My seconds Homemade antenna

AlmostHandy · #1 (**permalink**) 01-26-2009, 02:35 PM

My second homemade antenna is a Biquad tuned to 2.4GHz, mounted on a dish. This was a Trevor Marshal Design. I got impatient, and really wanted to hook this thing up. As a result, there are many things I'd like to change about it. like my last antenna, there will be a revision as soon as I can afford it.

I based it on a 110MM square piece of PCB. A simple 30.5mm Biquad element attached to a UHF chassis mount soldered to the board. Mounted on a hogged out LNB from a Dish Network Dual LNB dish. I have a friend with another dish. His is a DirectTV model with a Single LNB. I think it will be easier to work with and configure.

On a tight budget, I was able to find a few surplus parts, and throw together a feedline made from RG-6. In a few weeks, I'll upgrade that to LMR400 with a pigtail.

What do you know? It freaking works, and it works well. There is a public library about 3/4 mile up the hill. With the dish, I get 19-22db more signal than I do with the omnidirectional antenna I had before.

I plan to mount the dish to a Rotor on the top of a mast, eventually.

I really like making antennas.

I think I'm going to make a Yagi next.

n4yek · #2 (**permalink**) 01-26-2009, 03:07 PM

Looks great, that would definitely be directional.

AlmostHandy · #3 (**permalink**) 01-26-2009, 03:18 PM

Yeah, it works great. I can't wait until I can hook it up to a decent feedline.

One of my next projects is to find a cheap GPS receiver so I can map all the AP's with Netstumber and Google Earth. I was looking at the Garmin GPS18. It's only about $50 on ebay. Does anyone know of a cheaper GPS receiver? I plan to research it more when I'm ready to buy (Yay tax refunds!), but I'm definitely open to suggestions in that area.

k8mcn · #4 (**permalink**) 01-26-2009, 04:50 PM

nice job---let us know how it works with the lmr400 and on the rotator. I just picked up a couple of dishes from Freecycle and am intending to make one like yours

AlmostHandy · #5 (**permalink**) 01-26-2009, 05:09 PM

Right on! It's really easy. The hardest part is knowing where the hell to aim the thing. I currently have to check my Netstumber, run outside and make an adjustment, run inside and check netstumbler, run outside and make an adjustment, etc.etc. I can't wait to get that GPS unit and map this area.

The beam on this thing is really narrow, and the H plane is really deceptive with the shape of the mount, since this is a Dual LNB dish, it's a little taller, and the sidelobes are smaller. On my next model, I'll be adding the 29mm lips to the ground plane. After studying the pics of my friends DirectTV dish, I've decided that the DishNetwork dish is not the way to go. When I get the LMR, I plan to do some real testing to see how far I can reach with it.

The line of sight is great from my location. I can see the south face of First Hill. It'll be much better when I put it on a mast to clear the local power lines and trees. I only need to go up about 25 or 30 feet to get a great view.

bballjh · #6 (**permalink**) 01-26-2009, 05:13 PM

I see you've been bitten by the antenna creating bug. The two you have created so far look great and I'm sure they offer a big improvement! Keep it up.

prcguy · #7 (**permalink**) 01-26-2009, 09:58 PM

You mention its got a UHF chassis connector, do you mean an SO-239? Uggg!
If you are going to use this with a GPS you will log your location for every access point even though the antenna is picking up from several blocks away. The location of the GPS antenna is what shows up with Netstumbler.
Instead of running a long feedline which will kill all your signal see if you can remote the wireless card at the antenna. Its better to run a 30ft USB cable and no feedline if possible.
prcguy