X band Milsat and Deep Space Set-up

[satosk]

S band is my old friend and a colleague from other satellite boards, so I wanna share my know-how and help him or others.
All parts are a pro grade.

Last 2 pictures are of a professional prime focus feedhorn provided to us (me and Peon) by our friend DX Bozoth to who we send our big THANK YOU for his help and colaboration. We are both truly honored to know him in person.

 

[Channel Hopper]

I should have explained slightly better, the antenna 'leaves' would best sit at the focal point of the dish, with the cable running back to the same exit point as you have on the finished piping.

The dimensions of the clover aerial on Amazon do appear to be incorrect for 5.8GHz, I would have expected something smaller in the first place, but once trimmed to X-band frequencies would/should mean a maximum diameter of 18mm, meaning an - approximate - 9mm gap all round a 35mm piece of copper pipe.

Hmmm, the item(s) turned up this morning, I ordered from two different suppliers as usual to see if, or who might be the origin, and they both arrived in the same parcel .

Apart from not being three leaf, they are four, plus the outside diameter is in the region of 3cm give or take a mm, so these are tuned for about 4GHz at the most. The most annoying part though is they don't even have the 90 degree SMA part on the blunt end, so whoever is selling these has really cut corners to make a better profit.

Anyhow, I now have the items here, and will have a look at the possibility of modifying them to the correct resonant frequencies after I've done the final touches on the Ku band stuff that I believe to be a more economical entry point to X band, though there is another fly in the ointment.

A loss of a part, ordered via Amazon has been in stasis in the post (Royal Mail now admits it has 'gone missing' in their depot) which means the Chinese - once again - have to send another out in good faith, they have done, then claim as the sender on the compensation forms, recipient can't do it on their behalf.

Our country really is going to suffer as a result of the standards of the larger dinosaurs once trading has to be proven to be efficient.

 

[s-band]

I am not sure how this would work as a dish feed as the pattern is similar to that of a dipole. The cloverleaf would need to be on its side but there is a risk that there would be a lot of overspill. Cloverleaf Antennas.

The quickest way I found was to use plumbing with a squashed guide polariser and 1/4 wave probe feed. Luis' scalar calculator (in 1st post) is good for primes and plumbing reducers work for offsets. I am now using a GD/Prodelin feed for the offset dish. It has been bored out to take a 28mm tube. Although the scalar spacing is wrong it works reasonably well as it is better matched to the f/d of my dish.

I found W2IMU's work and derivatives most useful for offsets and de-polarisers w2imu - Google Search

 

[Channel Hopper]

I was going to use just the terminations of the product, desolder the cloverleaf that is current, then resolder a different design of 'probe' onto the end, for the price at the time (they have gone up by 25%) they looked to be the most economical way of constructing a feed, giving a degree of flexibility in setting the best point for the resonant parts.

The lack of 90 degree connector is annoying though.

 

[Channel Hopper]

Since I am a bit stuck awaiting components to arrive (I have already dismantled everything I might need, in readiness for the modifications) I've had a rummage through the shed and found exactly what I require mechanically.

Based on Luis recommended diameter for the 8.4GHz feed system and converting these to the 7.5GHz Milsat band by fraction, gives an internal diamter of 29.15mm.
The usual aerial mast used around here is the good old imperial size of 1 1/4", I have a offcuts of old and new aluminium in spades, and the first piece out of the shed has the internal diameter of 29.15mm, spot on !

Next I need to drill and tap the top section to enable fitting of the probe components inside.

The universal LNB I have for the project is fitted around a cast alloy chassis, this has an internal throat diameter of 16mm with the probes set at 90 degrees from each other via simple soldering direct to the PCB. I'm hesitant to modify any of the components already on the circuit board apart from those necessary to change the reception band so I will probably retain just one of the two probes since only one polarity is required for Milsat detection (LHCP).

If I do require RHCP then I'll turn the dielectric plate around.

 

[Channel Hopper]

I think I owe the second supplier of the 5.8GHz cloverleaf antenna an apology.

X band Milsat and Deep Space Set-up - SatsUK

Another package arrived this morning (From Cambodia, not China) and inside is a similar device, but with the 90 degree connector. All other dimensions are the same however, with the vanes at 30mm.

So, I now have three of these in the drawer though I only ordered two of them, perhaps the first sender is doing a BOGOF on substandard units ?