Jupiter Radio Antenna tryout and receiver

[mswhin63 (Malcolm)]

Hi All,

For a while now i have been investigating Jupiter Radio and a good starting point into more advance radio astronomy. We don't have much here in WA other than ASKAP which is not accessible to the general public for hands on approach. Maybe one day for me

Anyway As I have a very tight restriction in my backyard I decided to create a Ring Antenna. I would say the worst of it was was the finch cage wire as I have limited finances I decided on this instead of bare metal flywire (which I can't find).

There is 2 final stages I have in mind for this antenna to complete.

• Install ALT/AZ motors to control the antenna. - Already the piano wire
• Redesign the antenna for 1/2 wavelength operation if possible.

This antenna is a compromise on design between a fixed 1/2 wave dipole antenna which is too long to be functional in my home and a Yagi (my preference) which is also too large for my home.

Simple construction using Capral Aluminium which joiners. Although plastic I have electrically and rigidly connected them with squares of aluminium.

Initial tests have been promising. 20 minutes of testing I was able to hear faint Jupiter L-Burst.

I had also made a Jupiter radio I purchased from Altronics - www.altronics.com.au I have not informed anyone on this forum because I owe thanks to ASWA to setting up the Radio Astronomy section to get me started. I have advised them that Altronics had only 5 unit left after which they will stop providing the kit. They have already deleted them off their wholesale so I cannot buy the remaining stock and I have given ASWA members plenty of time to purchase the receivers and if anyone is interested they can see if there is anymore left.

- http://www.altronics.com.au/index.as...=item&id=K1127

[lepton3 (Ivan)]

Malcolm,

Any links to reference info on dimensions etc?

I built one of those Jupiter receivers last year, but got poor results with an inadequate 1/2 wave dipole antenna because I do not have enough room in my back yard.

Your initial results sound promising, and it looks like it would be possible to install on the roof of my workshop!

-Ivan

[mswhin63 (Malcolm)]

Hi Ivan,

My dimensions are rough but the primary centre dimension of the centre square is 865mm. Essentially each aluminium tube is 840mm in length with Capral joiners which measure at 25mm. The outside shield is restricted only by preference but I made the outside shield extend to at approx 410mm. I am thinking I would have gone a bit further but knew it would fit in the garage if i extended it bit further.

In time I will try to itemise each joiner and some special connection I use so that I can quickly disassemble and reassemble.

This one factor I incorporated as I like to take the antenna with me to DSO evenings. Currently the main antenna need to be fixed to the roof but I don't have a roof rack (yet).

I will post more information as it comes to me.

[Visionoz (Bill)]

Hi Malcolm

I thought you were building a DDRR antenna - that mesh you're using is fine for a ground plane though the surface area might not be optimal for 20MHz - this one looks pretty well made!

Perhaps an antenna amp would be the go?

Cheers
Bill

[mswhin63 (Malcolm)]

A DDRR was too comlicated and in most not necessary. Also simplicity is a key to Jupiter radio.

Yes I would agree the signal level maybe a bit low compared to a dipole but am going to test it soon to determine roughly how low it is.

I am considering an antenna amplifier, may consider building one myself but need to determine how much gain will be too much. I suspect a maximum of 20db should be OK before too much noise is produced.

I quite possibly will make it a masthead amplifier not receiver amplifier. This should hopefully reduce the chance of noise increase.

[mswhin63 (Malcolm)]

Originally Posted by Visionoz

Hi Malcolm

I thought you were building a DDRR antenna - that mesh you're using is fine for a ground plane though the surface area might not be optimal for 20MHz - this one looks pretty well made!

Perhaps an antenna amp would be the go?

Cheers
Bill

Hi Bill just check my design handbook and the mesh is fine, it recommend metallic flywire type screening though as it only a reflector. There is a couple of design changes after reading the handbook.

Reduce the extension of the radiating element to about 200mm currently at 750mm - This should also help improve balance.

Second one is to extend the outer parameter but not by much. It only requires minimum 10% which it is quite close. The design though may not fit in my garage.

The design does suggest an antenna amplifier so I will give this a go as the next project. I prefer balanced injection. Unbalance is always dicey with hum.

[ballaratdragons (Ken)]

It's nice to see people interested in Radio Astronomy. Good thread Malcolm

I too am a bit of a Radio Astronomy enthusiast but have found that people tune out (no pun intended) whenever the subject is raised.

Our Clubsite will have a NASA Radio Jove setup in the very near future.
http://radiojove.gsfc.nasa.gov/

[mswhin63 (Malcolm)]

Originally Posted by ballaratdragons

It's nice to see people interested in Radio Astronomy. Good thread Malcolm

I too am a bit of a Radio Astronomy enthusiast but have found that people tune out (no pun intended) whenever the subject is raised.

Our Clubsite will have a NASA Radio Jove setup in the very near future.
http://radiojove.gsfc.nasa.gov/

That is cool, I knew there was a few people online interested. I may put it to the committee to place a Jupiter set-up at one of the DSO sites. Will try to configure it properly too.

The system runs on so little power that it could easily run off a small solar, left mine switched on 80AH battery 2 nights ago and forgot to switch it off. Still running this morning. The only issue would be IP connectivity.

BTW I managed to get some sound and visual from a dipole and incorporated images from a program call Spectrum Lab.

First sound file RAW - http://www.waelect.com.au/mswhin63ap...1_portion2.wav
Second file using artificial uncalibrated noise reduction - http://www.waelect.com.au/mswhin63ap...1_portion3.wav
Third file waterfall - http://www.waelect.com.au/mswhin63ap/sounds/capt00.jpg
Fourth file 3D - http://www.waelect.com.au/mswhin63ap/sounds/capt01.jpg

Nothing at the moment is calibrated.

[tempestwizz (Brian)]

Do you have any information regarding what frequency(ies) you are looking to detect? There are a couple of ways to improve the antenna type while keeping it compact. Also, the method of coupling the signal from the antenna can have a great affect on efficiency of collection.

If the frequencies are below 50 MHz, perhaps a magnetic loop antenna ( H-field) may prove very effective. These are physically quite small and very efficient for the lower HF frequencies. They are also relatively immune to urban E-field noise from power lines etc. The trade-off for this is they are very narrow bandwidth.
If the frequencies are higher, then a helical design is very attractive. These look a bit like a cork-screw and the centre pouts toward the target. The more turns in the cork-screw, the higher the gain and directivity of the antenna.
There's plenty of info available on these designs ( I think). Maybe worth considering. Any gain you get in your antenna is better than through using amplifiers, as the latter introduce additional noise.

HTH,
Brian C

[mswhin63 (Malcolm)]

Hi Brian,

I was going to treat Magnetic Loops with caution because have had some reports they lack sensitivity, but I am always open to suggestion. Firstly I was going to look at what could be done with this model and make improvements. One thing was a 15 to 20db masthead amplifier mention above then look at the proximity of the element to the reflector. I have been told there is about a 15db loss with this design so I will look at these first before a re-design into a new antenna.
Thanks for the suggestion though it is possible the narrow bandwidth may have been a factor in the past designs to give the bad reports.

I was hoping one day to try make all different types mostly to test personally efficiencies etc. Good practical experience before starting the real studies at Uni.

The construction design will be similar to any model I decide to make within limits.

[I.C.D (Ian)]

Nice clean shed ,How do you do it
Ian.C