Hello everybody!
I would have just one question about loop antenna.
I have recently found out about two "radios" if I can name like this which are based on some types of antenna like: loop, bi-directional, dipole and, connected to some modules you can tune-in even as remote, them being mounted in different countries and by remote tunning you can tune-in long waves, medium waves, short waves and SSB and you can receive different stations from the different servers during day or night or depending by distance. I could also tune amateur band 3705KHz romanian.
Here are the adresses:
http://websdr.ewi.utwente.nl:8901/
and:
Wideband shortwave radio receiver map
at the last one beeing a map and can be chosen which area you want.
It's interesting that from a source like Hungary I can tune into a west romanian station on 630KHz and also BBC on 198KHz. Is there a way if I would replace the ferrite rod from a radio with a cable or with a loop antenna and I would place it on the block of flats where I live of 8 floors to receive more stations on both long and medium waves during day and night?
Thank you very much!
I would have just one question about loop antenna.
I have recently found out about two "radios" if I can name like this which are based on some types of antenna like: loop, bi-directional, dipole and, connected to some modules you can tune-in even as remote, them being mounted in different countries and by remote tunning you can tune-in long waves, medium waves, short waves and SSB and you can receive different stations from the different servers during day or night or depending by distance. I could also tune amateur band 3705KHz romanian.
Here are the adresses:
http://websdr.ewi.utwente.nl:8901/
and:
Wideband shortwave radio receiver map
at the last one beeing a map and can be chosen which area you want.
It's interesting that from a source like Hungary I can tune into a west romanian station on 630KHz and also BBC on 198KHz. Is there a way if I would replace the ferrite rod from a radio with a cable or with a loop antenna and I would place it on the block of flats where I live of 8 floors to receive more stations on both long and medium waves during day and night?
Thank you very much!
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You can either try a (next to) quarter wavelength piece of wire or you could go with the more sophistcated receiving antenna which the university of twente sdr also has in place. It's the mini whip antenna originally designed by PA0RDT. A quick google search did turn up this link: PA0RDT Mini Whip - you might find more (and even ready made ones) by searching for mini whip antenna. this on has the advantage of being active, short and having a very wideband useability.
PS: 73 de DG6RCN 🙂
PS: 73 de DG6RCN 🙂
The first idea for this type of antenna was published by E. Nordholt, my electronics teacher at Delft university:
A new approach to active antenna design,
IEEE Transactions on Antennas and Propagation ( Volume: 28 , Issue: 6 , November 1980)
A new approach to active antenna design,
IEEE Transactions on Antennas and Propagation ( Volume: 28 , Issue: 6 , November 1980)
In all the communications receivers I own(ed ) I always used an end fed aerial (antenna ) this was coupled to a ATU I made myself out of two old --air spaced radio variable capacitors and a very large self wound tapped coil with a switch ( ceramic ) connected to each tapping .
This made a vast difference to the signal reception even with highly sensitive 2RF stages- separate FC & Oscillator- 4 IF stages - NR-BFO/SSB - 2 stages of AF input and push-pull output--etc -etc .
Use ceramic insulators for low loss as well as good satellite quality down-leads.
Long Wire: End Fed Wire Antenna » Electronics Notes
This made a vast difference to the signal reception even with highly sensitive 2RF stages- separate FC & Oscillator- 4 IF stages - NR-BFO/SSB - 2 stages of AF input and push-pull output--etc -etc .
Use ceramic insulators for low loss as well as good satellite quality down-leads.
Long Wire: End Fed Wire Antenna » Electronics Notes
The problem is this: now I'm living on a block of flats at 1st floor from those 8. The idea is that the building is somehow shielded and the reception. Could be good on MW, LW and SW if I move the radio either to the kitchen or in the balcon other wise no chance. On the FM things are worse. Hardly I can find a good position for most of the station to be tuned at a high or good level without having the 'moving problem' through the room, that kind of influence. The noise I tried at least on MW and LW for an inkel tuner to eliminate while connecting a cable to the heaters pipe but the reception I would like to be the best. Previously when living with my parents at another block of flats at 5/5 floor I didn't have this problem, but the building seems to be made by other materials and even with short antenna made by me a simple dipole it could work. The same problem happens now with a valve radio on FM because it also has dipole antenna.
My city sits on several hills, so now the block where i live is on a hill. This was the reason of having some ideas such this about making some changes for a greater reception: a new antenna on top of the block.
My city sits on several hills, so now the block where i live is on a hill. This was the reason of having some ideas such this about making some changes for a greater reception: a new antenna on top of the block.
by FM i guess you mean th FM radio broadcast band at ~100MHz? for that I would definitely use a dipole antenna on top of the roof.
For longer wavelengths I'd still go active if I can, because then no tuning is required. The wire antenna with an antenna tuner is another option of course and can be very efficient. A tuner would be required but it could be very small for receiving only.
Btw I also had good results with this concept, using a half wave antenna on 2m, end-fed with a tuner in a small enclosure with a connector to handheld radios on 2m. It's far superior to quarter wave because it's high impedance and thus not requiring a good HF earth (your hand isn't one 🙂 )
For longer wavelengths I'd still go active if I can, because then no tuning is required. The wire antenna with an antenna tuner is another option of course and can be very efficient. A tuner would be required but it could be very small for receiving only.
Btw I also had good results with this concept, using a half wave antenna on 2m, end-fed with a tuner in a small enclosure with a connector to handheld radios on 2m. It's far superior to quarter wave because it's high impedance and thus not requiring a good HF earth (your hand isn't one 🙂 )
No amount of amplification on a short aerial is going to compensate for a very weak and noisy signal especially if you say----"I live on the first floor of an eight story building which appears to have some sort of RF shielding built into it ".
What I posted in post #4 applies here , if its a flat roof install a wire dipole for the FM or an FM directional aerial and an end fed aerial for LW/MW/SW with an ATU attached .
This works I have fitted them in every property I have lived in or owned.
What I posted in post #4 applies here , if its a flat roof install a wire dipole for the FM or an FM directional aerial and an end fed aerial for LW/MW/SW with an ATU attached .
This works I have fitted them in every property I have lived in or owned.
Hello!
Yes, duncan2, the so-called roof is flat. In fact is just the block terrace, clear and flat.
While reading on the internet, I also found out some possibilities to improve the reception. These should be:
http://dl1dbc.net/SAQ/Mwhip/Article_pa0rdt-Mini-Whip_English.pdf
Medium Wave Active Antenna
RADIO-TIMETRAVELLER: The Twin Coil Antenna Patent
How does each work and which one should be better?
Yes, duncan2, the so-called roof is flat. In fact is just the block terrace, clear and flat.
While reading on the internet, I also found out some possibilities to improve the reception. These should be:
http://dl1dbc.net/SAQ/Mwhip/Article_pa0rdt-Mini-Whip_English.pdf
Medium Wave Active Antenna
RADIO-TIMETRAVELLER: The Twin Coil Antenna Patent
How does each work and which one should be better?
The first two mainly pick up electric fields. They compensate for their "shortness" in relation to the wavelength by doing an active impedance matching using a very high input impedanve fet amplifier.
The thrid one mainly picks up the magentic field portion. it's somewhat directional like a dipole and seems to be tuneable to the desired RX frequency.
The thrid one mainly picks up the magentic field portion. it's somewhat directional like a dipole and seems to be tuneable to the desired RX frequency.
One mor thing: depending on how much HF interference you have around your antenna, a tuned antenna might be preferrably in "dirty" environments, as the tuner also acts as a preselector somewhat filtering interference in other bands.
Ok but about the diagram of Medium Wave Active Antenna, why we should need the varicaps? For a precisely reject of adiacent frequencies or for a better reception? If I don't have the varicaps, can I replace them with a dual section 2x365pF or 2x430pF capacitor? I have small inductances of 330uF which seems like resistors. They are suitable for this?
as you will want to install the active antenna on top of your roof its probably best to go with these variable capacity diodes, you gain remote control... otherwise you'd need to have a motor drive for the variable caps. would have to look at the datasheet if your variable caps are suitable. You could also plug in your caps and the inductor value into the LC tank circuit formula and find out the tuning range... ( LC circuit - Wikipedia )
The inductor you mentioned is probably useable, but once again you'd have to look at the datasheet of it to find out in detail.
The inductor you mentioned is probably useable, but once again you'd have to look at the datasheet of it to find out in detail.