Radio Microphone Antenna System with Variable Slope Compensator
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Radio microphones face challenges in achieving frequency-independent transmission without degrading the intercept performance due to varying cable lengths and qualities, which require non-constant and variable amplification, affecting noise factor and intercept.
Innovation Solution
A variable slope compensator in series with an attenuator, using high pass filters with fixed resistances and MEMS switches for precise control, allowing for digital adjustment of slope and attenuator settings to match specific cable types, ensuring optimal noise factor to intercept ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable amplification is used to compensate cable attenuation, then frequency-independent transmission is improved, but intercept performance deteriorates
Solution Approach 1:
The compensation function is divided into two independent segments: a fixed attenuator that provides constant attenuation regardless of frequency, and a variable slope compensator that adjusts frequency-dependent attenuation. This segmentation allows each component to be optimized for its specific function, with the fixed attenuator maintaining intercept performance and the slope compensator enabling frequency-independent transmission.
Solution Approach 2:
Different parts of the frequency spectrum are treated differently through the slope compensator, which applies varying attenuation levels at different frequencies based on cable characteristics. This local quality adjustment compensates for frequency-dependent cable attenuation without requiring variable amplification across the entire system.
2Ease of operation
If controllable attenuators are used to compensate cable attenuation, then amplification control is improved, but noise factor and intercept deteriorate
Solution Approach 1:
The frequency-dependent compensation function is extracted from the main signal path and implemented separately through the slope compensator. This allows the main amplifier to operate at fixed, optimized settings for intercept and noise factor, while the extracted slope compensation function handles frequency-dependent attenuation compensation without interfering with the amplifier's optimal operating point.
3Adaptability or versatility
If amplifier gain is made variable to match cable attenuation, then transmission compensation is improved, but noise factor increases
Solution Approach 1:
The system dynamically adjusts the slope compensator settings based on cable length and type, but the main amplifier operates at a fixed, optimized gain. This dynamic adjustment is localized to the slope compensator which modifies frequency-dependent attenuation characteristics without changing the overall amplifier gain, thereby maintaining optimal noise factor while achieving transmission compensation.
Data Source
Figure 1~2
Figure 3~8
Figure 4
AI summary
The invention concerns an antenna system of a radio microphone, containing an antenna path starting at an In port (2), and ending at an Out port (6), with an amplifier (3) and a RF cable (5). In order to compensate for various cable attenuations, an attenuator (4) is provided in series with a variable slope compensator (7) between the amplifier (3) and the RF cable (5). In order to avoid the negative effect on large signal behavior of variable slope compensators according to the prior art, FETs or pin diodes or similar "micro-switches" are used for switching of the resistances, but only as pure switches without an effect on the signal, so that an excellent large signal behavior is achieved.