Broadband Yagi + USB Stick + USB Cable + Antenna Cable - Page 1
Forum section: electronics / beginners

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 05, 2011, 04:09:27 pm
content: I'm having poor internet broadband signal indoor. Currently use a long USB cable to put my USB stick outdoor on a vertical broomstick. Works better, but today (weekend) i think i've been outrun by many neighbours, so i still got poor reception. I will build Broadband Yagi Antenna to put outdoor for my USB Broadband stick. got some question:1) Which is better in reception?a) usb stick indoor on the pc usb port, long antenna cable to yagi outsideb) usb stick next to yagi outside, very short antenna cable, long usb cable to pc insidethe problem with long usb cable is i usually got "cannot make high speed usb comm" or something like that in pc, i prefer (a) but not sure how much long antenna cable will decrease yagi performance. long cable i mean is somewhere like 3-5 metres (yagi to pc)2) what type of cable best for this small broadband yagi?hope some advice.

author: johnwa
author_rank: Frequent Contributor
timestamp: March 06, 2011, 12:48:22 am
content: Hi,I have got a similar situation here - signal strength around 25-30% and frequent dropouts. I am planning to try using an external parabolic reflector to improve the signal strength. I think the USB 'dongle' has an antenna socket on it, but I was going to try installing the dongle directly at the focus of the dish, without using the antenna socket. I did a quick test with the modem and reflector hand-held inside the (steel framed) building. This did not show much improvement, but I hope with the unit outside, higher up, and rigidly mounted, it will work a bit better.As far as cabling goes, given the high frequency of operation, I would suggest keeping the RF cabling cabling to an absolute minimum to avoid losses. But of course the USB is only designed for a few metres too. One possible solution would be to get a broadband router with a USB port for 3G internet. This could be installed up the mast with the USB modem and antenna, and you could run ethernet back to your computer, which will easily go 100m +. I have got a netcomm N3G007W router - it does seem a little unstable at times, but I am sure there are other devices available with this functionality.Hope this helps,John

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 06, 2011, 03:53:31 am
content: thanx john. but router will need additional cost and setup (power supply to outdoor) etc. will keep your suggestion as an option. if rf cable is ineffective, maybe i will just try to put the yagi next to my pc and point it out to window.

author: GeoffS
author_rank: Unknown
timestamp: March 06, 2011, 07:32:03 am
content: You didn't mention what frequencies you were interested in but if it's a 3G wireless broadband,here's a simple, cheap design.There's a comment in the text about co-ax quality and length. The builder is using 20 metres of low loss RG58 and still gets good results.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 06, 2011, 10:10:08 am
content: sorry forgot, its WCDMA or HSDPA, but HSDPA is preferable connection. if not good transmission, i'll get EDGE or even worst GPRS. from my last search i think its 2++GHz (HSDPA or 3G), but i'm not sure. here is my referencehttp://www.skyscan.ca/Antennas.htmfor broadband yagi antenna design and length calculation. Thanx GeoffS. but confuse me about the "Next G" 800++MHz BW. i'll get back to it about the coax cabling.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 07, 2011, 03:35:59 pm
content: it works! it works! my diy yagi's working! the reference is as mentioned above, i repeat herewww.skyscan.ca/Antennas.htm. so this is for real, not a marketing crap. i just follow the length calculation guide and material, and this is no sweater, i just construct in one go and try out, and it works! even though poor workmanship and i havent make alignment, performance tuning and havent glue and paint the elements yet, they will fall down if i rotate it vertical. so no more go outside to stick the modem, and no more dog barks!so mr yagi's rockin'! with condolencence to him, let me leave my "quick made" software for mr yagi's antenna length and spacing calculation for others to benefit (yagi.zip, windows only sorry). adios!

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 12, 2011, 05:30:45 am
content: this is science, and work on any rf frequency any device. 1st thing to know is what frequency your device is operating, and the rest are the links provided here.and of course you need to find out how its going to be connected to your device's antenna input. mine is using crc9 connector, so thats what i'm looking for.

author: ArtemisGoldfish
author_rank: Regular Contributor
timestamp: April 15, 2011, 09:55:53 pm
content: Quote from: Mechatrommer on March 05, 2011, 04:09:27 pm1. It's usually best to have the RF transmitter/receiver as close to the antenna as possible, but if the USB signal isn't going to get far enough, you have to compromise.2. If we're talking fairly high frequencies, I'd go with something like LMR-400. The loss for 1.8GHz at 100ft is 5.7 dB, which is pretty good.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 16, 2011, 06:41:59 am
content: last time i browsed, iirc lmr400 is semi rigid cable. now i have the antenna closer to the modem (~1.5m) but the cable can be extended to 3m, so now its winded and hanged somewhere, is that considered close? which one matter? the distance of antenna and unit? or the cable length connecting them?