## REFERENCES

[1]
Vanier, J.; Mandache, C.: The passive optically pumped Rb frequency standard: the laser approach. Appl. Phys. B, 87 (4) (2007), 565–593.

[2]
Wynands, R.; Weyers, S.: Atomic fountain clocks. Metrologia, 42 (3) (2005), S64.

[3]
Cutler, L.S.: Fifty years of commercial caesium clocks. Metrologia, 42 (3) (2005), S90.

[4]
Vig, J.R.: Quartz crystal resonators and oscillators for frequency control and timing applications. NASA STI/Recon Technical Report N, 2001.

[5]
Micalizio, S.; Calosso, C.E.; Godone, A.; Levi, F.: Metrological characterization of the pulsed Rb clock with optical detection. Metrologia, 49 (4) (2012), 425.

[6]
Micalizio, S.; Godone, A.; Levi, F.; Calosso, C.: Pulsed optically pumped ^{87}Rb vapor cell frequency standard: a multilevel approach. Phys. Rev. A, 79 (2009), 013403.

[7]
Camparo, J.: The rubidium atomic clock and basic research. Phys. Today, 60 (11) (2007), 33–39.

[8]
Godone, A.; Micalizio, S.; Levi, F.; Calosso, C.: Microwave cavities for vapor cell frequency standards. Rev. Sci. Instrum., 82 (7) (2011), 074703-1–074703-15.

[9]
Pozar, D.M.: Microwave Engineering, 3rd ed., Wiley, Hoboken, NJ, 2005.

[10]
Cameron, R.; Mansour, R.; Kudsia, C.: Microwave Filters for Communication Systems: Fundamentals, Design and Applications, Wiley, Michigan, USA, 2007.

[11]
Vanier, J.; Bernier, L.-G.: On the signal-to-noise ratio and short-term stability of passive rubidium frequency standards. IEEE Trans. Instrum. Meas., IM-30 (4) (1981), 277–282.

[12]
Affolderbach, C.; Du, G.X.; Bandi, T.; Horsley, A.; Treutlein, P.; Mileti, G.: Imaging microwave and DC magnetic fields in a vapor-cell Rb atomic clock. IEEE Trans. Instrum. Meas., 64 (12) (2015), 3629–3637.

[13]
Vanier, J.; Audoin, C.: The Quantum Physics of Atomic Frequency Standards, ser. The Quantum Physics of Atomic Frequency Standards, A. Hilger, Philadelphia, USA, 1989, no. v. 1.

[14]
Stefanucci, C.
et al. : Compact microwave cavity for high performance rubidium frequency standards. Rev. Sci. Instrum., 83 (10) (2012), 104706-1–104706-8.

[15]
Major, F.G.: The Quantum Beat, vol. 1, Springer, New York, USA, 2010.

[16]
Li, S.; Yang, Q.X.; Smith, M.B.: Rf coil optimization: evaluation of b1 field homogeneity using field histograms and finite element calculations. Magn. Reson. Imag., 12 (7) (1994), 1079–1087.

[17]
Froncisz, W.; Hyde, J.S.: The loop-gap resonator: a new microwave lumped circuit ESR sample structure. J. Magn. Reson. (1969), 47 (3) (1982), 515–521.

[18]
Sphicopoulos, T.; Gardiol, F.: Slotted tube cavity – a compact resonator with empty core. IEE Proc. H: Microw. Antennas Propag., 134 (1987), 405–410.

[19]
Chen, H.; Li, J.; Liu, Y.; Gao, L.: A study on the frequency-temperature coefficient of a microwave cavity in a passive hydrogen maser. Metrologia, 49 (6) (2012), 816.

[20]
Bandi, T.; Affolderbach, C.; Stefanucci, C.; Merli, F.; Skrivervik, A.K.; Mileti, G.: Compact high-performance continuous-wave double-resonance rubidium standard with 1.4e-13 tau-1/2 stability. IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 61 (11) (2014), 1769–1778.

[21]
Kobayashi, Y.; Yoshida, S.: Bandpass filters using tm/sub 010/dielectric rod resonators, in 1978 IEEE-MTT-S Int. Microwave Symp. Digest, June 1978, 233–235.

[22]
Feresidis, A.P.; Goussetis, G.; Wang, S.; Vardaxoglou, J.C.: Artificial magnetic conductor surfaces and their application to low-profile high-gain planar antennas. IEEE Trans. Antennas Propag., 53 (1) (2005), 209–215.

[23]
Dancila, D.; Rottenberg, X.; Focant, N.; Tilmans, H.A.C.; De Raedt, W.; Huynen, I.: Compact cavity resonators using high impedance surfaces. Appl. Phys. A, 103 (3) (2011), 799–804.

[24]
Mett, R.R.; Froncisz, W.; Hyde, J.S.: Axially uniform resonant cavity modes for potential use in electron paramagnetic resonance spectroscopy. Rev. Sci. Instrum., 72 (11) (2001), 4188.

[25]
Anderson, J.R.; Mett, R.R.; Hyde, J.S.: Cavities with axially uniform fields for use in electron paramagnetic resonance: II. Free space generalization. Rev. Sci. Instrum., 73 (8) (2002), 3027.

[26]
Hyde, J.S.; Mett, R.R.; Anderson, J.R.: Cavities with axially uniform fields for use in electron paramagnetic resonance. III. Re-entrant geometries. Rev. Sci. Instrum., 73 (11) (2002), 4003.

[27]
Mett, R.R.; Sidabras, J.W.; Hyde, J.S.: Uniform radio frequency fields in loop-gap resonators for EPR spectroscopy. Appl. Magn. Reson., 589 (2007), 573–589.

[28]
Gurman, I.
et al. : Dual frequency cavity resonator for atomic manipulation and spectroscopy, in IEEE Int. Conf. on Microwaves, Communications, Antennas and Electronics Systems, 2009. COMCAS 2009, November 2009, 1–6.

[29]
Pisano, G.; Ade, P.A.R.; Tucker, C.: Experimental realization of an achromatic magnetic mirror based on metamaterials. Appl. Opt., 55 (18) (2016), 4814–4819.

[30]
Hyde, J.S.; Froncisz, W.; Oles, T.: Multipurpose loop-gap resonator. J. Magn. Reson. (1969), 82 (2) (1989), 223–230.

[31]
Ivanov, A.E.; Skrivervik, A.K.; Affolderbach, C.; Mileti, G.: Compact microwave cavity with increased magnetic field homogeneity, in 2016 10th Eur. Conf. on Antennas and Propagation (EuCAP), April 2016, 1–5.