Yesterday evening PA2AYX and me managed to establish our first reliable long range Wifi connection. Before we did, I replaced the 16-element Yagi by a Grid Antenna, because I had some doubts about the Chinese-made thing. In the end this proved to be unjust, but I left the Grid on my roof anyway. The advantage of a Grid instead of the Yagi is the smaller opening angle, 14 degrees instead of 23 degrees. Gain is about the same, 24dBi versus 25dBi. Some more accuracy is required when pointing the antenna to the other station though.
We agreed that my system would be set up as an access point, and Dirk’s system would be configured as a client router. The way this works is easy to understand: client means that his system is configured to pick up a host (my access point), and router means that his system will hand out IP addresses to all the connected clients.
Setup at PD0AC
Grid Antenna – EnGenius 2611P (AP mode) – Switch – Modem/Router – Internet.
Setup at PA2AYX
16-element Yagi Antenna – EnGenius 5611P (client router mode) – Switch – Clients (desktops, notebooks)
Internet speed was fine at Dirk’s end. Later in the evening Dirk upped the stakes by hooking up his D-Star repeater to the system. To our surprise, this worked without a hitch. Speaking of stealing bandwidth!
Plans for the coming days: bridging
The next step is to connect our two wired LANs by putting both EnGenius system into bridge mode. Some adjustments have to be made before we can do that. Both our networks reside in the 192.168.2.xxx range, and that isn’t going to work. After all, bridging is all about connecting two networks which can’t see each other because of incompatible IP-ranges. I will change my network to reside in the 192.168.1.xxx range instead.
Both EnGenius systems generate 28dBm, which equals to 600mW. In our setup there are no cable losses to take into account. When converting this to ERP or EIRP, this is what our antennas spit out:
OK, not enough to fry a bird sitting on our antennas, but impressive nonetheless. And slightly illegal, so we keep our systems on the air as short as possible.
The answer is: Fail. We won’t abort though, but retry. When we were setting up our long range WiFi network, we ran into some problems. At PA2AYX’s side, everything is fine. At my end it’s not. The 16-element Yagi, bought on eBay for less than $15, is fine. My access point (TP-Link TL-WA5110G) is fine. Power output is fine. The coax cable between the AP and the Yagi is not. Far from it, to be exact.
Scam, scam, scam
When I ordered the 10 meter long cable, it was advertised as “low loss cable for 2.4 GHz’. When the cable arrived, I quickly realized that I got scammed. The cable proved to be ordinary RG-58, a cable I would only use for HF, nothing else. So here we are, most of the Yagi’s gain is eaten up by a poor cable. 10 meters of RG-58 @ 2.4GHz equals a loss of at least 10 dB, probably more. 10dB is a lot – both RX sensitivity as well as TX power are divided by a factor of 10. LMR-400, the cable I expected to get, loses only 0.22 dB per meter. This means 2.2dB cable loss, which is more or less acceptable. Better numbers, sure, but dangerously close to 3dB, a factor of 2. Here is a list of cable losses, at 2.4GHz:
- RG 58: 1 dB per meter.
- RG 213: 0.6 dB per meter.
- RG 174: 2 dB per meter.
- Aircom: 0.21 dB per meter.
- Aircell 7: 0.38 dB per meter.
- LMR-400: 0.22 dB per meter.
In spite of the crappy setup at my side, my signal came through. The distance between our two stations is a little bit more than 1 Km, and we don’t have a completely free line of sight. There are some trees in the way, plus a sporting complex. All in all not bad, but not good enough. My setup will be changed completely. I don’t want to calculate cable losses at all, so I ordered an access point which can be mounted directly under my Yagi. These nifty devices are made by EnGenius and other companies. The power output varies from brand to brand, but the options are more or less the same across the board: AP, repeater, and bridge. Power is supplied by POE (Power over Ethernet), the only cable going down into my shack is an ordinary Ethernet cable.
Long range WiFi networks: what not to do
If you own a low power access point, don’t buy so-called ‘boosters’. Apart from the fact that they’re often very unreliable, these things won’t solve your problem. Invest in a hi gain outdoor antenna and low loss cable instead. If possible, replace your ordinary AP by something like the EnGenius EOC-2611P, and put it high up in the air.
Within a week or 2 we will be able to report failure or success. I expect the latter.