It is apparent that Yagi did not aim to steal the publicity at all and as a result the design now bears the names of both men and is formally known as the Yagi-Uda antenna. The Yagi antenna design has a dipole as the main radiating or driven element to which power is applied directly from a feeder. Further 'parasitic' elements are added which are not directly connected to the driven element but pick up power from the driven dipole element and re-radiate it.
The phase is in such a manner that it affects the properties of the whole Yagi antenna as a whole, causing power to be focussed in one particular direction and removed from others.
The amplitude and phase of the current that is induced in the parasitic elements is dependent upon their length and the spacing between them and the dipole or driven element. If an element is longer than the resonant length, i. In this way the phase of the currents in elements that are shorter or longer are different. The Yagi antenna exhibits a directional pattern consisting of a main forward lobe and a number of spurious lobes to the rear and the side.
The antenna can be optimised to either reduce radiation in the reverse direction by altering the length and spacing of the reflector or it can be optimised to produce the maximum level of forward gain. Unfortunately the two conditions do not coincide exactly and a compromise on the performance has to be made depending upon the application.
It is necessary to choose either maximum front to back ratio or maximum forward gain. The Yagi antenna offers many advantages over other types of antenna in many applications, yet both advantages and disadvantages need to be weighed up to ensure the correct type of antenna is chosen for any particular use.
The Yagi antenna is a very practical form of RF antenna design that is suited for applications where gain and directivity are needed. Although the cost is higher than more basic antennas, the Yagi often provides the most cost effective option for gain and directivity.
Typical Yagi Uda antenna used for television reception Yagi antenna development Although the Yagi antenna is now widely used, it was only in the late s and early s when it started to be used. Yagi antenna - the basics The Yagi antenna design has a dipole as the main radiating or driven element to which power is applied directly from a feeder. Basic concept of Yagi antenna The amplitude and phase of the current that is induced in the parasitic elements is dependent upon their length and the spacing between them and the dipole or driven element.
It is normally a half wave dipole or often a folded dipole. The Yagi antenna will generally only have one reflector. More complex, room-size installations include multiple spheres and additional players, and in a participatory variation, the audience can select spheres from a shelf to place them on the player. While the overall acoustic effect is similar from sphere to sphere as the speed of rotation remains constant, the sound produced by each is distinct, affected by the randomness of its movement.
Magnetic tape, an obsolete material in our world of digital files, embodies a sense of temporality inherent to any analog recording of sound: we see the physical movement in time that produces the sound, but the recording itself is subject to decay with each playback.
Yagi enacts a reverse archeology of this particular media art history. By constantly exposing this moment, the work endangers the very act of exhibiting what has been found: the continual playing of a sphere gradually erases its protective layer of acrylic lacquer, which in turn necessitates treatment after prolonged exposure.
This resonates with more contemporary postminimalist approaches that have complicated the history of Minimalism, in which the form and material of the object and the relationship to its surrounding space embodied the essence of a work.
Tickets Search. Then try to tune to your local repeaters, which will only be visible on the display when they are transmitting, which isn't necessarily all the time. Once I got up on the roof I remembered to tape the ends of the cut pieces of tape measure for safety.
I used the Heavens Above android app to look up and track satellites with downlinks operating in the 2m band and had a go at pointing the antenna while setting the frequency on the computer. It's hard to do both at the same time so I got some help. We didn't really get any results that first time out, so I borrowed a friend's nanoVNA to try to check and tune the standing wave ratio of my antenna. I first set it to sweep between and Mhz, then calibrated it using the included open, short, and load nubbins.
I tuned my antenna by adjusting the spacing between the driven elements and the shape of the hairpin wire.
We're going for as close to 1 as can be managed here. Back up to the roof to try again. The satellites I ended up being able to hear the best were NOAA weather satellites, which transmit an analog picture signal containing satellite images that can be decoded from the recorded audio file.
My best attempt so far only had a small area that wasn't static, but you can see with the map overlay and compared to the full satellite image I looked up online, I've got a partial result here. It's so cool that signal came from space!
I used noaa-apt software to decode the images. Thanks for reading! Question 9 months ago on Introduction. Good morning, I have built a couple of these. First problem is they are prone to flopping in a light breeze and useless in a strong wind. Do you have any ideas to strengthen the elements? Second problem is storage. I've been toying with the idea of using a larger pvc pipe with end caps.
Very nice write up on the tape measure beam. Answer 16 days ago. You could try using 2 layers of tape measure with the curves in opposite directions. That might make the arms rigid enough to take the breeze from either direction. You would need to construct some more little brackets to hold the ends together Or you could just try to position the antenna so the breeze is pushing the arms straight instead of curling them up--might be your easiest solution.
For an all weather design you could use angle-iron shaped pieces for the arms probably aluminum would make sense and use a big enough pipe to nest all the pieces inside for storage. Since I don't have a 3-d printer I'd just use pvc x fittings for brackets and attach the arms with a set screw. Or you could find 3 pieces of pipe that fit one inside the other.
Go with schedule 80 pvc conduit for extra toughness. Have fun! Answer 21 days ago. Answer 9 months ago. Reply 23 days ago. The elements flop around. If you can deal with that, you can store the antenna by wrapping the elements around until it looks like a stick, wrapping each with a tie wire, then putting it in a bag or bigger pipe.
If you can't deal with the rigidity problem, make antennas the old-fashioned way, with rigid tubing elements. Of course it needs a plane to store it against wall or ceiling but the hard part is transporting it.
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