The calculation and gain graphs are made with the antenna oriented with metal grounding on bottom (towards Earth). Inverting position, affects those graphs.
Regarding “lightning suppression”, pretty much my understanding of whjat is happening and how they work, is that in the moments before a strike occurs, there’s a really high potential field across a very wide area, and anything sharp (even non-metallic stuff feels this) starts to act as a point discharge generator; the lightning suppressors allow the voltages “felt” by the antenna to dissipate easily to ground, reducing the local voltage gradient at the antenna. This should make it less likely for a leader stroke to be able to form from the antenna or associated cabling, and will as a result reduce the damage seen when there’s a nearby strike. Hopefully the location of the antenna and the local lightning protection will work to prevent a really close strike from creating really strong local potential fields and then preventing strong leaders from forming.
Direct strikes are generally death to the under-protected equipment. I’m involved in ham radio and I’m learning about the how-to stuff for lightning damage minimisation techniques, and I am amazed at the absolute power in lightning. Voltage spike rates fast enough that a slight bend in a cable starts to act as a portion of an induction coil, delaying the transmission of that voltage spike a bit until it’s even steeper and faster once it passes that point, and spark gaps being your friend to remove most then some then to cut down the spike enough before it gets to the amplifiers and radios . Really interesting techniques.
But, getting back on topic (and apologies!), if it’s possible to put well-designed lightning rods around the antenna (maybe 3-5m tall and 3-5 metres away) it shouldn’t affect the reception, but should make a direct strike much more unlikely, and the suppressors would then be able to handle the resultant electric field much more easily.
2 Likes
Yes, you are right.
My central Michigan setup.
Older Raspberry Pi 4 - 1gb running PiAware 6.1. With FlightAware blue and Orange dongles. A cable Matters HDMI to VGA adapter. Plan on adding a 5" touch screen this summer. The 2N2222 switching transistor off to the left starts/stops the fans on the P4+LP1007F heatsink case (via a temperature script). Hi temp level set at 48C then turns off when reaching 40C. Doesn’t really run that often. Just starting to test PiAware 7.2.
I feed FlightAware, ADSBXchange, RadarBox,FR24 and Flight Tracker.
Tower top is 37 feet with 1 - 6 & A/B mounted above that and three wire antennas #7, #8, and #9. Open sky from 75 to 280 degrees. Neighbor’s trees to the north. Feed lines are LMR400 (about 60 feet) to my basement shack.
- Wide band discone @47’
- 800 mhz beam for Michigan APCO-25 network receivers @42’.
- Airband J-pole @39’ feeds into Stridesberg amp then to Stridesberg splitter
- 987 ADSB antenna @39’
- 146/440 meter J Pole @39’
- 1090 ADSB antenna @39’
- Multiband Shortwave North/South @33’
- Multiband Shortwave East/West @33’
- 135’ Long-wire running East/West @25’
A & B are small OTA TV antennas @38’
I want to test a tower mounted receiver setup this summer to see how signals may improve.
7 Likes
Love it.
73.
2 Likes
I’d rather put a phased antenna array on top of those towers and take my chances with the lightning! 
2 Likes
Pretty similar to mine 
What you can do optional is using a short USB extension cable between Raspberry and the Airspy stick. This reduces the heat moving from the Airspy to the Raspberry USB slot.
I was not able to identify any performance disadvantage, only using the Airspy at 20MHz (which is outside the official specs) can fail.
Just an option, no must have…
2 Likes
I put flexible connections between all my boxes. This way no mechanical stresses are transferred.
And of course, no heat either.
5 Likes
So the homemade spider got swapped out today and the antenna is now on a 12ft pole that’s 9ft clear of the roof with 7.5m of LMR200 cable.
So have gone from this
To this (red line is the height spider antenna was at before the change)
7 Likes
Hi there,
I’ve reworked my setup following a failure, it is (to me) a bit cleaner, and assembled another transistor board to control the fan.
That’s an outdoor setup, powered over Ethernet, with a flat cable running through a window.
Board is (still) that good old OrangePi Zero, FA PSP stick + filter, 1,5 or 2m of RG-58 to harness the antenna.
Regards,
Guillaume.
1 Like
A coax cable could not go trough that window?
They make flat coax jumpers to pass through windows.
1 Like
I have two of them here and both showed a significant drop of messages, mainly while Window is closed.
Once i open it up, the numbers are back.
I would assume there is still something in the window frame (e.g. metal) which prevents proper data flows.
No, it is too tight.
But that’s not an issue either, as it all started from a “case study”, “what does it take to put a receiver outdoor?”.
It evolved over years, the fan is almost optional here with a careful power profile setting. There’s someone in Oz who took a different approach (Ruggedised Orange Pi Zero - lucsmall.com) whereas PoE has always been a requisite for me.
That’s the flat cable I use: Samzhe Cat6 Flat Ethernet Cable 1000mbps 250mhz Cat 6 Rj45 Networking Patch Cord Lan For Computer Router Laptop - Ethernet Cables - AliExpress
so nothing special, with a PoE switch at the other end. It also allows me to use a “fully wired” interface and spare the use of the (unreliable) wifi interface of this board.
IMO putting the receiver and Pi outdoors, especially in warm climates, is not optimal.
Reasons: Temperature management, fans failures, EMF noise pollution by Pi located in proximity of the antenna, and increased thermal noise at RF end. Also lightning/electrostatic protection of the Pi is zero at that location.
A filtered LNB at the antenna and a T power injector, plus a gas surge suppressor, located in the house are better in all those respects.
I had my Raspberry 4B outdoor during last winter and summer, no issues at all.
During winter times i disabled the fans of the Armor case.
The device was in a wooden box with air holes to get it floating, these were also covered during winter.
Summer operational temperature of SoC never went over 60°C, so there was plenty of room in case the fans failed. Disabling them changed the temp by around 10°
Now the Airsquitter is outdoor. Jetvision announced the usage in an environment of -20 to +60°C
I think the major issue could be humidity.
I run a script every three minutes to check the CPU temperature, turn the fan on if over 80°C, forces on for 10 minutes. At next check, if temperature is below 75°C, the fan is turned off.
I’m currently running the CPU between 480 and 960MHz on the “ondemand” power profile, but proior to that I was on the “conservative” profile and it almost never kicked in.
1 Like
Definitely that’s a major factor. But also running cooler can yield better performance because lower noise.
Here this morning humidity was 71% RH, now is only 56%, but temperature increased to 31° (feels like 38°).
1 Like