turned away from me he had a S6 / S7. Amazing difference.
Fab!
do you get the 3rd harmonic with this(40m/15m). would be great if it would. thanks for all you do for the hobby. KI7MJU
I've built them in one direction, without being easily switchable. Using two 50 ohm antennas, two quarter wave length pieces of 75 ohm coax on a T-connector from the 50 ohm feedline and then a 50 ohm coax cable from the 75 ohm 1/4 wave pieces to each antenna. One antenna gets a 50 ohm cable 1/4 wave length longer than the other. The one with the longer cable is the direction of the antenna. 1/4 wave spacing between the two elements will give a small lobe on the backside, while 1/2 wave spacing will give a very sharp null at the back. If equal length cables are used for each element, the pattern goes broadside and is bi-directional, but is narrower than the unidirectional pattern of delay feeding of one element. The extreme front to back ratio can found with 1/2 wave spacing and 1/4 wave delay feeding the director element. The two 75 ohm 1/4 wave coax pieces are just to match the 50 ohm vertical elements.
Nice.
I used phased verticals on 40m and on 80m accord the Christman method. They worked great. Some weeks ago I replaced the verticals bei Delta-Loops. Also working great. The biggest advantage compared to verticals: no radials are needed. On 40m the F/B ratio is around 20 dB and the gain of the phased delta loops compared to a dipole is 3-6 dB higher (for DX)
Look at any major am station in the us is a great example of phased verticals. The one here for example has 4 masts that they use to alter the radiation pattern at night so they don’t interfere with other stations
The tricky thing with passively phased arrays is getting the power to divide between them as you expect. If the feed point impedance of each vertical matched that of the coax attached there to, then the length of the coaxes from the antenna to the switch box wouldn't matter, so long as they were the same. But it doesn't match, so this piece of coax is performing an impedance transformation (most easily worked out with a Smith chart). If memory serves, vertical quarter waves are somewhat lower than 50 ohms, so the nearly quarter wave of coax would give a higher impedance. (35 ohm becomes close to 71 ohms, 25 ohms becomes close to 100 ohms.) Feeding them in parallel, such as when the broadside switch (the one that shorts out the delay loop) is closed, the impedance seen by the source becomes more reasonable (35.5 or 50 for the examples in parentheses above). But when that loop is in play, one antenna is seen via 84 degrees of cable and the other via 84+71 = 155 degrees of cable.. So their impedances, both resistive and reactive, will be noticeably different. (Unless the feed points really are 50 ohms.) Good cancellation off the back requires that signal the amplitudes be the same. (You can't wipe out a two penny debt with one penny,) The closer you come to same power, the nicer the null in that cardioid pattern.
Laird Callum... This makes me e think of the broadcast arrays that are directional in my area. If you keep making these videos, I will need 8 DX Comnander clasics with the appropriate phasing cables and a remote switch so I canphase them for gain and switch for durectivity! LoL Perhaps one would then be able to get a QSO from Laird Callum here on the "left" coast of the colonies! Love your videos, and keeo them coming. Not only are you an entrepeneur, but I daresay one heck of an "Elmer".
Wow, thanks
Phased arrays always interested me. I hope you build one and do some practical testing.
Finaly the 2 elm that works😉😉
No more modeling .. get out build one .. film the action
Make set of gp’s ,feedline and fase line and sell them to the world for not to much 💵
Great video brother... thanks for all you do. Callum a couple of quick things.... the impedance of the two elements needs to be as equal as possible to make sure the current divides properly between them otherwise you get varied current reducing the efficiency of the antenna. this is a bit easier to do with an elevated set of verticals and four 1/4 ground plane elements. You can use 75ohm coax, it is probably preferable as if you are feeding two 75ohm loads in parallel, Z1XZ2/(Z1+Z2) = total impedance. At 75 ohms you end up at 37.5ohms impedance for the coax. The antenna will gain in the direction of the delayed element, if you delay A, in theory the signal from B should interact with A in additive interference and create gain in the direction of A. The far field pattern will change with the distance between the elements, also the elements will need to be shortened due to mutual coupling between the two elements.
Top Banana John!
Cal yerraguddun and bloody marvellous with your practical explanations. I’m re educating using your channel because I’ve been off air since mid 90s… making my way back into it. Station in development. Antennas are real interesting. Thanks for doing what you do. 😊
Best wishes to everyone… mind how you go. 73
Awesome, thank you!
Phased antennas can certainly work very well, not sure in the diagram at 2:20 why the 84 degree sections, as long as both are equal the phase is preserved. S1 is presumably intended to drive both antennas in phase which should give you a broadside pattern, an alternative to the two directions of end-fire. S1 should actually be a double pole double throw to entirely take the 71 degree phasing section out of circuit. As illustrated closing S1 will effectively create a 35.5 degree stub. Certainly very interesting. I have never tried phased HF antennas but have done some playing with VHF/UHF phased antennas. The nulls you can achieve in the patterns are amazing, more impressive than the gain! Good Luck
Yeah. I don't know either.. There's a clever chap who commented.. somewhere on this video (read down) but I was in a rush and can't quite put it together..
Great video as always!!
Thanks again!
with 50 ohm coax just a coil will help bring up impedance to 50 ohm. also 75 ohm coax will bring up impedance as well. the delay line as well . 75 ohm like RG 11 . the 75 ohm coax gets you closer to 50 ohm at transmitter the tuner will do the rest or just use a coil to bring up to 50 ohm and no tuner needed if both antenna's are cut in tune the same. at my AM broadcast site we have 4 towers cut the same and fed into phasor that gives us a change in pattern of signal . this also has coils and large vacuum caps to keep transmitter loaded to 50 ohm. this also switches for day/night pattern. great job showing phasing . this is where the length of coax is very important . if only one antenna the length of coax does not matter only the loss in coax . 73's
Nice!
75 ohm coax is frequently used on arrays such as a 4SQ. Because the VF is greater for 75 ohm coax than 50 ohm coax this gives a longer physical feeder length. If this was not done it would be impossible to physically connect the elements to the phasing box at the center of the antenna array. Stewart G3RXQ.
Yeah.. or triple the amount of coax! :)
B*****y Pythagoras !
📐
Interesting.
Hello Bob!
Nice❤
😊
I'm still learning but I think you have a mistake in the model where you set phasing. I've seen references to Christman and they say the harness generates a 90* out of phase signal from the 84/71/84 harness. I still don't know how that works. Intuitively it makes sense as you'd want your 1/4wl spaced antennas to be phased 90* apart so the peak of the "faster" antenna hits the peak of the "slower" antenna. Hopefully someone smarter than me can explain it.
See a later video where John explains all this..
All this works well when the poles are sturdy but what will be if they are flexible and start to bend under the wind load? For sure there will be no 1/4L. By the way, long ago I watched a tube video of some Russian guy that had built antenna field with verticals arrayed and phased. He had even 160m vertical array. But they all were pretty sturdy and heavily guyed ... and crazy high. You can imagine what the size of the field was considering that he had all bands built similarly. :)
With the high current being sat the bottom, depreciating as a SIN wave, you would hardly notice the difference.
Can I vertically mount my TM-33 by turning it on its side and get better DX? Would I need a fiber glass mast to do so? Will it work and what height would suffice?
Unlikely due to height above ground.
Hi, long time listener first time caller here..
Can you please do a bit of moddeling for me, I am curious about using 2 ZS6BKW antennas hooked together but at 90° to each other, I’d like to try two antenna hooked up to the one feed line. I’m trying to experiment with being able to get ZL and North America at the same time from my QTH here in Western Australia.
Is this even possible? Would I need two ladder line sections or could it be done with one?
Honestly, it depends on height above ground and frequency.. Personally, it's a heck of a lot of work and frankly unless you can get AT LEAST around a wavelength above the ground anyway, it would probably be a waste of your efforts. Try a 20m home-brew vertical..?
Thanks yea I will take your advice and try the verticals..
thank you
1 driven ele and 2 parasitic ele gave me 2 S points over 1 driven ele .
Thanks for a great video.
Yes, this setup could be made ( I made one for the 2 band making the test easier as the verticals is small and manageable ), Is this setup worth it? , If you have QRM that ones tries to eliminate than yes, but in a relative QRM free situation the difference on the receiving DX station is not going to be noticed ( no wow what a difference affect) , this situation is to change if more than 4 vertical elements are used ( could be a good idea for the 80m band), when it comes to the higher bands one might be much better with a Yagi.
All i could say is test test test and have fun doing it, there is nothing like knowledge you gained yourself by trying it out, as for the computer modelling ,,,,,, well,,, reality bites over and over gain.
I would only use 75 ohm cable if your antennas are tuned to 75 ohms as well.
Should try 3 or 4 DX commanders phased and pointed in a direction of your choice hihi....
With a third vertical you end up with a Hygain ScanMaster for 40m instead of 11m CB
You would. They were elevated with an interesting matching system I seem to recall.
@@DXCommanderHQ I have the original drawings and the phase harnes's info along with the control box info. kg5pyc QRZ
Add a third element and you got a superscanner .
Little bit wrong spacing between verticals. On your geometry, there is 10.5 meters. By trial and error I found the best value of exactly 10 meters spacing for 40m band.
.. and 8.5m for Parasitic.
@@DXCommanderHQ Thanks. Will try that as well.
Hey Callum. Have you checked the calculations in other antenna programs like for example 4nec2? I trust 4nec2 a little bit more -
Moreover it is important to use antennas, which do not need so many radials --- loops, efhw - etc. Here is my video referring to your video... Best & 73 Thomas
ruclips.net/video/Xq9jd1Qi6uo/видео.html
He shouod build one and find out :)