IoT M2M blog

The home of free hints and tips about wireless IoT / M2M

Embedded GSM antenna

Why paying for an embedded GSM antenna if you can get the antenna for free?

embedded GSM antenna

embedded GSM antenna

The antenna at the picture or a lot of other embedded GSM antennas you will get free of charge. There is no reason to pay for. You just have to spend an area of estimated 800 to 1000 mm² on your PCB. You do not like the published antenna shape and you are looking for an other type of embedded GSM UMTS antenna? Then do not hesitate to ask for your customised version.

In the magic world of embedded GSM antennas everything is cycling around the wavelength named Lambda or better said the quarter of the wavelength = Lambda/4 .

The red coloured part of the picture view is the part of antenna that will radiate at the lower band GSM 850/ 900MHz. A+B+C+D = 79 mm.

The green coloured part of the draft is the area that will radiate at the higher bands like GSM 1800/1900. I+F = 41 mm. The yellow part of the picture is showing the feeding line and the three rectangle black blocks are maybe capacitors or coils for the matching circuit.

The blue, red, green and yellow coloured aeras are cupper on FR4 PCB.

The gap between the branches of the antennas to the blue area is related to the bandwidth of the embedded GSM antenna. The blue part is called ground plane and has to have a size of 3500 mm2 to 4000 mm2. If it is less, then the efficiency of the antenna will be less as well. All lambda/4 GSM antennas has to follow this rules. Test it yourself and compare the size of your phone with the size of the mobile phone of your friend or an 5 years old phone.

Do you have further questions and would like to start the development of your own wireless M2M device right now? We will be glad to share our more than 15 years in GSM and GPS plus 25 years in radio communication with you. Just send an e-mail by using the form here or by e-mail to harald.naumann (at) gsm-modem.de .

8 Comments

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  1. Email to me:
    Thank you very much for your article

    It was very interesting and informative.

    Please, if you’ll have free time please answer my questions.

    On the figure is not clear where is the feed point. Where is the yellow line is attached to the red and green lines?
    HN: Red, green and yellow lines are on the same layer. The copper structure is one and the same.

    Do you have a more detailed picture?
    HN: Yes, I have a more detailed description as PDF file.

    Is the red and the green line is shorted to ground plane on the left?’

    HN: Yes, at left side it it shorted to ground. It is a IFA an inverted F antenna with two rods. The longer structure is for GSM 900 and the short is for 1800 MHz. If you search on Google, then you will find a lot of information about 2400 MHz IFA antennas.

    Is the length of the antenna depends on the thickness of the copper layer and the thickness of the FR-4?
    HN: You are right. FR4 has an Epsilon R of 4,2 in average.

  2. I liked your explanation. You could send me detailed drawings of the structure of this antenna? Thanks

  3. Hi Lucas, just email me (harald.naumann (at) gsm-modem.de ) and I will help with the description of the embedded GSM antenna. Please note that I can help with optimisation of the embedded GSM antenna on your PCB and enclosure within nominal 4 to 8 hours. Customers of mine get a design review and a further review by manufacturer of GSM module free of charge. This will minimise trouble during tuning.

  4. Dear Harald Naumann,

    Thank you very for your good explanation.

    Please give me more details of size :
    A= , B= , C= , D= , I=

    And more explanations of:
    Size of antenna structure: 50mm x 10 mm
    Size of ground plane: 50 mm x 90 mm
    Size of hole PCB: 50 mm x 100 mm
    Or you could give me the antenna drawing .

    Many thanks for your support,
    Regards,
    Hieu Nguyen

  5. Do you have your book in PDF format? What is its cost? What is included? I am in Venezuela and it is hard for me to buy a printed book. Thank you.

  6. Hi Daniel, right now I have a PDF version only and a printed version on paper is planned for end of this year. The printed version I need for local customers and for some universities. Based on consulting contracts and readers of the book, I got feedback and ideas for further content. The book contains mainly content, which is not described in the manuals of the manufacturers of wireless modules or embedded antennas. The simulated GSM IFA antenna is explained in detail, but the basic function of an IFA antenna I repeated not in the book. Therefore I show several external PDF files which will tell the working very well.
    Hi Daniel, right now I have a PDF version only and a printed version on paper is planned for end of this year. The printed version I need for local customers and for some universities. Based on consulting contracts and readers of the book, I got feedback and ideas for further content. The book contains mainly content, which is not described in the manuals of the manufacturers of wireless modules or embedded antennas. The simulated GSM IFA antenna is explained in detail, but the basic function of an IFA antenna I repeated not in the book. Therefore I show several external PDF files which will tell the working very well. Changes of the chapters I mark with green colour and major changes like new chapters I mark with a time stamp. All readers get updates endless. Nevertheless any book can’t have endless pages. It already has 59 pages DIN A5 or 30636 words and is still growing. End of the year I will freeze the book and start with extension which I will call recipes.

    Table of contents (of today)
    1 Why to write the IoT / M2M Cookbook? 5
    2 Fundamental considerations before starting the IoT / M2M project 5
    3 Certifications and approvals 6
    3.1 Examples for Radio approvals in EU and US 6
    3.2 Examples for Radio approvals in US 7
    3.3 Examples for automotive related approvals in Europe 7
    3.4 SAR – Specific Absorption Rate 8
    4 Cellular data communication (GPRS, USSD, SMS, CSD, DTMF) 9
    4.1 Voice communication 9
    4.2 Modem / acoustic coupler / encryption 9
    4.3 DTMF (Dual Tone Multi Frequency) 10
    4.4 GPRS (General Packed Radio Service) 10
    4.5 SMS 10
    4.6 USSD (Unstructured Supplementary Service Data) 11
    4.7 Comparison of power consumption (SMS, USSD and GPRS) 12
    4.8 CSD (Circuit Switched Data) 13
    5 Supply voltage 13
    5.1 Cellular module in power save mode (14.01.2014) 14
    5.2 Internal resistance of batteries and linear voltage transformers 14
    5.3 Switched mode voltage regulator 16
    5.4 Capacitors at power supply and cellular module (14.04.2014) 16
    5.5 Supply voltage for GNSS antenna (14.04.2014) 16
    6 Antennas for IoT / M2M devices 17
    6.1 Monopole and dipole antennas 17
    6.2 Nothing will interfere with your embedded antenna? 17
    6.3 Why the embedded chip or patch antennas are resonant on the frequency? 18
    6.4 How will the ground plane affect your embedded antenna? 18
    6.5 How to connect your embedded antenna with your wireless module? 20
    6.6 How to design an antenna matching circuit? 21
    6.7 Free of charge software to generate a matching circuit automatically 22
    6.8 How to switch between an internal and external cellular or GNSS antenna cheap? 22
    6.9 Which GPS antenna shall be used for a tracking device? 23
    6.10 Which embedded antenna to select for a Bluetooth / GNSS application? 24
    6.11 Dos and don’ts during embedded antenna design 25
    6.12 Example: Embedded PCB antenna inside a vending machine of NeoNumus 26
    6.13 Example: Embedded antennas at Telematic device IN1 of GPSoverIP 28
    7 Simulation of an embedded GSM PCB track antenna 28
    7.1 Definition of the antenna simulation project 28
    7.2 Description of the inverted F antenna 29
    7.3 3D model of the simulation 30
    7.4 Optimization – determination of antenna shape 31
    7.5 Typical requirements of a quad band GSM antenna 31
    7.6 Optimization of the quad band antenna GSM antenna shape 34
    7.7 Directional characteristics of the antenna for two GSM frequencies 35
    7.8 Influence on the antenna characteristics of the housing 37
    7.9 Influence of the ground plane on the antenna characteristics 38
    7.10 Optimisation of the simulated antenna with matching circuit (03.05.2014) 39
    8 Components around the cellular module 39
    8.1 SIM card 39
    8.2 SIM card subscription 40
    8.3 Low ESR capacitor 40
    8.4 ESD protection and shielding (14.04.14) 41
    8.5 Loudspeaker and microphone (14.04.14) 41
    8.6 Firmware update at final PCB 42
    9 Examples for mistakes and errors during M2M development 42
    9.1 Power down reset 42
    9.2 SMS errors 42
    9.3 CSD errors 43
    9.4 IP connection errors 43
    9.5 Analysing of a maximum of design mistakes in one M2M design 44
    9.6 Analysing of mistakes at PCB track antenna for GSM 44
    9.7 Analysing of GSM chip antenna on small ground plane 45
    9.8 Analysing of a Swiss GSM watch 46
    9.9 Analysing of embedded LTE antenna in detail (27.04.2014) 47
    10 Testing your M2M device 48
    10.1 Emulation of TX power peaks 48
    10.2 TX power peaks by cellular module test mode 48
    10.3 TX power peaks by GSM tester 48
    10.4 Testing of the sensitivity 48
    10.5 Testing of the radiated TX power 49
    10.6 Where to get a cheap cellular tester? 49
    10.7 Example of a measurement report by GSM test equipment (26.07.2014) 49
    10.8 Example of a measurement report by GSM test equipment (26.08.2014) 53
    10.9 How to test an UMTS module on foreign band (26.08.2014) 54
    10.10 Test with expensive UMTS tester 54
    10.10.1 Tests without UMTS tester 55
    10.11 Testing the GNSS module (28.08.2014) 55
    10.12 Measurement of the cellular antenna in 3D 56
    10.13 Summary of testing 56
    11 AT Commands 56
    11.1 AT commands during power on your cellular module evaluation kit 56
    11.2 Hello World in GSM – AT commands to send a SMS 58
    11.3 AT commands and logic loops for set up a communication channel 58
    12 Nice tools to make the IoT / M2M development easier (27.04.2014) 58
    13 Thank you 59

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