How to build your own Frame-Antenna!
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- เผยแพร่เมื่อ 14 มี.ค. 2017
- This is the "video build-manual" for our frame-antenna kit.
Support Roger on Patreon: / kainkalabs
You can also build your own parts via the open-source svg-files:
www.kainkalabs.com/upload/ind...
Description of the properties of the frame-antenne here:
• New Frame Antenna avai...
Shop-site: www.ak-modul-bus.de/stat/radio... - วิทยาศาสตร์และเทคโนโลยี
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thank you very much for your vidéos about radio
i loved your Slow/Wise/Easy to understand English , beside the detailed illustration for every thing and the reason To Use it and it's Feature ... Thank You
Thanks for the video. Being home with Covid and entering the DX season in the Northeast, USA, I'm going to give this a try! I'll check back in with my results.
Your thoroughness is laudable. The videos are excellent.
Roger, thank you for another wonderful video!!
It works, It works, thank you so much, It works.
Nice work
Very informative
I built my own 1 inch PVC pipe 2 foot (61 cm) square passive LW-AM frame antenna out of PVC pipe with 42 turns of regular single strand enameled copper 22 gauge wire with 365 pf variable capacitor tuned for 150 khz to 1710 khz tapped with 2 switches for LW, MW low and MW high it works very good as is with bi directionality with my radio placed next to it I have been thinking about replacing the present single wire coil with litz wire in hopes of improving the sensitivity even further.
Nice work! But what is 22 gauge wire (for a European who lives with the metric system)?
In doing the calculations for my frame-antenna concerning minimal skin effect and proximity effect, I found 2 optimal solutions: A single strand (solid) copper-wire of 1...1.5mm diameter or litz-wire with 90x0.1mm. The turn should hve a separation of 6mm (or more). That way the Q-factor was higher than 200 for AM medium-wave!
For long-wave you don´t want such a high Q-factor because it already limits the bandwidth of the audio-signal!
A Q-factor of 50 results in a badnwidt of only 3 kHz at 150 kHz and that results in 1.5 kHz audio-bandwidth.
I'm surprised you didn't cut every other notch deeper and shallower to reduce capacitance in the loop itself. I've found the basket weave effect caused by the alternating notch depths quite effective.
That is in fact a further point for optimizing magnetic antennas, but...
The distance of the wire in each single is already calculated to give negligible external proximity-effect compared to the internal proximity effect of the single strands of the litz-wire. Perhaps you watch my video-series about the spreadsheet for caluclating magnetic antennas. There I demonstrate that the dimensions, layout and selection of the used litz-wire is optimized.
I guarantee you, that this frame antenna is much more sensitive and has a much better Q-factor (for MW-reception) than any other magnetic antenna I discussed in my channel. I had at first use immediate reception of AM-stations in more than 300 km distance with a crystal-radio.
This has to be the most tedious antenna, I hope it works well after all that effort. Did you consider a tuneable inductor, may be an active device ? We used a similar technique to hide antennas inside wooden picture frames. Surely this is Art.
It works extremely well :-)
We immediately had DX crystal-radio reception which is very difficult now that all AM transmitters are shut down here in Germany.
A lot of thinking and calculations with my self-created spreadsheet for magnetic antennas went into it, so that it gives the highest possible "true" Q-factor in combination with (in my opinion) good proportions and a good looking device.
1:35 I am new to this, just learned about the miracle of Litz wire for BC/SW antenna applications, and now I hear you say that solid core wire gives better Q-factor on this frame. Why is that?
Above 1 MHz the skin-effect which the useage of litz-wire wants to counteract) is outweighed by the (internal) proximity effect between the single strands of the litz-wire. So the AM frequency-range from 550-1700 kHz is just at the transition region.
From thereon the only remedy is to use a (thicker and thicker with increasing frequency) single wire or hollow copper tubing. At SW-frequencies of e.g. 10 MHz you need e.g. copper tubing of at least 10mm diameter for a high Q-factor.
Take a look into an FM-tuner or a SW-receiver and you will find coils only made out of thick solid copper wire and not a single litz-wire winding or coil-
Hi, tolles Video. Braucht das Ding eigentlich keine Koppelspule?
LG
Nick
Ist gedacht direkt als Schwingkreisspule und dann hochohmige Abnahme des Signals. Koppelspule kann man einfach eine Windung irgendwo daneben oder innen platzieren. Macht aber meist die Güte kaputt.
Hello, please a question, if I put a tap on the coil to reduce the inductance ... could I use the antenna for SW?
Short answer: No
cool
What band or range is this intended for? What are the results?
If you expand the video-description you will find the link to the video where I introduced our frame-antenna and explained the properties: th-cam.com/video/YEPW2ShFsqA/w-d-xo.html
It´s (only) useful for AM-radio frequencies (LW and MW).
I immediately hat passive crystal-radio reception of 3 different AM-stations all more than 200 km away.
(In Germany all AM-stations are shut-down. So the nearest was BBC in England.)
46:50 suppose I am using this style of antenna design with a homemade crystal radio that inductively couples the antenna to the demodulation circuit via primary & secondary windings on a common cylinder. In that case, when choosing the range of my tuning capacitor, I think I should be concerned with the total inductance of antenna+primary, and not just antenna. Is that correct? (EDIT: My question is a little off-topic, but this video made me think of this question.)
Why use a coupling winding? I have connected this directly to a 500pF variable capacitor and that goes directly to the demodulating diode.
What you have to watch out for is that four things have the same impedance to get a working crystal radio (explained further below).
Only that way do you get the maximum energy out of the tank circuit and the highest voltage.
Highest voltage is necessary because every semmiconductor rectifies only above the so called "temperature voltage" of 25mV at room temperature. Below that voltage there is no rectification but then the diode behaves like a resistor and conducts in both ways (forward and reverse biased). So you need at least 25mV of received voltage from the tank-circuit under load.
This is based on fundamental (quantum) physics and could only be altered by cooling the diode down to sub-zero temperatures.
And the "load" is the (dynamic) resistance of the diode and then the impedance of the headphones.
So the "Resonance Resistance" of the frame antenna (with a high Q-factor this is the range of about 1 Megohm in the AM frequency band) should be equal to the dynamic resistance of the diode and then the impedance/resistance of the headphones.
Because no headphones are available with an impedance of around a Megohm (or at least several hundred kOhms) you need a little transformer. The best you can get are secondhand headphones with 2x2kOhm. If you put the 2 capsules in series you already have 4 kOhms. Then you need a little audio-transformer with a 1:250 voltage ratio. Then the impedance of the headphones is transformed upwards to 1 Megohms. And then you still need a little 1 Megohm-Trimmer going to ground from the primary side of the transformer. That´s because behind the diode you have a DC-voltage + AC-voltage (demodulated signal).And for the DC-Voltage the frame-antenna also has to "see" only around 1 Megohm. That is accomplished by the 1 Megohm trimmer. Otherwise the tank-circuit would "see" only the DC-resistance of the transformer and that is only a few kOhms at best.
Beware of Germanium diodes! They have much too high reverse currents and much too low dynamic impedance (a few kOhms).
What you need are Schottky-diodes which have much lower reverse currents and much higher dynamic impedance than Germanium diodes. Of course we have a special HP Schottky-diode in our shop that has a dynamic resistance of several hundred kOhms for that purpose :-)
I am planning a video-series ("Mythbusting Crystal Radio Sets) for 1 or 2 years now to explain all these things in detail, but couldn´t find the time yet. Perhaps in one or two or three months.
The manual in German for our "Super Crystal Set" is already 3/4 finished. You can download it from our shop and try to extract the text and use Google Translate: www.ak-modul-bus.de/stat/detektorempfaenger1_crystal_radio_set1.html
And of course we have 1:50 and 1:200 audio-transformers in our shop exactly for that purpose :-)
@@KainkaLabs I completely believe you that your antenna would work just directly connected to capacitor & diode. Right now I am reading many blogs & watching many channels, and several of them have suggested (my rewording) that the resistance of the antenna/ground system will harm the selectivity of the tuning, and so it allegedly helps to have only a magnetic coupling between the antenna & the tuner.
I was 50% doubtful, because surely there would be voltage losses due to the coupling, with no guarantees that the outcome would be better than just living with the claimed voltage drop of the antenna. But: (1) the people that made this claim each had decades of experience with amateur radio, and (2) I am 2 days into being interested in this, so I didn't know what to believe.
Thank you for the informative reply. Your advice about impedance matching rings (haha!) true for me. But at the same time, your advice of Schottky vs Germanium seems to run counter to what I've read so far, for crystal radios. (I think potted Galena was essentially Shottky in behavior? But it seems like a few decades later, once Germanium diodes were available, everyone preferred them for their low forward voltage drop.
I have so much to learn. I would *definitely* watch your mythbusting series! Do you have a Patreon?
Patreon is at www.patreon.com/kainkalabs
That´s why the video-series will be called "Mythbusting...". There is so much nonsense out there which comes from the days when a) there were only Germanium-diodes with there low impedance and high reverse currents available and b) there were no small audio-transformers because ferrite-material was not yet invented. So you only had your 2x2k=4kOhm headphones which matched the low dynamic resistance of the Germanium diodes rather good. But therefore you had the problem that when loading your tank-circuit with a 4k impedance you lost all your sensitivity and selectivity. Therefore you mandatorily had to use a coupling winding (essentially a transformer) with a voltage ratio of about 1:200 to match the 4kOhm impedance to the 100k...1Megohm impedance of the tank circuit.
Now you might say: "Why does it matter at which position the transformer (coupling winding or audio-transformer) sits?".
But...by down-transforming the tank-circuit voltage with the coupling-winding you lose a lot of stations because now they are no longer above the 25mV threshold necessary for the diode to rectify/demodulate!!!
And that´s why they are all (well most of them) are wrong because they copy the information gained 100 years ago with the then available diodes and headphones (and no cheap, small audio transformers) and don´t use their brain to analyze the problem down to the ground.
I can guarantee you that the real experts in the field who are winning the contests in crystal-radio reception all have the same design-procedure as I have explained. One of the gurus in that field (Berthold Bosch) has received nearly 200 (!) stations with his extremely advanced crystal radio set! See here: www.radiomuseum.org/forum/detektor_fernempfaenger_preisgekroente_bauanleitung.html
And yes: the first "Crystal-Diodes" were in fact Schottky-diodes due to the metal-"semiconductor"-contact. But the "semiconductor" here (PbS, FeS etc.) was only by chance impurities "doped" as a p-conducting or n-conducting semiconductor. That´s why you had to search on the crystal for a spot with halfway decent rectifying action. With the invention of the Germanium-diode (or earlier with a vacuum-tube as a rectifying diode) the original "Crystal-Diodes" immediatley died out except for people who could not afford a tube-radio (or people who like to fiddle around with bad equipment for hours)
@@KainkaLabs I am glad I found your channel. What you said about the first "Crystal-Diodes" and chance dopings matches my assumptions. (And I recently learned that the schematic symbol for a diode is essentially a tribute to the crystal+catwhisker heritage.)
Really? I thought it was just an arrow in the (technical) direction of current-flow and a bar for showing the reverse polarity blocking of current. But the crystal+catwhisker tribute could be an explanation as well. Interesting :-)
is it possible to calculate for other frequency? i want to make a similar antenna for 80,40 and 20meter frequency. i searched, but i haven't found a good calculator online.
Of course it is possible. I have a short video-series about a spreadsheet for calculating magnetic antennas. With that excel-file you can calculate nearly any kind of magnetic antennas.
@@KainkaLabs i am specially looking at frame antenna, is this is same calculation and result for both Frame and Magnetic? i am not English, but if i understand correctly magnetic antenna use a smaller loop of wire to provide the coupling into the radio.
Do you add-in a variable capacitor to this loop for tuning loop to different freqs.?
Yes. The inductance of this loop is primarily intended for a 500 pF varabale capacitor to tune the AM frequency band and with the added 2,2mH inductor also the long-wave range at the other banana socket.
Nevertheless a loop-antenna can also be used differently in so-called short-circuit mode (without capacitor in parallel).
Then there is no resonance and it receives all frequencies equally.
@@KainkaLabs Interesting Thanks for info
I want to purchase the pre made kit but everything is in German - is there an American English link to purchase things?
You can use use the online-translation of your browser to see a translated version of the shop-pages. Nevertheless you only have to click "in den Warenkorb" on the product page:
www.ak-modul-bus.de/stat/bausatz_rahmenantenne_500_mm_fuer_mw_und,pd730!0,,FRAME-ANTENNA1-BS.html
Then you can click the Union-Jack icon "Cart" on the top right corner of the page to get to the checkout process, which is completely inEnglish.
If that is too complicated, you can als order by email to info@ak-modul-bus.de
Let's say if I want to design an antenna for 700kHz reception. What should I do first? Determine the dimension or?
The dimension is your "free parameter". Make is as large as possible or maneagable for you. Together with the value of your choice of a variable (or fixed) capacitor you get the necessary inductance. Then together with a suitable mutual distance of the turns you get the necessary number of turns to reach the calculated inductance. The choice of the type of litz-wire (number of wires and diameter of the single wires) is an experimental optimization procedure. For all these calculations I created the spreadsheet to get a quick and halfway reliable overview of the values to play around with.
@@KainkaLabs thanks sir!
By the means experimental procedure, do you mean I have to try my antenna like each turn what is the resonance frequency. If it's not correct I change the amount of turn until I got the correct frequency. Is it like that, sir?
I am sorry for my bad english
First you should download the spreadsheet I created. Look for the video-serie "A Spreadsheet for Magnetic Antennas" on my channel. There you will find the download link. Wih "experimental" I meant you have to play around with the spreadsheet to get an optimum compromise with available litz-wire types.
this antenna can use 0n SW range ?
No. The explanation is in my video-series "A Spreadsheet for Magnetic Antennas"
Hello,
This note has been written with Google Translator, sorry for the errors.
Please, can you activate "subtitling videos"?
You currently have it disabled and people who do not know English cannot enjoy your videos 100%.
Thanks and regards!!!
How are the SWR:s for TX?
This frame-antenna is only intended for reception! Antennas for transmitting in the LW and MW-band are completely different.
1:34 solid copper wire of 1 mm dia has more Q factor than 90 X 0.1 litz wire ????
Yes. There is a kind of transition-frequency even for the best litz-wires at around 1 MHz which is straight in the middle of the (medium-wave) AM-band.
At still higher frequencies (short-wave bands) litz-wire is completely unusable.
The reason is the (inner) "Proximity-Effect" between the single wires of the litz-wire which overwhelms the skin-effect at frequencies above 1 MHz.
I have made separate videos about skin-effect and proximity-effect.
Search for them in the playlist about AM magnetic antennas and about the spreadsheet for AM magnetic antennas.
With the spreadsheet you can see for yourself that at 1 MHz the solid 1mm copper-wire starts to achieve higher Q-factors than litz-wire.
@@KainkaLabs Thank you so much, very informative.
Hallo,the video is super but can you make this in the future in two languages because the german amateures need this mostly in german.Sollte doch gehen ...
That was my original intention and what the German TH-cam channel is intended for.
But you don´t know how much (unpaid) time and effort it is to produce these videos.
But you can help by adding German subtitles ("CC"=closed captions-)
No variable capacitor?
This video is about building the frame *_antenna_*. A variable capacitor is part of the LC tank-circuit, not of the antenna in itself. Of course we do have the fitting variable capacitors in our shop.
+1 but the choke instead of appropriate LW winding - it is no good
A dedicated LW winding doesn´t fit onto this frame any more because of the many more needed turns.
So better an inductor to increase the inductance for LW-reception than none LW-reception at all :-)
In this case - yes, sure.
Litzwire??
90x0,1mm
200+ American dollars for a kit with no amplifier?? And I have to build it myself? Yikes!
No.For the kit it´s 130 Euros incl. VAT = 110 Euros net = 130 US$
For the assembled antenna it´s 180 Euros incl. VAT = 150 Euros net = 175 US$ (which already includes 40 US$ of extra shipping costs)!
...and we don´t have even a 50% margin in it :-)
...and I haven´t found a commercial AM-Antenna with better reception quality (signal strength x Q-factor) anywhere in the world.
With the very first prototype model I managed to get crystal-radio reception of stations more than 200km away!
Many users have confirmed that this antenna enabled them to receive AM-stations extremely far away they couldn´t pick up with any other antenna they tried before.
...and you are of course free to build your own one with the design-files which are open-source and can be downloaded for free from our web-site.
So what more can we do?
Dont buy it, just copy it
@@KainkaLabs some people just have no idea
Nice!!!( way too long!!!)
Shot in real time nad nearly no cuts/editing. Therefore the length :-)