I cannot get 20 feet from the unit before I lose signal

RouterOS Wireless Networking
1

I have a Routerboard 500 with a Atheros AR5413 radio installed. I have installed this unit in a weatherproof box with 2 female N-type connections. I have run 2 30Ft Hawking HAC30N low loss extension cables to 2 Hawking HAO9SIP 9db high gain antennas.

Now when I run the unit without any antenna’s attached, I get about 35 to 40% signal strength at 5 feet from the unit on my iStumber and WifFi meter.

When I attach the antennas to the unit directly via the N-Type pigatils, I get 50 to 57% signal strength at 5 feet from the unit.

When I attach the extension cables to the unit with the antenna’s attached, I get 50 to 57% signal strength when I am less than 5 feet from the antenna’s.

When I walk less than 50 feet away, my signal is gone. I cannot see the AP on the iStumbler or my WifiMeter..


I obviously have an issue here. I do not seem to be able to find any software or tools that will show me the actual wattage coming off the wire or the actual radiated power. This is a 400mw radio. At 9db gain, I should be able to get more than 50 feet away. I’m obiviously missing something and I don’t have the experience or tools to figure this out.

Anyone feel like giving a newbie guy here the rundown on how to get the actual wattage readings and radiated power? Or can someone maybe point me in the right direction. The radio is set all default running at 2.4ghz b/g channel 1. Do I need to ramp the power up on the radio from 17dBm?

Any ideas or can you point me in the right direction?

2

I had less power going with a WRT54G with a 10.5 omni and got 1/8 mile coverage through trees.

something is wrong with your hardware or config.

have you tried a different antenna port? it should be absolutely screaming at 5ft.

3

I assume you’re walking 50 feet away with clear line of sight? If you’re going through walls or trees, then 50 feet may well be the best you’ll get at the stated power levels. I’ve had instances in old houses with thick walls where the signal will barely go 15 feet!

Sounds like you’ve got your antennae setup wrong. If you’re using two then you need to setup the radio card to TX on A and RX on B or vice versa, this is known as diversity. You actually only need one antenna connected to A or B connector and card set to TX/RX on the appropriate connector.

You might have a fault on one antenna or connector. I would setup the system to only use one antenna, then you can try each in turn to see if there is any difference. Also try switching between connector A and B on the wireless card to see if the card is faulty.

Incidently 9dB and High Gain mean opposite things, a high gain antenna would be 26dB+. 9dB is actually pretty low gain. You can get Omnis up to 15dB, but I wouldn’t recommend them, 8 or 9dB Omnis work better.

If your wireless card is set to 17dB, then your EIRP would be 26dB excluding cable loss. 17dB = 50mW, you could ramp up your TX power to 26dB = 400mW, however be aware of the legal limits on EIRP in your locality. Assuming you’re using 2.4GHz band, max EIRP in Europe is 20dBi or 100mW. In the USA you’re allowed upto 30dBi or 1W with an omni directional antenna, you’re allowed up to 36dBi/4W with directional antennae.

4

That makes a lot of sense. The default tx power is 17dBm. I set it to 26dBm. I won’t be able to do a test until Monday. So lets see if that helps.

I am looking for a way to actually plug into the pigtail, and extension cable to find out what my actual output wattage is. How do i do this? What tool do I need?

I want to find out how much loss I have or if I’m even getting the maximum power out of the radio. I want to see if I’m acutally getting 400mw at the pigtail.

How do I generate a lobe pattern? I want to actually read the erp from the antenna and figure out where my dead zones are. I know that by running a gain antenna, that the lobe will not be an equal omni. Its gonna start taking a direction due to the gain. As one of my friends have told me, you don’t get something for nothing.

Thanks!!

5

Lobe patterns can really only be generated in special labs with chambers that are anechoic to radio frequencies, otherwise reflections and other background noise will give false results.

You can get RF meters, but I don’t know where or how much. Someone else posted in another thread that he’d bought one and someone has asked him to give details.

The horizontal lobe pattern of an Omni is theoretically a circle irrespective of gain, in practice it will be an irregular circle due to manufacturing tolerances.

Don’t forget that lobe patterns usually show the 3dB contour, i.e. the point at which half power is received. It doesn’t mean there is no signal outside this contour, just that the radiation pattern hasn’t been tested.

With lobe patterns you need to think in 3D:-

A 0dB antenna, i.e. a cable with no antenna connected, will radiate a pattern roughly spherical with the middle of the sphere being the end of the cable.

With Omni-directional antennae the sphere becomes like a ring doughnut, being squashed flatter the higher the gain, but still radiating 360 degrees in the horizontal plane. High gain Omnis, e.g. 15dB, can be good for long distance, but generally have a significant dead zone local to the antenna. Medium gain Omnis are best, e.g. 8 or 9dB, as this gives the best compromise between distance and minimising the local dead zone.

Directional antennae focus the signal into a cone that becomes narrower the higher the gain, the signal is predominantly in one direction, but you can get significant side and rear lobes at 90 and 180 degrees to the main signal, these can either be a nuisance or with good antenna siting can be beneficial, reaching users that would otherwise need a seperate antenna.

6

I have tried the setup on a RouterBoard 112 and RouterBoard 133.
I have a Senao NMP-8602 Wireless Card in Slot 1.
I have a 2 omni 9dB gain antenna.
I have set the card to use antenna a and on another test antenna b only.
I have set the card to use a-tx/b-rx with 2 9dB antennas.
I have set the card to use a-rx/b-tx with 2 9dB antennas.
I have the antenna’s plugged into a 8 inch N-Female pigtail right off the card.
I have set the card from 26dBm to 10dBm. Just to see if I get a big change. It doesnt seem to change that much sitting right next to it, but when I walk away, it drops off pretty quick.

Now.. No matter what I do, I can only get about 50 feet away from this setup before I have nothing. Zip. Zero. It drops off.

When I sitting on top of the unit, I get at best 80% signal strength. When I unplug the pigtail, I get 40% signal strength. These measurements are being made with iStumbler on Mac OS X.

I have tried an 12dB directional antenna and gained about 5 feet more.

Anyone have any clue as to what I’m doing wrong? I already figured out that my extension cables (RG-213) were crap so I dropped them from the test unit. I am running with the antennas plugged in as close as I can get them to the actual card.

Help?

And yes.. I am aware of the signal regulations and requirments of my area. I can’t get 50 feet from the unit at 400mw with 9dB of gain. I definatly am not causing any RF issues yet. When it works right, I’ll drop the power back and make sure that I’m in compliance.


Thanks a million!!

7

I keep reading about people having issues getting 500 meters from their ap with a 5dB antenna at 400mw. I can’t get 12 meters away from my unit.

I gotta ask and I hope that everyone will be kind. AM I JUST STUPID?

I can’t seem to get this Mikrotik Routerboard 112 with a Senao NMP-8602 400MW radio to work. It doesn’t seem like it should be brain surgery. I’m not using any accessories that are weird or bargin basement items. I’m using a standard 9dB omni plugged directly into this unit and I can’t get 15 meters from it at 400mw. I gotta be missing something. The card is not making power or something.

I can’t tell you how frustrated I am. I’m sure when I find the fix I’ll want to slap the crap out of myself.

Any help is appreciated. Thanks!!

8

Have you tried another radio card, someone posted somewhere else that these cards are very sensitive to static discharge and you can very easily damage them.

What are you using as your test rig? Have you tried a different radio card in that? Some built in Laptop radio cards are really poor.

I have also tried Senao 8602 cards, but I can’t even get as far as testing them. As soon as I enable the 8602 they crash the router, I’m working on a PC chassis rather than RouterBoard. I bought 10 of the Senao 8602 cards and they all seem to behave strangly, I think it’s unlikely to be a card problem in my case so I think there is some fundemental incompatibility with the Senao cards and RouterOS.

I did report this to MT support, but they fobbed me off with “no one else has reported this”, not very helpful. Clearly other people ARE having problems.

I’m using Wistron CM9 cards now which are OK, but I still seem to get the odd crash, so at some point I’ll have to buy some R52 cards to see if they work any better.


Regards


Chris Macneill

9

I have been testing it with a WiFi network detector, MacBook Pro with iStumbler and a Acer Laptop with a Intel ProSet card running Netstumbler.

All of the devices seem to see the same amount of power from the unit. I Have a business just behind mine with a Airport Extreme and they are coming in stronger than this unit. I also have another business near me that has a Linksys WRT54G and they are also coming in stronger than my unit sitting on my table.

I do not have another type of wireless radio to check in this unit. I am starting to think that you are right about the radio card. I bought 4 of them and they all have the same issue. I have eliminated everything I can think of that might cause me trouble.

I’ll see if I can round up a different card and see what the results are.

Thanks for the continuing help! This forum rocks..

10

After reading a lot about the Senao cards, I have decided to dump them and go with a nice Ubiquity card. Let’s see if I have better luck with those!


Thanks a million for all the reply’s and help.

11

You may wish to verify that the antenna connector is correct for the setting you have used in Router OS.

I would assume that the antenna A is selected in RouterOS, instead try the antenna B.

It could be you have the pigtail in the aux antenna connector instead of the main.

12

Also sounds to me if your diversity switch on the card popped. Have you tried another card and it is ok now?
I have a bag full of cards that ‘popped’. They work, but limited range and poor performance. Make sure you ground the omni’s or use sectors. There is another post explaining grounding of omnis.
I’m still looking for a way to remove the diversity switch and have full RX/TX on one antenna… Anyone?

13

I have had nothing but problems on the 8602 and RB112. I have had better luck with the RB532, but it was always providing a very weak signal level. Switched to SR2 cards and it works MUCH better.