IoT M2M blog

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BG95 / BG77 antenna selection and antenna matching

Quectel BG77 features

Quectel BG77 features

In order to save development and approval costs, the antenna, frequency bands, groundplane size and housing should be at the beginning of development. If the company lacks in-house experience with radio, antennas and worldwide approval, we recommend consulting an external consultant. The following text is intended to make you think. I use real radio networks in my district. I’m using the Quectel BG95 and BG77 for the consideration, because with its 20 frequency bands, option on internal Wi-Fi and GNSS exterm it offers many possibilities for applications. I explain it in detail on BG95-M3 because it is supporting NB-IoT, LTE-M with fallback to GPRS.

Cellular Bands with Quectel BG95-M3

NB-IoT and GSM with BG95-M3

LPWA frequencies in comparison

LPWA frequencies in comparison

The BG95-M3 is covering 20 bands for NB-IoT and LTE-M plus 4 bands on GSM. The supported bands of BG95 we marked yellow in the table as below. For the European bands, we used blue characters. Band 31 with its 450 MHz is very special and not very popular in public LTE networks. In Germany utility companies running closed LTE networks in the 450 MHz range. NB-IoT in Europe is mainly on band 8 and 20. Deutsche Telekom in Germany is running a dual band NB-IoT network on SubGHz band 8 and 20. Vodafone in Europe is on band 20. It is common to run NB-IoT on SubGHz bands.

LTE-M with Quectel BG95-M3

LTE-M you could run at SubGHz but in parallel to LTE 1800 in EU or LTE 1900 as well. For Germany I expect band 8 an band 20 from 791 MHz to 960 Mhz. I analysed the LTE network in my district Neustadt am Rübenberge. The fall back for voice for LTE 800 is GSM 900. This means LTE 800 and GSM 900 are at same antenna mast up to the same physical antenna and some BTS on single RAN. One BTS is able to run everything in parallel. LTE-M is mainly a slow LTE CAT 1. The operator will use the same BTS for LTE-M as well. This means we get LTE-M in the same bands like NB-IoT. LTE 1800 and LTE 2600 they run in the bigger cities to achieve the 450 Mbit per second and more for the smartphones. In my dreamy little town we are happy that we have LTE on a carrier with 150 Mbit per second, 1 Mbit at the edge of the cell and phone calls on GSM. On top of that we have coverage in over 30 villages with GSM, LTE and NB-IoT.

NB-IoT coverage in Neustadt am Rübenberge / Germany

NB-IoT coverage in Neustadt am Rübenberge / Germany

The old district Neustadt am Rübenberge is well supplied with NB-IoT from Vodafone. The coverage map for LTE from Vodafone and Deutsche Telekom is overlaid in the graphic. Telekom does not offer NB-IoT yet. So we test with Vodafone for now.

Antenna matching or Quectel BG95-M3

If you want us to match your antenna for the Quectel BG95 or BG77, other cellular modules or even LoRaWAN or Sigfox you have to consider the required bands. If we are to match for the USA and Australia or even develop customer-specific antennas, then the cellular frequency bands must be named with the order for antenna matching. In order to save costs for antena matcing, antenna development and approval, the radio module like BG95 or BG77 can be limited with control commands. For Neustadt am Rübenberge this means that NB-IoT in band 20 and GSM in band 8 are enough. If you want to work with all network operators in Germany together, then you should choose band 8, band 20 and band 3 with NB-IoT (band 8 and 20), GSM (band 8 and 3) LTE-M (band 8, 20 and 3). For the antenna it stays at 3 bands and matching for 3 bands. However, 7 control measurements on the harmonic waves are necessary for radio approval at notified body. If we execute an order for matching or antenna development, then we measure the bands at 2100 MHz and 2600 MHz in Europe at the same time. However, if only bands 8, 20 and 3 are required, then we do not try to optimize the upper bands. If you know exactly that you only want to sell your device in Europe, then you can choose the remaining bands and do without multiband in the USA or bands above 2100 MHz. The return loss curve will look better for an antenna for 3 cellular bands than for 5 or even more bands. Less is more. You get the rest of the remaining is better. If the bandwidth of the antenna becomes limited due to a small ground plane, then this works better with 3 bands than with 5 bands.

Testing antennas for Quectel BG95 and BG77

The best way to do this is to mount the embedded antenna in the housing on an empty PCB first. The data sheet of an antenna is only a rough guide. The antenna is in the real world with housing always worse than on evaluation board of the manufacturer without housing. Everyone always wants low-cost and 10 years from the battery. Such a long-term battery quickly costs 20 USD. With 1 USD more for the antenna you often save 10 USD for the battery. 3 dB antenna gain often means half the current during transmission and thus half the energy for a message. The antenna is the key to success, range and 50% battery savings. If the antenna is perfectly adapted in the motherboard as a printed circuit antenna then you save the chip antenna. A customized, stamped metal surface, bent often leads to a very good antenna and the costs for the development are saved with the battery again.

Offer for antenna matching or antenna developement

In order to make an offer for matching or development of an antenna we need:

– The frequency bands and the countries

– Type and name of the radio module

– Size of the board, equal to the size of the ground plane

– Application of the device

– Housing material or data sheet

– Battery, display and other metal parts in housing

– Planned installation type. We will simulate the ambient conditions

As stated in the introduction of this article, at the beginning of development you should carefully consider in which regions and bands you would like to sell your device. If the antenna or the size of the ground plane does not match the frequency band or the bandwidth of the band, an approval may not be possible. If there is no experience with radio approvals worldwide, we will be happy to help you with advice on a small budget. In my function as Sales Director, my customers often receive basic advice free of charge. Inquiries for consulting, feasibility studies, development of IoT devices, matching of antennas or development of customized antennas are welcome at harald.naumann (at) lte-modem.com

Frequency band supported by Quectel BG95-M3

BG95-M3 LTE bands: B1, B2, B3, B4, B5, B8, B12, B13, B14, B17, B18, B19, B20, B25, B26, B27, B28, B31, B66, B71
BG95-M3 GSM band: B1, B2 B3, B5
Data sheets Quectel BG95 and BG77

B
and
M
ode
ƒ
(MHz)
N

a

m

e

Subset of band Uplink
(MHz)
Down-

link
(MHz)

Duplex spacing
(MHz)
Channel BW
(MHz)
1 FDD 2100 IMT 65 1920 – 1980 2110 – 2170 190 5, 10, 15, 20
2 FDD 1900 PCS
/GSM 1900
25 1850 – 1910 1930 – 1990 80 1.4, 3, 5, 10, 15, 20
3 FDD 1800 DCS, GSM/LTE 1800 1710 – 1785 1805 – 1880 95 1.4, 3, 5, 10, 15, 20
4 FDD 1700 AWS 66 1710 – 1755 2110 – 2155 400 1.4, 3, 5, 10, 15, 20
5 FDD 850 Cellular
GSM 850 / LTE 850
26 824 – 849 869 – 894 45 1.4, 3, 5, 10
7 FDD 2600 IMT-E 2500 – 2570 2620 – 2690 120 5, 10, 15, 20
8 FDD 900 Extended GSM
/ LTE 900
880 – 915 925 – 960 45 1.4, 3, 5, 10
10 FDD 1700 Extended AWS 66 1710 – 1770 2110 – 2170 400 5, 10, 15, 20
11 FDD 1500 Lower PDC 74 1427.9 – 1447.9 1475.9 – 1495.9 48 5, 10
12 FDD 700 Lower SMH 85 699 – 716 729 – 746 30 1.4, 3, 5, 10
13 FDD 700 Upper SMH 777 – 787 746 – 756 ?31 5, 10
14 FDD 700 Upper SMH 788 – 798 758 – 768 ?30 5, 10
17 FDD 700 Lower SMH 12, 85 704 – 716 734 – 746 30 5, 10
18 FDD 850 Lower 800 (Japan) 26 815 – 830 860 – 875 45 5, 10, 15
19 FDD 850 Upper 800 (Japan) 26 830 – 845 875 – 890 45 5, 10, 15
20 FDD 800 Digital Dividend (EU)
/ LTE 800
832 – 862 791 – 821 ?41 5, 10, 15, 20
21 FDD 1500 Upper PDC 74 1447.9 – 1462.9 1495.9 – 1510.9 48 5, 10, 15
22 FDD 3500 3410 – 3490 3510 – 3590 100 5, 10, 15, 20
24 FDD 1600 Upper L?Band (US) 1626.5 – 1660.5 1525 – 1559 ?101.5 5, 10
25 FDD 1900 Extended PCS 1850 – 1915 1930 – 1995 80 1.4, 3, 5, 10, 15, 20
26 FDD 850 Extended Cellular 814 – 849 859 – 894 45 1.4, 3, 5, 10, 15
27 FDD 800 SMR 807 – 824 852 – 869 45 1.4, 3, 5, 10
28 FDD 700 APT 703 – 748 758 – 803 55 3, 5, 10, 15, 20
29 SDL 700 Lower SMH N/A 717 – 728 N/A 3, 5, 10
30 FDD 2300 WCS 2305 – 2315 2350 – 2360 45 5, 10
31 FDD 450 NMT / LTE 450 452.5 – 457.5 462.5 – 467.5 10 1.4, 3, 5
32 SDL[A 11] 1500 L-Band (EU) 75 N/A 1452 – 1496 N/A 5, 10, 15, 20
33 TDD 2100 IMT 39 1900 – 1920 N/A 5, 10, 15, 20
34 TDD 2100 IMT 2010 – 2025 N/A 5, 10, 15
35 TDD 1900 PCS (UL) 1850 – 1910 N/A 1.4, 3, 5, 10, 15, 20
36 TDD 1900 PCS (DL) 1930 – 1990 N/A 1.4, 3, 5, 10, 15, 20
37 TDD 1900 PCS 1910 – 1930 N/A 5, 10, 15, 20
38 TDD 2600 IMT-E 41 2570 – 2620 N/A 5, 10, 15, 20
39 TDD 1900 DCS–IMT Gap 1880 – 1920 N/A 5, 10, 15, 20
40 TDD 2300 S-Band 2300 – 2400 N/A 5, 10, 15, 20
41 TDD 2500 BRS 2496 – 2690 N/A 5, 10, 15, 20
42 TDD 3500 CBRS (EU, Japan) 3400 – 3600 N/A 5, 10, 15, 20
43 TDD 3700 S-Band 3600 – 3800 N/A 5, 10, 15, 20
44 TDD 700 APT 703 – 803 N/A 3, 5, 10, 15, 20
45 TDD 1500 L-Band (China) 50 1447 – 1467 N/A 5, 10, 15, 20
46 TDD 5200 U-NII 5150 – 5925 N/A 10, 20
47 TDD 5900 U-NII-4 5855 – 5925 N/A 10, 20
48 TDD 3500 CBRS (US) 3550 – 3700 N/A 5, 10, 15, 20
49 TDD 3600 S-Band 48 3550 – 3700 N/A 10, 20
50 TDD 1500 L?Band (EU) 1432 – 1517 N/A 3, 5, 10, 15, 20
51 TDD 1500 Extended L?Band (EU) 1427 – 1432 N/A 3, 5
52 TDD 3300 S-Band 3300 – 3400 N/A 5, 10, 15, 20
65 FDD 2100 Extended IMT 1920 – 2010 2110 – 2200 190 5, 10, 15, 20
66 FDD 1700 Extended AWS (AWS?1–3) 1710 – 1780 2110 – 2200 400 1.4, 3, 5, 10, 15, 20
67 SDL[A 11] 700 EU 700 N/A 738 – 758 N/A 5, 10, 15, 20
68 FDD 700 ME 700 698 – 728 753 – 783 55 5, 10, 15
69 SDL[A 11] 2600 IMT-E N/A 2570 – 2620 N/A 5
70 FDD 2000 AWS?4 1695 – 1710 1995 – 2020 295 – 300 5, 10, 15
71 FDD 600 Digital Dividend (US) 663 – 698 617 – 652 ?46 5, 10, 15, 20
72 FDD 450 PMR (EU) 451 – 456 461 – 466 10 1.4, 3, 5
73 FDD 450 PMR (APT) 450 – 455 460 – 465 10 1.4, 3, 5
74 FDD 1500 Lower L-Band (US) 1427 – 1470 1475 – 1518 48 1.4, 3, 5, 10, 15, 20
75 SDL[A 11] 1500 L-Band (EU) N/A 1432 – 1517 N/A 5, 10, 15 20
76 SDL 1500 Extended L?Band (EU) N/A 1427 – 1432 N/A 5
85 FDD 700 Extended Lower SMH 698 – 716 728 – 746 30 5, 10
252 SDL 5200 U-NII-1 N/A 5150 – 5250 N/A 20
255 SDL 5800 U-NII-3 N/A 5725 – 5850 N/A 20

 

 

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