normal incidence, the measured resonant frequency in the Xband appears at 8.2 and 8.9 GHz. The difference between the measured and simulated results for the K-band can be considered as cable losses, and the gap between the DFSS with the infinite arrays for computer simulation, and the DFSS with finite arrays for measurement. However, in Figure 12, it can be clearly seen that the measured and simulated results are in good agreement, and can be accepted. CONCLUSIONIn this article, to obtain angle and polarization insensitivities and broad bandwidth, a DFSS is proposed, composed of ring patch elements of four different sizes. To enlarge the bandwidth, and to eliminate the interruptions of the transmission peaks, the thickness of foam layer between the FSS layers is adjusted. The proposed DFSS reflects the X-and K-band signals, while transmitting through the C-and Ku-band signals. It is interesting to note that the resonances for X-and K-bands are stable, about variations of incident angle and thickness of the foam. To prove verification of the proposed DFSS, the proposed DFSS is fabricated and measured. The measured transmission coefficients for the proposed DFSS are compared with the simulated ones, and the measured and simulated results are in good agreement. ABSTRACT: A Q-band bidirectional transceiver has been designed and fabricated for millimeter-wave CMOS phase array systems. The proposed design replaces several switches previously required for a bidirectional approach with a compact double-pole double-throw switch. Phase shifting is performed in 90 step using a high-pass/low-pass structure, and the transceiver demonstrates a highly linear phase response. Over the frequency of 35 to 40 GHz, the measured root-mean-square phase error is <5.5 and <12.1 for transmitter and receiver paths, respectively. Key words: CMOS; millimetermillimete-wave; phase array; phase shifter; switch INTRODUCTIONA phase array transceiver requires separate receive (Rx) and transmit (Tx) channels. The size of the phase array system can be reduced significantly by sharing a passive phase shifter for Tx and Rx operation [1]. One disadvantage of the conventional bidirectional approach is the additional switches required at the Tx and Rx outputs. This article discusses the phase and gain response achieved using a bidirectional two-bit transceiver for Q-band phase array system. Several switches required for bidirectional function are replaced with a new double-pole doublethrow (DPDT) switch. Because the size of DPDT switch is very small, the proposed approach allows a simple and compact realization of the phase array transceiver. Furthermore, good isolation of the new approach achieves a good phase response, where root-mean-square (rms) phase error is <5.5 and < 12.1 for transmitter and receiver paths, respectively, over the broad bandwidth of 35 to 40 GHz. SYSTEM AND CIRCUIT DESIGNA schematic for the bidirectional transceiver is shown in Figure 1. The phase shifter uses a high-pass/low-pass configuration which is suitable for dense phase...
In this paper a newly designed internally-coupled asymmetric stepped-impedance resonator (SIR) bandpass filter (BPF) is proposed. The asymmetric SIR structure not only can effectively reduce the circuit size but also can provide two flexibly tunable transmission zeros near the lower and upper passband edges. The first transmission zero is due to the series resonance of the quarter-wavelength open stepped-impedance stub, and the second one is produced by anti-parallel coupling between adjacent SIRs. The proposed BPF was fabricated and simulated using the commercial software HFSS, and agreement between the measured and simulated results was observed. A 0.9-dB insertion loss and a shape factor of 3.6 were achieved in the passband, thus indicating that the proposed filter structure is of practical value.
A balanced band‐notched ultra‐wideband (UWB) filtering slot antenna with high gain is proposed in this article. The high gain is achieved by deploying two identical open‐ended T‐shaped slot radiators in a back‐to‐back fashion. These two slot radiators are fed by differential‐mode (DM) signals output from a balanced band‐notched UWB bandpass filter (BPF) constructed using a stepped‐impedance one‐wavelength (1λ) slotline resonator. The DM notched band for blocking the 5‐GHz WLAN band signals is generated by symmetrically placing a pair of microstrip resonators and a pair of slotline resonators, both being half‐wavelength long, on the two sides of the 1λ slotline resonator. Measured and simulated DM return loss responses agree quite well. The common‐mode (CM) response is excellent with a measured CM return loss of below 0.54 dB in 1‐12 GHz. As compared with its single‐ported standalone slot antenna counterpart, the proposed balanced filtering slot antenna exhibits 2‐dB‐higher measured peak realized gains at, if not all, most frequencies in the notch‐band‐excluded passband.
This article proposes the design of a three-layered balanced circularly polarized (CP) antenna using two tightly stacked conventional single-ended CP slot antennas. With a 1808 delay line inserted into one of the two feeding microstrip lines that form the balanced feedline, differential-mode (DM) input signals can excite CP radiation in the broadside directions with a measured (simulated) axial ratio of as low as 1.3 (0.86) dB. Common-mode (CM) input signals can be well rejected with a measured (simulated) CM return loss of <0.4 (0.5) dB in the DM impedance band. In addition, only a very small proportion of the CM (DM) input signal is converted into a DM (CM) reflected one. These nice properties of the possibly first reported balanced CP antenna were all achieved without placing before the radiation element a CM-suppression filter. K E Y W O R D Sbalanced antenna, circular polarization, common-mode suppression, differential-mode performance
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