and the reflection losses are better than 12 dB throughout the pass band for both cases.In addition, a two-cell CRLH filter is designed at a center frequency of 1.8 GHz and a fractional bandwidth of 110% following the procedure expanded in [10]. The design values of the CRLH unit cell are C R ¼ 0.5 pF, L R ¼ 1.6 nH, C L ¼ 2.2 pF, and L L ¼ 4.3 nH. This gives a À3 dB lower cutoff of f 1 ¼ 0.8 GHz and an upper cutoff f 2 ¼ 2.8 GHz. The circuit was implemented using standard surface mount devices (SMD).To implement the notch filter, the ENZ tunnel is connected to the CRLH filter as shown in Figure 5(b). The CRLH filter along the tunnel structure is simulated using [8]. Figure 7 shows the simulated and experimental S 21 and S 11 responses. The simulated notch frequency is read at 1.85 GHz with a reflection loss of about 26 dB and an insertion loss of 1.3 dB. For the experimental response the return loss is 18 dB at the center frequency (1.94 GHz) and an insertion loss of 2 dB is recorded. The experimental 3 dB pass band is 2.14 GHz (from 1.15 to 3.29 GHz). There is a slight frequency shift of 0.2 GHz to lower frequencies in the experiment compared with the simulation. This frequency shift is thought to be because of parasitic effects of the SMD components, the effects of the vias to ground and the mismatch between the microstrip line width and the width of the SMD components. However, good agreement is observed between simulation and experiment. CONCLUSIONSA miniaturized HM substrate integrated ENZ tunnel has been demonstrated. It was shown that this structure allows only one frequency to tunnel through because of the static-like behavior when epsilon is near zero. Subsequently, the tunnel was connected to a CRLH filter in a decoupling mode to reject unwanted frequencies. Good agreement is seen between experimental and simulated results. ABSTRACT: In this study, a dielectric corrugated antenna, as being a feed horn antenna of the reflector antenna for satellite communication applications, is analyzed. The structure consists of a conical dielectric corrugated antenna terminated with a conductor hyperbolic (convex) plate. The antenna system provides a Gaussian beam within wide frequency bandwidth with its dielectric structure. The antenna is simulated and tested for its return loss and radiation performances, and the satisfactory results are obtained for C band satellite communication applications.

In the microwave band, substrate integrated waveguide (SIW) couplers take the advantages of low profile, low insertion loss, low interference etc., but suffer from the big size. In this letter, a novel half mode substrate integrated waveguide (HMSIW) 3-dB coupler is proposed, which keeps the good performance of the SIW coupler with nearly a half reduction in size. Simulated results are in agreement with the measured data.Index Terms-Coupler, half mode substrate integrated waveguide (HMSIW), substrate integrated waveguide (SIW).

Abstract-The propagation properties of the half-mode substrate integrated waveguide (HMSIW) are studied theoretically and experimentally in this paper. Two equivalent models of the HMSIW are introduced. With the first model, equations are derived to approximate the field distribution inside and outside the HMSIW. Using the second model, an approximate closed-form expression is deduced for calculating the equivalent width of an HMSIW that takes into account the effect of the fringing fields. The obtained design formulas are validated by simulations and experiments. Furthermore, the attenuation characteristics of the HMSIW are studied using the multiline method in the frequency range of 20-60 GHz. A numerical investigation is carried out to distinguish between the contributions of the conductive, dielectric, and radiation losses. As a validation, the measured attenuation constant of a fabricated HMSIW prototype is presented and compared with that of a microstrip (MS) line and a substrate integrated waveguide (SIW). The SIW is designed with the same cutoff frequency and fabricated on the same substrate as the HMSIW. The experimental results show that the HMSIW can be less lossy than the MS line and the SIW at frequencies above 40 GHz.Index Terms-Half-mode substrate integrated waveguide (HMSIW), propagation properties.

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