GRA MAT50 HF Ground Enhancement Mat for Mobile Screwdriver Antennas, Improves SWR and Ground Coupling for 7 to 50MHz, Dual Pack Support for 3.5MHz

Quite functional, works well to adjust a mobile antenna's ground plain and general experimentation. The magnetic pad sticks well to my car for good contact. It's easy to install and remove so it's portable. I've used mine for weeks now and I must say that I have seen changes in signal strength based on frequency and antenna. Do your research first.

I bought a Yaesu ATAS-120A antenna but had problems getting it to work on the 20 meter band when mounted on a mag mount on my van roof. SWR was too high. I bought the GRA-MAT50 MK2 counterpoise magnet mat ground plane and tried it again. My FT-710 tuned on all bands between 40 to 6 meters with a good SWR while testing, I made an SSB phone contact with a POTA activator in Spain on the 10 meter band. Excellent! I'm pleased with this magnet mat ground plane.

I picked up the GRA-MAT50 MK2 Counterpoise Magnet Mat to pair with my magnetic mount and HF antenna, and I’m left with mixed feelings. On the positive side, it’s a clever concept with an interesting form factor that magnetically attaches to the car, making it super easy to use. However, I’m not convinced it actually improves performance, at least on HF frequencies—it just doesn’t seem to make a noticeable difference. Perhaps it might have more impact on VHF or UHF, but for HF use, I’m not seeing much value. While it’s a cute and innovative idea, I can’t justify giving it more than a 3 out of 5.

I use the GRA-MAT50 MK2 with my Yaesu ATAS-120A antenna on a mag mount in the center of my minivan roof. Before connecting the GRA-MAT50 to the antenna, my SWR on 40 meters was about 2.3:1, which is not terrible, but could be better. Once I connected the GRA-MAT50 to the antenna, my SWR on 40 meters went down to about 1.4:1, which is pretty good. I did not notice any improvement in SWR on other bands (10,12,15,17,and 20 meters) because the Yaesu ATAS-120A is able to tune those bands good on its own without the GRA-MAT50. But the improvement on 40 meters makes this purchase worth it. A friend of mine also uses the Yaesu ATAS-120A on a mag mount and he has the same higher SWR problem on 40 meters. So he is considering the purchase of the GRA-MAT50 to help with 40 meter SWR. Even though the GRA-MAT50 did not make a difference on bands other than 40 meters with my Yaesu ATAS-120A, it might help with my transmit signal somewhat anyway by creating a more efficient counterpoise by helping to increase the capacitive coupling of the antenna to the vehicle.. I have another mag mount antenna, (Hustler MO-2 with resonators) but I have not tested the GRA-MAT50 with that antenna. If I do test it with that antenna, I will submit that review. I would think that the GRA-MAT50 may probably help with that antenna too since the bandwidth with the Hustler MO-2 on a mag mount is quite narrow on 40 meters, and the internal tuner of the radio is not able to get the SWR real low on 40 meters. So, what is generally known about a mag mount antenna on the HF bands, the lower in frequency that you get, the less effective a mag mount antenna can be, most notably 7 mHz or lower. But the GRA-MAT50 can help with that. Bottom line, I recommend the GRA-MAT50, especially for 40 meters.

Work great with ATAS Antenna

Not even one year!! I am antenna challenged individual. Long story. So I run a longer piece of coax out of the garage and throw a mag mount Stryker A10 on the car to talk with the group. I never really had any SWR issues but I saw this product and thought it couldn't hurt. It was pretty expensive. It arrived and I in stalled it and sure enough my SWR went down a smidge, great! And it never came off the antenna once installed. But understand this antenna is take off a shelf in high ceiling garage once or twice a week and left overnight on car. The rest of week it is indoors on a high shelf. Also maybe taken mobile up on the "mountain" 3-4 times a year as well. And unfortunately you can see by the photo it less than a year the wire has broken and it almost fully detached. And how I noticed it: all the sudden my SWR's ticked up a bit. Great product, cant hurt, but if it only last less than a year the $$$, I WILL PASS.

If you are using a an HF mobile antenna on a car with any kind of mount, the mat will ensure that the ground side of your coax feedline is coupled to the car body. I performed measurement on the capacitive coupling, and the manufacturer's claims of frequency coverage from 7-50 MHz are absolutely correct. The mat, which is magnetic itself, is easy to apply snugly to the car, yet is also easy to remove. This is a nice piece of simple and elegant engineering. Definitely recommended.

Looking at this made me think. Could something this simple really solve the noise issue in my mobile setup? It looks well built. Solid connections. It might work. Lets give it a shot... Installation was straightforward and simple enough. Unscrew the antenna, slip the ring connector over the SO-239, screw the antenna back on. OK. Did it work for me? In a word, no. It actually made my SWR and noise floor worse. Unusable. I ended up going from an S5 to an S9+ on all bands with this installed. I got nothing but static and high frequency warbling. It might work for you, but it didn't for me. Sorry.

Great product. I have 3

Great item that arrived in only 7 days from America.

This item flew off my car roof when we were travelling at 45 miles an hour and I haven’t seen it since. It was useful for the 25 minutes I owned it.