Last week we looked at the ImmersionRC 5.8GHz stock antennas, this week we're going to take a look at the stock antenna for a Lawmate 1.2GHz system. These come standard with all your Lawmate branded equipment.
Depending on where you live, your available channels which you're allowed to transmit on may vary. The receiver has channels from 1080MHz-1280MHz.
For all of these tests, I'll add markers 1 and 2 at 1.25:1 (1.235% loss), and markers 3 and 4 at 1.5:1 (4% loss). You can see the frequencies that these match at in the top right of the pictures. A VSWR of 1.25:1 is very good, even 1.5:1 is good from a radiated power standpoint, however most antenna manufacturers would consider this to be a poorly matched antenna.
So how does the antenna look?
1.5:1 bandwidth is 1.2GHz to 1.28GHz.
This antenna really isn't so great for it's intended purpose. If you are able to use the HobbyKing version or the GetFPV version channels then you would be best on 1240MHz, which has an almost perfect match. If you're using the HobbyWireless version (they have two??) then I guess the 1258MHz channel is the best?
My problem with this antenna is that it is meant to work from 1080MHz (Marker 6) up to 1280MHz (basically Marker 2). At 1080MHz you have almost 24% of the energy coming straight back into the transmitter, which means a lot of heat - especially if you are flying a a 1GHz transmitter.
The tests here are with the antenna pointing up at the sky. I'm pretty sure they are a monopole antenna, so the ground being "down" is important for them to perform well. I know some people question "what happens if I put this upside down in my plane". Well, here's the answer (same marker positions as before):
It doesn't perform as well. Keep it pointy side up. As a note, I'm on the 3rd floor here and there is no significant metal or ground sources anywhere near the antenna to cause detuning. This will be an interesting test to do with Spironet antennas, as Rob often flies with them pointing down, and I've told him thats just fine to do.
I'm not going to test this antenna with a hand next to it, as I can't really imagine anyone sticking the Lawmate receiver on their goggles, unless those goggles are already so bulky that the receiver won't be right next to the head anyway.
My rating: Great for 1240MHz, rubbish for everything else.
This is just a stock antenna, if stock antennas were amazing there would not be such a large market for upgrades. I've found that transmitters run significantly hotter with these antennas than with a decent quality antenna.
Where can you buy one?
I don't believe these are available individually, nor would I recommend trying to hard to find one.
Do you have an antenna you would like to see tested?
Please Contact Us, if you're happy to pay postage to us - we will test it, and pay the return postage to you.