fringe signal on omni antenna disappears on directional antenna

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Jim S.
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fringe signal on omni antenna disappears on directional antenna

Post by Jim S. » Fri Nov 02, 2018 12:11 am

So I have the WE826 and MC7455 working on Sprint band 25. I wanted to see if I could get a band 41 signal for more speed (my previous hotspot was locked to band 25 by the supplier). Using the stock omni antennas that came with the WE826, I can get a faint signal that varies between about -115 and -124 dB, yielding a SNR that varies between about 1 and negative numbers. Obviously, this isn't usable. However, it does stay locked long enough to get the tower eNB, which I looked up on cellmapper.net and confirmed it's where I thought it was, about 5 miles away with no terrain blocking it but hidden behind trees. So, I got a 1DP1727X15 antenna and hooked it up, pointed in the general direction of the tower, but now all the signal strength and quality values read 0. I'm at a loss to explain this. I assume that the strength must be below the ability of the modem to detect an LTE signal at all, but as the antenna is supposed to be around 15dB gain I can't think that I would be losing greater than 15dB in the cable. It's RG58, which is far from ideal, but I'm only using 6 feet of it for testing. I guess my next step, when the weather allows, will be to try it outside, but meanwhile, does anyone have any idea what's going on?

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JimHelms
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Re: fringe signal on omni antenna disappears on directional antenna

Post by JimHelms » Fri Nov 02, 2018 12:28 am

When using a single external antenna, make sure it is attached to which ever side of the router LTE antenna connector that connects (via Pigtail) to the MAIN port of the modem.

Jim S.
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Re: fringe signal on omni antenna disappears on directional antenna

Post by Jim S. » Fri Nov 02, 2018 1:36 am

The 1DP1727X15 is the one you sell with both horizontal and vertical polarity output. I have both of them connected to the modem. I didn't pay attention to which one was main and which was aux, but I think I did rotate the antenna at some point. I'll have to check that again tomorrow.

swwifty
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Re: fringe signal on omni antenna disappears on directional antenna

Post by swwifty » Fri Nov 02, 2018 7:44 am

A couple of things to point out.

1. I would set this up outside, I see a massive signal strength increase just by going outside. This is going to be true for any antenna setup you have. Also, the higher up the better. I can get a useable 4G signal in my house, but it is much stronger outside.

2. Even though this is a 15dbi gain antenna, it does not mean you'll gain 15dbi of signal (you might get a lot more. read the first post I did here on similar antennas: viewtopic.php?f=24&t=103 I picked up 10dbm! which is about a 10x stronger signal with these antennas). Antenna gain is referring to the direction the RF signal radiates most in (which is during transmit). https://en.wikipedia.org/wiki/Antenna_gain <- You can read more here.

3. It appears from what you said, you only have a single antenna. Like Jim said, if you only have one, be sure you are connecting it to the main port on your modem, not the "aux" or secondary one. I'd highly recommend getting a second one. It will make a significant difference.

4. Be sure to orient the antenna in the proper polarization (this is why you need two of them, since LTE uses a X-pol or cross polarization of two data streams). You'll see an arrow on these antennas that indicate the polarization direction. You'll want to tilt it at +/- 45 degrees.

5. Can you share any screenshots of your signal status off your modem? Any more details always helps. Also, experiment with location as much as possible. It makes a big difference sometimes just small differences in placement.

Jim S.
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Re: fringe signal on omni antenna disappears on directional antenna

Post by Jim S. » Fri Nov 02, 2018 10:19 am

Again, this is a unit with two cross-polarized antennas in one housing: https://ltefix.com/shop/antennas/1700-2 ... l-antenna/

Signal stats with Band 25:

Code: Select all

Current Time:  1188		Temperature: 37
Reset Counter: 2		Mode:        ONLINE         
System mode:   LTE        	PS state:    Attached     
LTE band:      B25    		LTE bw:      5 MHz   
LTE Rx chan:   8665		LTE Tx chan: 26665
LTE CA state:  NOT ASSIGNED
EMM state:     Registered     	Normal Service 
RRC state:     RRC Idle       
IMS reg state: No Srv  		
PCC RxM RSSI:  -82		RSRP (dBm):  -103
PCC RxD RSSI:  -89		RSRP (dBm):  -114
Tx Power:      --		TAC:         5C03 (23555)
RSRQ (dB):     -7.4		Cell ID:     0B805800 (192960512)
SINR (dB):     11.8 
(The difference between the signal strengths on the two ports is because I have the antenna temporarily sitting so that the elements are horizontal and vertical instead of at a 45 degree angle to horizontal and vertical -- but doing it that way gives little or no improvement.)

Signal stats with Band 41 on the router's omni antennas:

Code: Select all

Current Time:  1453		Temperature: 37
Reset Counter: 2		Mode:        ONLINE         
System mode:   LTE        	PS state:    Attached     
LTE band:      B41    		LTE bw:      20 MHz  
LTE Rx chan:   40978		LTE Tx chan: 40978
LTE CA state:  NOT ASSIGNED
EMM state:     Registered     	Normal Service 
RRC state:     RRC Connected  
IMS reg state: No Srv  		
PCC RxM RSSI:  -90		RSRP (dBm):  -120
PCC RxD RSSI:  -92		RSRP (dBm):  -121
Tx Power:      --		TAC:         5C03 (23555)
RSRQ (dB):     -12.3		Cell ID:     0B805603 (192960003)
SINR (dB):      0.2 
(I've disabled CA to reduce the number of variables, as the bitrate is unusable anyway.)

Signal stats with Band 41 on the flat panel antenna:

Code: Select all

Current Time:  1111		Temperature: 38
Reset Counter: 2		Mode:        ONLINE         
System mode:   LTE        	PS state:    Not attached 
LTE band:      No band		LTE bw:      Unknown 
LTE Rx chan:   0		LTE Tx chan: 4294967295
LTE CA state:  ACTIVE      		LTE Scell band:No band
LTE Scell bw:Unknown 		LTE Scell chan:5
EMM state:     Deregistered   	No Cell        
RRC state:     RRC Idle       
IMS reg state: No Srv  		
PCC RxM RSSI:  0		RSRP (dBm):  0
PCC RxD RSSI:  0		RSRP (dBm):  0
SCC RxM RSSI:  0		RSRP (dBm):  0
SCC RxD RSSI:  0		RSRP (dBm):  0
Tx Power:      --		TAC:         0000 (0)
RSRQ (dB):     0.0		Cell ID:     00000000 (0)
SINR (dB):     

swwifty
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Re: fringe signal on omni antenna disappears on directional antenna

Post by swwifty » Fri Nov 02, 2018 10:57 am

oh, my bad, I didn't realize that antenna had two antennas built into it for MIMO. I have a similar version that is non-mimo.

That's some interesting results.

1. Have you tried unlocking from one band, and seeing what happens with the flat panel?

2. I assume you have the flat panel antenna and the omnis in the same position in the house?

3. When you got the signal stats for the flat panel, you had both cables connected for both internal antennas?

4. Also, as far as polarization goes, even though sometimes I don't see a difference in signal stats, real bandwith tests show different when the antenna is properly aligned to the receiving polarization.

Jim S.
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Re: fringe signal on omni antenna disappears on directional antenna

Post by Jim S. » Fri Nov 02, 2018 11:14 am

1. With the modem unlocked, the flat panel goes to band 25.

2. Yes.

3. Yes.

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Re: fringe signal on omni antenna disappears on directional antenna

Post by JimHelms » Fri Nov 02, 2018 12:06 pm

Not sure how (or why you'd want to) disabled CA on Band 41. I would also leave the Bands set to 00 (all bands) and let the modem select the bands. When Band 41 has an adequate signal, I find the modem will generally select it over Band 25.

RG58 cable is not ideal but should be adequate in 6 foot lengths.

You should also move the antennas outdoors to test.

Generally, penetration loss decrease with height so the antennas should perform best at higher level.

Band 41 does not have much penetrating power which is most likely why the modem is choosing Band 25.

The higher the frequency (e.g., Sprint Band 41 at 2496-2690MHz), the shorter its wavelengths, the lower its energy, and the more sensitive its waves to reflection and material absorption. This means the higher frequencies are more challenged over distance and penetration of trees, buildings and other obstacles (which absorb the signals) than the lower frequencies (e.g., Sprint Band 26 at 859-894MHz)—which have longer wavelengths, more energy and deeper penetrating power with less absorption.

This places an indoor directional antenna at a disadvantage since it does not have the ability of harvesting signals that are being bounced, reflected or scattered that are accessible indoors to the omni antenna's 360 degree rotation.

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