Posts Tagged ‘Yagi’
Simple yagi for wi-fi router
February 8th, 2017 | 
Author: This was first seen some weeks ago and I saw it earlier today in an email from Twitter. It shows you how to make a simple add-on yagi for your wi-fi router.
In my case I get sufficient range with the router “as is”. You might find it useful if you need to increase the range in a certain direction. It is a simple idea, which I like.
See https://hackaday.com/2017/01/24/a-simple-yagi-antenna-for-your-wi-fi-router/ .
Worst snow winter since 1958 and an indoor Yagi antenna
Norway has had its fair share of precipitation this winter. Along the coast most of it has been in the form of rain. But that is different in the mountains. Our cabin at 800 m above sea level is now about to disappear in the snow and we can hardly see out of the windows anymore. This is a result of having had to shovel the snow off the roof three times so far this winter. And there is yet more to come.
They say that one has to go back to the winter of 1958 for more snow than we have had this winter, and we are still only in February. The snow has also given us an unexpected problem. Our digital TV signal is now gone.
The TV transmitter is at Mount Gaustadtoppen at 1883 m ASL which is about 10 km to the North and with almost free line of sight. It used to be possible to receive the signals from the national TV provider (Riks-TV) with just a simple indoor dipole, i.e. two wires each of length 13-14 cm connected to a coaxial cable. But not so anymore after all the snow has accumulated outside the windows.
Therefore I had to find a good Yagi-antenna calculator and make a better antenna. I put it on a cardboard of length 45 cm and used the antenna calculator of K7MEM (Martin Meserve). It is a little hard to figure out the exact frequency as there are 5 multiplexes in the TV system and for that particular transmitter they range from 506 to 620 MHz (http://www.finnsenderen.no/finnsender). I therefore just designed the antenna for the multiplex in the middle, 563 MHz. The wavelength is 53.3 cm and typical antenna element length is half of that.
The antenna calculator gave me a design with one reflector behind the receiver element, and four directors in front of it. In the picture, the reflector is to the left and the antenna points to the transmitter to the right.
I made the elements from thick wire, and just taped them to the cardboard. The connector to the coaxial cable is under the cardboard and attached to the center of element two from the left – the one which is split into two.
The Yagi antenna was first described by H. Yagi in the paper “Beam Transmission of Ultra Short Waves“, (Proceedings of the Institute of Radio Engineers, 1928). But as the contribution from his colleague Uda was at least as great as Yagi’s, the antenna should really be called the Yagi-Uda antenna. I seem to remember that Uda could not write English (both of them were Japanese), so the article was written in the name of Yagi only.
But what about my Yagi, eh Yagi-Uda antenna, did it work? Yes, actually it did! With digital signals there is a threshold effect and above a certain signal level the signal quality quickly goes to 100% with a low BER (bit error rate) and with this antenna I came above that threshold. The gain of this antenna is in the order of 8 dB or about 6 dB more than the old single element antenna. Luckily, that was enough to compensate for the attenuation through the snow pile. And as you can see, one doesn’t need aluminium to make a working TV antenna.
[In Norwegian: Verste snøvinter i manns minne og en innendørs TV-antenne]
Antenna up ready for UKAC 144MHz
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| The antenna this morning |
I should say my brother has took his foundation exam and has the callsign M6GTD, so am expecting him to ask for his antenna back at some stage! ;-)
This evening is this months 144MHz UKAC contest and I spent yesterday evening getting the antenna set up properly so I could take part. Unfortunately the antenna was damaged just before Christmas and I have now replaced the boom insulators and straightened the bent director element.
It took a while to get the antenna VSWR down to a satisfactory level, not due to any fault but simply I had the adjustable sections of the active element loop too far out. They are now almost fully in, but at 144MHz the VSWR is a little over 1:1 and across the entire 144-146MHz the maximum is around 1.3:1 so I am hoping it preforms reasonably well, even with 10m of RG-58.
As suggested I have a 'ugly' rf-choke inline, which you can see on the photo. The antenna is clamped just under the vertical collinear, and hopefully this won't affect its performance.
I can put the pole up to around 5m, but the top section isn't that substantial and has a reasonable loading with the yagi and the collinear on it, but the pole it is securely guyed so for temporary use should be okay. Well that is what I thought till I saw the weather forecast
The wind speed and gusts look a little worrying, peaking at around 40mph between 21:00 - 00:00!
The only saving grace is that I will be manually rotating the antenna I will be out checking on it regularly during the contest!
Best of luck everyone taking part...
Six Meter Summer
My Buddipole Antenna, Configured as a 2 Element Yagi for 6 Meters
The ribbons are to keep me from poking my eyes out on the end of the whips.
Here, I’m trying the antenna out in my driveway before I take it to the beach.
Kx3 QRP Radio
Six Meter Summer!
This pavilion is my favorite operating spot at Hagen’s Cove.
It overlooks Dead Man’s Bay, on the Gulf of Mexico in Perry Florida.
I’m going to spend the summer playing around with my Kx3 on 6 meters. The antenna here is a Buddipole, configured as a 2 element Yagi. Its easy to assemble in the field, so I’ll take it to the beach (Hagen’s Cove) and try to make some contacts with it. I’ve been a ham for 22 years but have never done much with 6 meters. This will be a 6 meter summer for me. Join me, I’d love to have a ham radio buddy to share the adventure with.
de AA1IK, 73
