old school

[scudGB]

hi all
i have recently found L band after a article on rtl.sdr.com , i bought the patch antenna that was talked about and i am now hooked the problem i have is i need instructions on making a passive patch antenna the old fashioned way (words and plans) rather than something on youtube any pointers would be a great help as every search parameter for L band patch seems to end up with the same few sites and the same non detailed instructions thanks scud

 

[scudGB]

hi all
have been watching vids on you tube by these two guys 9A4QV and EA4LE they both have nearly the same sizes one uses a 98 mm sq the other 94 mm sq for the tuned element so i decided i would try a 95 mm sq tuned element
as i do not have the tools to cut sheet metal i bought a sheet of double sided pcb of ebay 200 x 300 mm as it can be cut with a heavy craft knife
after cutting a 95 mm strip of the long edge i was left with a 200 x 205 mm reflector ,cut off two corners at 21 mm in as both vids show
then mounted sma connector on reflector but had to extend centre pin with a random bit of wire as luck had it i had four pcb mounts to allow me
mount tuned element
as i was unsure of how double pcb would act i trimmed copper away from feed point on underside and only soldered front face to feed
tools used steel ruler /craft knife /cordless drill and soldering iron cost of pcb ,sma adapter and link £16 bet less for stateside
connected to airspy no extra amp AND IT WORKS !!
made a very poor vid as it was hard to hold ipad steady with one hand ,,a very happy scud

 

[SDRPlayer]

Well done Scud, i made the same antenna for my 1M dish with great results. No better feeling making something like this from scratch, connecting it and works!

 

[scudGB]

HI all just found this on you tube a far better " HOW TO " for a L band patch antenna ,scud

 

[scudGB]

hi all
follow up from patch antenna ,due to the fact we are running into winter uk and my location within uk i am now looking for a indoor antenna with enough gain to compensate for a path through my roof slates (real welsh slate) the patch i made now with amp can get a signal but not enough to
lock on 10500 (my target for next antenna) my options are limited the largest dish i could try would have to be a 90cm oval dish due to loft hatch or go for a helical the advantage of helical is i could go up to 1m tube lengh =about 22 turns est 17db gain but i have no clue on gain of dish using either a new path or small helical with correct polerisation for reflected signal ,so any input with pics please (SDR PLAYER ) or rest of world
cheers scud

 

[scudGB]

HI ALL
i am so disappointed got hold of a 1M X 64 mm tube and a roll of 3.2mm copper wire ,this resulted in a 20 turn helical did my best to match the first part of coil 1 then had a go results poor !!
the coil is almost the same as the patch antenna i made (vid) so i am giving up on helical for now as i am stumped without test gear will have a further go when the nanovna 2 hits the stores
learnt 1 lesson get soft drawn copper ! had a real job to bend my wire scud

 

[scudGB]

HI ALL
just made small vid of my home made patch antenna now with a basic nooelec pre amp fitted very happy with performance expecting a slightly better signal once the leaves are all off the trees not to long ass had a few frosty mornings all ready
next project is to make a fully waterproof set up and fix it on alphasat as a bit nearer to my location
one question do you think two patches could feed into one amp for a extra bit of signal ? scud

 

[spongella]

Interesting project scudGB. Made this one a while back, a helical patch. But I used it with a satellite dish, worked well but I could not get the free decoding software to work so I gave up. Was fun to build though. Building an L-band helical antenna for Inmarsat

Nooelec has come out with an L band patch antenna recently. What decoding software do you use? I do remember there's one that works but you have to pay for it.

 

[scudGB]

hi spongella
using all free software for all the aircraft stuff i use jaero from...http://jontio.zapto.org/hda1/jaero.html realy good site lot to read
and a youtuber "signals everywhere" has 3 vids that will show you how to set up if you want to listen to 8400 audio
and for the marine i use scytale C also free and is now a plugin for SDR#
if you do not want to listen to aero audio there is a windows .exe on jonti web site
the hardest part may be setting up "virtual audio cable" that they both need scud

 

[hamradionl]

600 + 1200 baud VBcable will do nice jobe but for 8400 + 10500 iam not able to get those 100% working not get 3x green LEDS.
Why JAERO not use INPUT from localhost

 

[scudGB]

hi hamradionl
not sure on your exact problem but if you watch both my vids you will see on the first vid i was unable to get a lock on 10500 signal
but just about managed to keep locked with my patch antenna and lna as vid 2 the . signal strength shown when i was on 10500 is probably
the minimum you will need ,as for 8400 probably same signal strength as 10500 but you also need the audio codec to hear audio
are you in holland with the nl on your name ? and what sat are you looking at alphasat best for you if in europe
as for jaero inputs no idea i just use vb cable and all works ok

 

[hamradionl]

I see 2 sats signals, above atlantic and best signal i get from AlphaSat but still need better signal
I live in heavy city area, buildings and using the patch antenna for the 600, 1200 is not a problem but from 8400 and 10500 in VBcable i notice lots of pull and push drops and JAERO messages CRC error and audio buffer under run. In the past using VBcable see the same problems using AX25, DSDplus, tetra or any other higspeed data.
What i try:
1e - over the patch antenne i made a horn or cone about 10 - 20 cm long and that give some signal improvent
2e - from a extra metal plate on the back from the patch antenna and distance is very critical move it back and fore to find the exact distance from backside, that give also better signal. (actually on the back side are 2x metal plates, i will try made the back one little bigger)
Use a old cooker top or any other metal plate, just for try it out you will see the signal go up only at particular distance from the back side
SDR# only use the patch antenna the signal SNR = 7 with these 2 modifications the SNR go up to 11 - 14.
For 8400 and 10500 now is better and my next step is get the signal go up somewhere between 15 - 20

 

[hamradionl]

actually on the back are 2x metal plates, later this week i will try made the 2e back plate a little bigger

 

[scudGB]

hi hamradionl
put some pics of your work when you get sorted please ,scud

 

[scudGB]

UPDATE ON HELICAL
hi all had a further go at helical antenna found a strange thing if i point at alphasat using bearings from dish pointer results are poor but if i set up the old way just keep moving around for best signal a bit better ,,its hard to tell from pic but helical should be looking way higher than alphasat
can only assume helical has r reception pattern like a douhnut ?? not sure why but it now works enough to lock on 8400 signals ,scud

 

[hamradionl]

This weekend start working using the patch in front like LNB, those small TV dish antenna. This give a massive improvement specialy for the 8400 + 10500.

 

[Remon]

I see different designs from the L-band patch antenna.

1. With nylon spacers between reflector and radiator.
2. With the reflector shortened to the radiator in the center.

Which one should I choose when building this antenna?

 

[scudGB]

HI Remon
1 nylon spacers are easy to make i just used nylon nuts and bolts with nylon washers to build the 7mm gap ,,,7 mm seems important
2 some people short the reflector to prevent static buld up killing the sdr front end ,but as i live in damp old UK do not expect a lot of dry air here
as you can see in vids its more a case of do the best you can with what parts you can get i got all my parts of ebay uk and tools used ..good craft knife, saftey cutting ruler,soldering iron and cordless drill alas no vna yet scud