Diamond MAT50 | HamRadio 

Thank you for the added data. May I ask, do you believe that a larger magnetic mat would work better or more efficiently? My first thought when I saw the MAT-50 was the magnetic company signs for vehicles, approximately 3 to 4 times the size of the MAT-50. Thank you kindly

@@garylanders1470 I don’t know what the magnetic signs are composed of or how you would connect a wire to them. Quite possibly they would. The main thing is to make a capacitor of the metal roof by adding a second plate insulated from the roof. You can estimate the capacitance and then measure what you build. Sometimes getting an accurate capacitance is difficult depending on your measuring device. (Long story there) calculating it may actually be more accurate! Comparing it to something that works may also be a good idea. For example we know that the standard 5 inch diameter mag mounts work good for 2 meters. We don’t know the spacing exactly but if I calculate the capacitance of a two plate capacitor with a spacing of 1/8 inch in air I get around 35 picofarads. It is going to actually be more because when you replace air with a dielectric the capacitance goes up. Maybe by a factor of 2 with Teflon and maybe 8 with plane old window glass. So the capacitance could be 70 or 100 plus picofarads. I have never taken the time to try and measure it. So let’s say it’s 100 pf. If that’s the case at 144 MHz the reactance will be somewhere around 11 ohms. At 14 MHz the reactance would be 113 ohms. We know it works good at 144 MHz and also is used by many at 14 MHz. We also know that many guys use a mount with three such magnets with good results on 40 and 20 meters. Using my guestimation that would give a C of 300 pf or three times whatever the single mount really is. It also reduces the reactance by a factor of three. So maybe we get 37 ohms on 20 meters and 75 ohms on 40 meters. In any event we know that an area of about 20 square inches works for 2 meters and 60 square inches works for 20 and 40 meters. At least pretty good. I am out of time here but let me know if you need any additional info on my thinking here. I just scratched the surface here this morning!

Very interesting. Thank you kindly

Wow you are really digging into this. 😉 I just checked the tinfoil is the same size as the MAT-50. The cardboard is bigger as I needed something to stick the (probably fake chinese) Kapton tape on. I measured the capacity using the tape as dielectric not the cardboard. I have no idea how thin the tape is or what dielectric constant it has. - This was one of my famous dumb unscientific hands on “let’s try this” videos. I just wanted to see if I see stunning miracle properties on the MAT-50. I did not. - If you mount your antenna to the roof rail of your car and have connectivity issues it will help. For my 3 magnet mag. mount the effects were not that big on 20m. On 40 or 80m things might look different.

@@labcat73 I watched your video a couple more times! I see the cardboard was on top. So the spacing was smaller than I thought and the dielectric was the tape. That should increase my guessed capacitance a bit. I have been playing with mag mounts for a while and have a 5 inch one. Fine for higher bands but with newer cars and smaller good metal to work with it’s a challenge. I need to measure the capacity of my 5 inch mag mount. I had set it aside and started using a trailer hitch mount on my truck. Not a good ground connection yet. Truck bed is not metal🙁. I am using a few radials that works good. I was thinking of using a mag mount on truck frame to get good capacitive connection. Might need more than one on 40. The MAT -50 is looking like it might work about as well or slightly better than one 5 inch mag mount. It also may fit cleaner on the truck frame. So far I have not tried the triple mag mount. It seems to be a solution but the mat idea, if large enough could be even better.

@@dandypoint Maybe try faraday cloth pinned down by a few strong magnets?! The paintjob of your car is the dielectric then. Not a permanent solution, but maybe cheaper and better than a MAT-50?! Well that’s the fun in the hobby. There is always something to tinker with.

@@labcat73 that’s a possibility. My trailer hitch mount works most of the time. I think it’s got both capacity coupling and direct connection. A good hard connection is probably what I need but not easy on new trucks. I like easy ways to setup!

Probably yes, and this contraption adds another ~2nF to it. To be fair Diamond also advertises it for antennas that are mounted on the roof rail of cars, which might not have the best ground connection either.

@@labcat73 I can certainly see the use for it if you use a roof rail or roof rack instead of a magmount.

Yes i try to do that since October 2023, but then my "How to ruin a mag. mount" accident happened and everything got delayed. I hope to get the video editing done in the next days...

@@labcat73 oh! I'm about to try modifying a sirio one to alloy additional grounding so I'll watch with interest! Anyway this is a great video on it's own thanks! (Have been pondering this item for over a year and can't wait to see if it helps)

@@JohnR_ytbe Well the 3 magnet mag. mount I have with the ampro antenna is already so good to begin with that I did not see any improvement on 10m with the MAT50. It started making a difference on the 20m band. Whatever you do, get yourself a NanoVNA. I can't live without one anymore. What an epic pain finding the SWR dip with a simple SWR meter was in the 90ies... 😱