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This paper presents a four-pole elliptic tunable combline bandpass filter with center frequency and bandwidth control. The filter is built on a Duroid substrate with \varepsilonr=10.2 and h=25~mils, and the tuning is done using packaged Schottky diodes. A frequency range of 1.55–2.1 GHz with a 1-dB bandwidth tuning from 40–120 MHz (2.2–8% fractional bandwidth) is demonstrated. A pair of tunable transmission zeroes are synthesized at both passband edges and significantly improve the filter selectivity. The rejection level at both the lower and upper stopbands is > 50~\ dB and no spurious response exists close to the passband. The measured third-order intermodulation intercept point (TOI) and 1-dB power compression point at midband (1.85 GHz) and a bandwidth of 110 MHz are > 14~dBm and 6 dBm, respectively, and are limited by the Schottky diodes. It is believed that this is the first four-pole combline tunable bandpass filter with an elliptic function response and center frequency and bandwidth control. The application areas are in tunable filters for wireless systems and cognitive radios. [ABSTRACT FROM AUTHOR]

A three-pole microstrip combline filter with a center frequency of 1.75–2.25 GHz and a tunable bandwidth of 70–100 MHz is presented. In this design, an extra transmission zero is created using a non-adjacent resonator coupling, and is placed on the lower side of the passband to improve the filter selectivity. The filter bandwidth is also tuned by controlling the non-adjacent resonator coupling. The measured S-parameters, third-order intercept point and power handling, for different center frequencies and bandwidths, are presented and with good agreement with simulations. This topology is simple to implement and requires only one additional tunable component between the first and third resonator for bandwidth control. [ABSTRACT FROM AUTHOR]

This paper presents a three-pole tunable combline bandpass filter with center frequency, bandwidth, and zero control. The filter is designed on a Duroid substrate with \varepsilonr=10.2 and h=25\ \mil. A frequency range of 1.5–2.2 GHz with a 1-dB bandwidth tuning from 50 to 170 MHz (2.2%–11.2% fractional bandwidth) is achieved. The transmission zero can also be controlled, and a zero location of 1.37–1.64 GHz is demonstrated at center frequency fo of 2.05 GHz. The measured third-order intermodulation intercept point and 1-dB power compression point at midband (1.85 GHz) and a bandwidth of 110 MHz are >15 and 8 dBm, respectively. To our knowledge, this is the first three-pole combline tunable bandpass filter with center frequency, bandwidth, and transmission zero control. [ABSTRACT FROM AUTHOR]

A high-efficiency self-shielded microstrip-fed Yagi-Uda antenna has been developed for 60 GHz communications. The antenna is built on a Teflon substrate (\varepsilonr = 2.2) with a thickness of 10 mils (0.254 mm). A 7-element design results in a measured S 11 of < -10~dB at 56.0 – 66.4 GHz with a gain> 9.5 ~dBi at 58 – 63 GHz. The antenna shows excellent performance in free space and in the presence of metal-planes used for shielding purposes. A parametric study is done with metal plane heights from 2 mm to 11 mm, and the Yagi-Uda antenna results in a gain> 12 ~dBi at 58 – 63 GHz for h = 5 -8~mm. A 60 GHz four-element switched-beam Yagi-Uda array is also presented with top and bottom shielding planes, and allows for 180^\circ angular coverage with < 3~dB amplitude variations. This antenna is ideal for inclusion in complex platforms, such as laptops, for point-to-point communication systems, either as a single element or a switched-beam system. [ABSTRACT FROM AUTHOR]

In this paper, we propose an improved doubly electromagnetic periodic structure (DEPS) and apply it in a power amplifier for harmonic tuning. The DEPS power amplifier shows an improvement of 0.5 dB and 8% in output power and power-added efficiency (PAE), respectively, compared with the conventional EPS power amplifier. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 342–344, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11209 [ABSTRACT FROM AUTHOR]

A response from the author of the article "A Quasi Elliptic Function 1.75?2.25 GHz 3-Pole Bandpass Filter With Bandwidth Control" that was published in the February 2012 issue is presented.