HA.31.A

RF Antenna, Helical, 902 MHz to 928 MHz, Linear, SMD, 2.04 dBi

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Manufacturer: TAOGLAS
Product type:
Gain: 2.04dBi
SVHC: To Be Advised
VSWR: -
Input Power: -
Antenna Type: Helical
Frequency Max: 928MHz
Frequency Min: 902MHz
Product Range: -
Input Impedance: 50ohm
Antenna Mounting: SMD
Antenna Polarisation: Linear

Delivery and price
Units per pack	500
Price	0.497 €
Current stock	10+
Lead time	30 days

Datasheet

## **Specification** 

## **Part No.** : **HA.31.A** 

## **Description** 

- : 915MHz 2dBi Embedded Helical Monopole Antenna 

## **Features** 

- : Quarter wave-length Monopole Helical Antenna 915MHz ISM Band 2dBi peak gain and 68% efficiency Direct mounted on board design Mechanically sturdy in a compact size Dimensions: 10.7mm, Ø10.2mm RoHS and Reach compliant 

DSP-15-8- SPE-16-8-017-E     Page **1** of **24** 

## **1. Introduction** 

The HA.31.A is an ISM 915MHz quarter wave-length monopole antenna. This helical coil antenna is perfect for your smart meter, smart security system, remote asset monitoring, and other wireless communication devices. 

The helical coil antenna has a 2dBi Peak gain and a 68% efficiency at 915MHz on a 126.8 x 80.1mm ground plane with matching components (orthogonally mounted to ground plane, see HAD.B.31 performance). 

Made of copper alloy, the helical coil is mechanically sturdy, with a wide-bandwidth. It can be easily mounted on the surface of your device main board by soldering. The antenna must be connected to a ground-plane to radiate efficiently. 

DSP-15-8- SPE-16-8-017-E     Page **2** of **24** 

Taoglas provides HAD.A.31 and HAD.B.31 evaluation boards to show performance when two antennas are parallel mounted or orthogonally mounted to the ground plane. Small embedded antennas can easily detune and/or have reduced efficiency in different device environments. Taoglas provides matching, and other custom tuning, design and support services, subject to MOQ and NRE. For further information on how to integrate this antenna into your device please contact your regional Taoglas customer support team. 

DSP-15-8- SPE-16-8-017-E     Page **3** of **24** 

## **2. Specification** 

|ELECTRICAL<br>~~a~~|ELECTRICAL<br>~~a~~|ELECTRICAL<br>~~a~~|ELECTRICAL<br>~~a~~|ELECTRICAL<br>~~a~~|ELECTRICAL<br>~~a~~|ELECTRICAL<br>~~a~~|
|---|---|---|---|---|---|---|
|Application Bands<br>~~a~~|ISM 915MHz<br>~~a~~||||||
|Mounting Direction|HAD.A.31|||HAD.B.31|||
|Frequency (MHz)<br>Return Loss (dB)<br>Peak Gain (dBi)|902<br>915<br>928<br>902<br>915<br>928<br><-10<br>0.41<br>0.05<br>-0.74<br>1.89<br>2.09<br>2.04||||||
|Average Gain (dBi)|-3.14|-3.30|-4.05|-1.74|-1.61|-1.65|
|Efficiency (%)<br>Polarization|48.51<br>46.73<br>39.28<br>66.95<br>68.94<br>68.37<br>Linear||||||
|Impedance|50 ohms||||||
|MECHANICAL<br>~~a~~|||||||
|Helical Coil Dimension (mm)|L: 10.7mm, Ø10.2mm||||||
|Weight (g)|0.7||||||
|ENVIRONMENTAL<br>Operation Temperature<br>-40°C to 85°C<br>~~a~~|||||||
|Humidity|Non-condensing 65°C 95% RH||||||



DSP-15-8- SPE-16-8-017-E     Page **4** of **24** 

## **3. Antenna Characteristics** 

## **3.1 Return Loss** 

## **3.2 Efficiency** 

DSP-15-8- SPE-16-8-017-E     Page **5** of **24** 

## **3.3 Average Gain** 

## **3.4 Peak Gain** 

DSP-15-8- SPE-16-8-017-E     Page **6** of **24** 

## **4. Antenna Radiation Pattern** 

## **4.1. Measurement Setup** 

The HA.31 antenna is tested on HAD.A.31 and HAD.B.31in a CTIA certified ETS-Lindgren Anechoic Chamber. The test setup is shown below. 

DSP-15-8- SPE-16-8-017-E     Page **7** of **24** 

## **4.2. 2D Radiation Pattern** 

- **On HAD.A.31** 

**==> picture [53 x 9] intentionally omitted <==**

**----- Start of picture text -----**<br>
XY Plane<br>**----- End of picture text -----**<br>


**==> picture [142 x 135] intentionally omitted <==**

**----- Start of picture text -----**<br>
X<br>0<br>30<br>=<br>60<br>|<br>Y<br>**----- End of picture text -----**<br>


**==> picture [307 x 141] intentionally omitted <==**

**----- Start of picture text -----**<br>
XZ Plane<br>Z<br>0<br>5<br>330 30<br>300 60<br>270 90 X<br>**----- End of picture text -----**<br>


DSP-15-8- SPE-16-8-017-E     Page **8** of **24** 

YZ Plane 

Z 

**==> picture [12 x 9] intentionally omitted <==**

**----- Start of picture text -----**<br>
Y<br>**----- End of picture text -----**<br>


## **On HAD.B.21** 

XY Plane 

**==> picture [13 x 9] intentionally omitted <==**

**----- Start of picture text -----**<br>
X<br>**----- End of picture text -----**<br>


**==> picture [12 x 9] intentionally omitted <==**

**----- Start of picture text -----**<br>
Y<br>**----- End of picture text -----**<br>


DSP-15-8- SPE-16-8-017-E     Page **9** of **24** 

## XZ Plane 

**==> picture [143 x 130] intentionally omitted <==**

**----- Start of picture text -----**<br>
Z<br>0<br>30<br>X<br>**----- End of picture text -----**<br>


## YZ Plane 

**==> picture [142 x 133] intentionally omitted <==**

**----- Start of picture text -----**<br>
Z<br>0<br>30<br>60<br>90 Y<br>**----- End of picture text -----**<br>


DSP-15-8- SPE-16-8-017-E     Page **10** of **24** 

## **4.3. 3D Radiation Pattern** 

## - **On HAD.A.31** 

## @915MHz 

## - **On HAD.B.31** 

## @915MHz 

DSP-15-8- SPE-16-8-017-E     Page **11** of **24** 

## **5. Mechanical Drawing (Unit: mm)** 

## **5.1 HA.31.A Antenna** 

## **PCB Footprint** 

DSP-15-8- SPE-16-8-017-E     Page **12** of **24** 

## **5.2 HAD.A.31 Evaluation Board** 

Unit: mm 

DSP-15-8- SPE-16-8-017-E     Page **13** of **24** 

**5.3 HAD.B.31 Evaluation Board** Unit: mm | A DSP-15-8- SPE-16-8-017-E     Page **14** of **24** 

## **6. Packaging** 

## **6.1. HA.31.A Antenna** 

DSP-15-8- SPE-16-8-017-E     Page **15** of **24** 

## **6.2. HAD.A.31** 

**==> picture [57 x 72] intentionally omitted <==**

**----- Start of picture text -----**<br>
EPE Foam<br>PE Bag<br>**----- End of picture text -----**<br>


DSP-15-8- SPE-16-8-017-E     Page **16** of **24** 

## **6.3. HAD.B.31** 

**==> picture [64 x 77] intentionally omitted <==**

**----- Start of picture text -----**<br>
EPE Foam<br>PE Bag<br>**----- End of picture text -----**<br>


DSP-15-8- SPE-16-8-017-E     Page **17** of **24** 

## **7. Antenna Application Note** 

## **7.1 Matching Circuit for Different Ground Plane Variation 7.1.1 HAD.A.31 EVB Board** 

|HAD.A.31<br>~~a~~|Ceramic 4<br>~~a~~|Ceramic 5<br>~~a~~<br>~~a~~|Ceramic 6<br>~~a~~|
|---|---|---|---|
|160mm|0 ohm|3pF<br>~~a~~|1.5pF|
|150mm|0 ohm|3.3pF|1.5pF|
|140mm|0 ohm|3.6pF|1.5pF|
|130mm|0 ohm|3.9pF|1.5pF|
|120mm|0 ohm|3.9pF|1.5pF|
|110mm|0 ohm|3.9pF|1.5pF|
|100mm|0.5pF|2pF|1.5pF|
|90mm|0.5pF|1pF|1.5pF|
|80mm|0.5pF|open|5.1nH|
|70mm|0.75pF|open|3.9pF|
|60mm|0.75pF|open|2.7pF|
|50mm|1pF|open|1pF|



## **7.1.1 HAD.B.31 EVB Board** 

|HAD.B.31<br>~~a~~|Ceramic 4|Ceramic 5|Ceramic 6|
|---|---|---|---|
|160mm<br>~~a~~|0 ohm|open|2.2pF|
|150mm|0 ohm|open|2.7pF|
|140mm|0 ohm|open|3pF|
|130mm|0 ohm|open|3pF|
|120mm|0 ohm|open|3pF|
|110mm|0 ohm|open|3.9pF|
|100mm|3.3pF|open|0 ohm|
|90mm|4.7pF|open|0 ohm|



DSP-15-8- SPE-16-8-017-E     Page **18** of **24** 

## **7.2 Return Loss** 

## **7.2.1 HAD.A.31 EVB Board (Different Ground Lengths)** 

## **7.2.2 HAD.B.31 EVB Board (Different Ground Lengths)** 

DSP-15-8- SPE-16-8-017-E     Page **19** of **24** 

## **7.3 Efficiency** 

## **7.3.1 HAD.A.31 EVB Board (Different Ground Lengths)** 

**7.3.2 HAD.B.31 EVB Board (Different Ground Lengths)** 

DSP-15-8- SPE-16-8-017-E     Page **20** of **24** 

## **7.4 Average Gain 7.4.1 HAD.A.31 EVB Board (Different Ground Lengths)** 

## **7.4.2 HAD.B.31 EVB Board (Different Ground Lengths)** 

DSP-15-8- SPE-16-8-017-E     Page **21** of **24** 

## **7.5 Peak Gain** 

## **7.5.1 HAD.A.31 EVB Board (Different Ground Lengths)** 

## **7.5.2 HAD.B.31 EVB Board (Different Ground Lengths)** 

DSP-15-8- SPE-16-8-017-E     Page **22** of **24** 

## **7.6 Antenna Performance Table** 

|ELECTRICAL<br>~~eee~~|ELECTRICAL<br>~~eee~~|ELECTRICAL<br>~~eee~~|ELECTRICAL<br>~~eee~~|ELECTRICAL<br>~~eee~~|ELECTRICAL<br>~~eee~~|ELECTRICAL<br>~~eee~~|
|---|---|---|---|---|---|---|
|Application Bands<br>~~eee~~|ISM 915MHz<br>~~eee~~||||||
|Mounting Direction|HAD.A.31|||HAD.B.31|||
|Frequency (MHz)|902|915|928|902|915|928|
|Efficiency|||||||
|Ground plane length 160mm|50.92|47.74|35.70|54.59|57.56|56.01|
|Ground plane length 150mm|52.62|49.34|38.06|57.57|58.93|56.60|
|Ground plane length 140mm|51.00|47.03|36.57|63.01|60.90|54.24|
|Ground plane length 130mm|50.09|48.24|39.18|65.03|60.52|51.18|
|Ground plane length 120mm|48.20|45.61|36.69|63.62|58.40|48.61|
|Ground plane length 110mm|46.34|44.42|36.39|61.72|55.90|46.48|
|Ground plane length 100mm|48.16|47.19|39.63|56.23|49.34|39.48|
|Ground plane length 90mm|47.83|46.16|38.14|53.94|45.51|34.89|
|Ground plane length 80mm|45.88|46.00|35.12|X|X|X|
|Ground plane length 70mm|44.96|41.97|29.04|X|X|X|
|Ground plane length 60mm|41.46|43.03|27.19|X|X|X|
|Ground plane length 50mm|35.34|36.39|18.52|X|X|X|
|Average Gain(dBi)|||||||
|Ground plane length 160mm|-2.93|-3.21|-4.47|-2.62|-2.40|-2.51|
|Ground plane length 150mm|-2.78|-3.07|-4.19|-2.39|-2.30|-2.47|
|Ground plane length 140mm|-2.92|-3.28|-4.36|-2.00|-2.15|-2.65|
|Ground plane length 130mm|-3.02|-3.17|-4.06|-1.86|-2.18|-2.90|
|Ground plane length 120mm|-3.16|-3.41|-4.35|-1.96|-2.34|-3.13|
|Ground plane length 110mm|-3.34|-3.52|-4.38|-2.09|-2.53|-3.32|
|Ground plane length 100mm|-3.17|-3.26|-4.02|-2.49|-3.07|-4.03|
|Ground plane length 90mm|-3.20|-3.36|-4.18|-2.68|-0.83|-4.57|
|Ground plane length 80mm|-3.38|-3.37|-4.54|X|X|X|
|Ground plane length 70mm|-3.47|-3.77|-5.37|X|X|X|
|Ground plane length 60mm|-3.82|-3.66|-5.65|X|X|X|
|Ground plane length 50mm|-4.51|-4.39|-7.32|X|X|X|



DSP-15-8- SPE-16-8-017-E     Page **23** of **24** 

|Peak Gain(dBi)|Peak Gain(dBi)|Peak Gain(dBi)|Peak Gain(dBi)|Peak Gain(dBi)|Peak Gain(dBi)|Peak Gain(dBi)|
|---|---|---|---|---|---|---|
|Ground plane length 160mm|1.37|1.13|-0.19|0.62|0.87|0.74|
|Ground plane length 150mm|1.33|1.02|-0.18|0.62|0.79|0.59|
|Ground plane length 140mm|0.94|0.58|-0.42|0.99|0.90|0.40|
|Ground plane length 130mm|0.75|0.67|-0.12|0.89|0.66|-0.02|
|Ground plane length 120mm|0.45|0.29|-0.54|0.67|0.37|-0.41|
|Ground plane length 110mm|0.15|-0.04|-0.78|0.42|0.05|-0.72|
|Ground plane length 100mm|-0.29|-0.40|-0.97|-0.15|-0.66|-1.60|
|Ground plane length 90mm|-0.26|-0.64|-1.64|-0.15|-0.83|-1.92|
|Ground plane length 80mm|-0.80|-0.77|-1.91|X|X|X|
|Ground plane length 70mm|-0.94|-1.27|-2.80|X|X|X|
|Ground plane length 60mm|-1.09|-0.96|-2.87|X|X|X|
|Ground plane length 50mm|-1.77|-1.65|-4.56|X|X|X|



Taoglas makes no warranties based on the accuracy or completeness of the contents of this document and reserves the right to make changes to specifications and product descriptions at any time. Taoglas reserves all rights to this document and the information contained herein. 

Reproduction, use or disclosure to third parties without express permission is strictly prohibited. 

> © Taoglas 

DSP-15-8- SPE-16-8-017-E     Page **24** of **24**

Updated at June 9, 2026

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