Design of a Microstrip Balanced Mixer for Satellite Communication

Abstract

Abstract-The design and measured results of a compact, low cost, low conversion loss microstrip single balanced Schottky diodes mixer is proposed. This mixer is designed for Ka-band satellite transponder simulator to convert the 30 GHz radio-frequency (RF) signal down to the 20 GHz intermediate-frequency (IF) signal with 9.8 GHz local oscillator (LO) frequency. This design takes full advantage of the frequency relationship of the RF, IF and LO, which is 3 : 2 : 1. A microstrip rat-race ring is designed at the LO frequency, which also functions as a 180-degree hybrid coupler at the RF frequency by its intrinsic multi-band characteristic. The amplitude and phase balance at both LO and RF frequency are analyzed, which guarantee the stateof-art performance of this single balanced mixer. The multi-function open/short stubs and a lowpass filter (LPF) with bonding wires across the rat-race ring are optimized to realize this low conversion loss mixer. The measured results show that the conversion loss is less than 9 dB at the IF frequency from 20.0 to 21.6 GHz, and the power of the second harmonic of LO is −45 dBm with +6.5 dBm LO drive power. The 3rd order inter-modulation products (IMD3) could be lower than −50 dBc with LO power higher than +7.8 dBm at the input RF power of −15 dBm.

New Non-Linear Approach for the Evaluation of the Linearity of High Gain Harmonic Self Oscillating Mixers

“…In order to analyze the linearity of the HSOM working as a mixer, the two figures of merit which are commonly used to characterize conventional amplifiers [8-10, 26, 27], and mixers [13,15,17,28], namely, the 1 dB compression point and the third order interception point (IP3), will be calculated. In addition, an in-depth study of the influence of the harmonic content and the operating regime of the circuit on the linearity of the mixing operation will be performed.…”

“…As in any amplifier [8][9][10], mixer [11][12][13][14][15][16][17], or active antenna with mixing capabilities [18], noise behavior [11,12] and IF signal distortion [13,18] are key factors that must be rigorously analyzed and minimized. In this work, it will be shown that the figures of merit which are traditionally used to analyze the linearity of conventional mixers cannot be directly applied to an autonomous circuit like the HSOM, because of the influence of the input RF signal power on the parameters of the self-oscillating signal.…”

An Improved Wideband 180-Degree Hybrid Applied to Balanced Mixer

“…In cross-bar multipliers, the cross-bar balanced architecture with a pair of balanced diodes physically locates inside either the input waveguide [5][6][7] or the output waveguide [8]. However, the design of the cross-bar hybrid relies on the cross-bar structure with a pair of balanced diodes, which cannot be pre-designed as a simplex hybrid like the rat-race hybrid or the others [9,10].…”

A New Scheme for the Design of Balanced Frequency Tripler With Schottky Diodes

“…Millimeter-wave and submillimeter-wave frequency multipliers [1][2][3][4][5][6] and mixers [7][8][9][10][11][12][13][14] based on planar Schottky diodes are widely used for atmosphere and space detection. The multipliers are usually driven by an oscillator [15][16][17][18] or a phase-locked millimeter-wave source.…”