**8. Comparison**

It is important to understand both the advantages and disadvantages of orthogonal fluxgates when we have to select a magnetic sensor for a specific application. Depending on the particular requirements of the measurement system, the best solution can be a parallel or an orthogonal fluxgate. Here we give a list of both advantages and disadvantages of orthogonal fluxgates in order to help the user in choosing the best sensor for his/her purposes.

Advantages of orthogonal fluxgates


Disadvantages of orthogonal fluxgates


be around zero magnetic field and the output characteristic will be determined by the linear

This method, however, cannot be used for coil-less fluxgates, since it has not a pick-up coil available for the generation of a compensating field (and if we add a compensation coil the

Therefore, the linearity of the coil-less fluxgate is an extremely important parameter, because the sensor will be used in an open loop mode. Fortunately, the coil-less fluxgate has a large linear range. In (Butta et al., 2010c) it is shown that a coil-less fluxgate with ±0.5% of full-scale non-linearity error in a ±50 µT measurement range. The non-linearity error is reduced to ±0.2% of full scale if we consider a ± 40 µT range. These values are comparable to the non-linearity of

The high linearity of coil-less fluxgates comes from the working mechanism of the sensor, which is simply based on linear shifts of the circumferential BH loop. Non-linearity might be due to the non-uniformity of the helical anisotropy angle along its length. Further improvements of the manufacturing process can help make the anisotropy more uniform

The noise of a coil-less fluxgate is rather high. For instance, in (Butta et al., 2010c) a coil-less fluxgate is presented which shows 3 nT/√Hz at 1Hz noise. This is much higher than the noise of other orthogonal fluxgates, operated in a fundamental mode, mainly because of low sensitivity. The noise of coil-less fluxgates manufactured with Co-base magnetic wires, which have larger sensitivity, has still not been reported. It can be expected that further improvements of the sensitivity of coil-less fluxgates will contribute to decrease the noise.

It is important to understand both the advantages and disadvantages of orthogonal fluxgates when we have to select a magnetic sensor for a specific application. Depending on the particular requirements of the measurement system, the best solution can be a parallel or an orthogonal fluxgate. Here we give a list of both advantages and disadvantages of orthogonal



fluxgates in order to help the user in choosing the best sensor for his/her purposes.


parallel fluxgate cores are often saturated with several hundreds of mA).


non-compensated parallel fluxgates (Kubik et al., 2009; Janosek & Ripka, 2009).

characteristic of the coil.

sensor would not be coil-less anymore).

and improve the linearity of the sensor.

Advantages of orthogonal fluxgates

Disadvantages of orthogonal fluxgates - higher noise than parallel fluxgates;


**7.5 Noise** 

**8. Comparison** 


The following table summarizes several orthogonal fluxgates reported in the literature with their features and obtained performance. The proper choice for structure and operative parameters of orthogonal fluxgates can be made based on the application requirements and available performances summarized here.


