## 1 Introduction  
A CR is defined as a resistance standard with a calculable frequency dependence [1; 2; 3]. It has a known geometry that allows it to be modeled as a transmission line. Therefore, an equation describing the change of the resistance with the frequency can be determined. There are certain types of CR geometries, such as coaxial [1], bifilar [2], quadrifilar [2], and octofilar [3], whose main element consists of a thin NiCr alloy wire, configured as 4-terminal pair standards [4], and with appropriate heat treatment, it is possible to decrease its Temperature Coefficient (TC) below \(1\,\upmu\Omega/\Omega/^{\circ}\)C [5]. The CR plays an essential role in the Farad traceability chain to the Quantum Hall Resistance (QHR) [6]. Through a DC resistance calibration using the QHR as a reference standard that only depends on fundamental constants, the CR is employed as a reference at frequencies of 1592 or 1542 Hz. The \(100\) k\(\Omega\) resistors can then be used in a quadrature bridge to determine the values of the standard capacitors [6]. Since with the CRs, the frequency dependence of impedance standards with traceability to the QHR can be measured, they are used as references for high-accuracy electrical measurement systems [7; 8; 9]. Applications with medical and technologic impact involve high-accuracy impedance measurements, such as electrical characterization of tissue [10; 11], cell detection [12], supercapacitors developments [13], impedance matching in wireless power transfer systems [14], voltage-controlled inverters for electrical grids [15], and characterization of lead-acid batteries [16; 17], only to cite a few examples. To ensure the certainty of the results of environmental research, like solar cell characterization [18], toxicity measurements of nanoparticles [19], or Nitrogen fertilizer monitoring in plants [20], the traceability to fundamental constants of their impedance measurements needs to be fulfilled. If the equipment used in the aforementioned applications do not realize accurate measurements, the implications could be to make wrong decisions, such as apply an excess of fertilizer to plants, which contaminate the soil and the disposable water to humans [21]. Likewise, the equipment that measures power factors implies traceability to impedance standards, therefore, having high accuracy measurement of power factors means to adopt better strategies to increase the efficiency of electrical energy use, which has a direct ambient impact [22]. The frequency performances of CR type coaxial, bifilar, quadrifilar, and octofilar resistors have been evaluated through international comparison. The results indicate that any of those geometries achieve the expected frequency behavior [23]. Nevertheless, their frequency dependence needs to be assessed to ensure no flaws during their construction [24]. Nowadays, at the Centro Nacional de Metrologia (CENAM) in Mexico, the capacitance measurements have traceability to the QHR reproduced at the Bureau International des Poids et Mesures (BIPM) in Paris, France. A set of CRs was developed to form part of the CENAM QHR--Farad traceability chain; one with a bifilar geometry of 1 k\(\Omega\), another with a quadrifilar geometry of 1 k\(\Omega\), and two with octofilar geometry of 10 k\(\Omega\). Figure 1 exhibits the CRs exploded views for the three types of geometries. The 10 k\(\Omega\) CR will be used as a reference to calibrate 100 k\(\Omega\) resistors at 1592 Hz. Then, they will be part of a quadrature bridge to determine the value of 1 nF capacitance standards [25]. Additionally, the set of CRs will be utilized as standards to improve the frequency impedance measurement capabilities. During 2017, a 1 k\(\Omega\) bifilar CR and a 10 k\(\Omega\) octofilar CRs traveled to the Federal Institute of Metrology (METAS) in Switzerland. A set of 1:1 and 10:1 ratio measurements was performed using as a reference a METAS 1 k\(\Omega\) coaxial CR.