Base Station Antenna Circuit Board
Minimum Line Width : 3MIL ;
Minimum Line Spacing : 3MIL ;
Drilling Diameter : ≥ 0.1mm ;
Processing Size : 600 * 1200mm
Plate Thickness : 0.1-10mm ;
Processing Layers : 2-20 layers;
Special Process : Thick gold plate, ultra thick plate, depth control drilling, back drilling, hole filling electroplating, copper slurry plug hole, mechanical blind hole, etc.
Surface Treatment Processes : Include OSP, gold precipitation, silver precipitation, tin precipitation, gold plating, pure gold plating, thick gold plating, nickel palladium gold plating, nickel plating, tin plating, tin spraying, etc.
A. Thickness Selection
Thickness is mainly based on the microstrip antenna operating bandwidth, feed network design and antenna efficiency three factors to choose.
- a, PCB thickness affects the impedance bandwidth of the microstrip antenna. The smaller the PCB thickness, the larger the array size, the smaller the operating bandwidth of the microstrip antenna.
- b, the thickness of the medium affects the conductor loss of the microstrip line, which in turn affects the efficiency of the microwave RF antenna. Based on the above factors, the author's design experience is to choose 10mil or 20mil thickness for small arrays, 20mil thickness for large arrays, and 10mil thickness for microwave RF boards.
- c, the thickness of the PCB determines the line width of the microstrip line in the impedance change section of the feed network. For RO4350B board, the thickness of 20 mils, 50Ω and 100. Ω microstrip line line width were 1.13mm and 0.27mm, corresponding to the microstrip antenna resonance length at 24GHz is about 3mm. if the impedance of the microstrip conversion section of the feed network is too small or too large, will cause the microstrip antenna line is too wide or too narrow, the microstrip antenna line is too broad, prone to cause structural interference. If the line of microstrip antenna is too narrow, it will cause processing difficulties.
B. The Type of Antenna
Microstrip array antennas are categorized into parallel-fed arrays and series-fed arrays according to the feeding method. Parallel-fed arrays feed longer lines, resulting in greater losses in the feeder network. For large-scale arrays, antenna efficiency is often limited, so the simpler wiring of series-fed arrays is generally preferred. Series-fed arrays are resonant antennas with a smaller operating bandwidth than parallel-fed arrays, but series-fed structures are easier to achieve weighted excitation.
C. The Interconnection of Antenna and RF Chip
At present, domestic and foreign chip manufacturers have mass-produced 24 GHz RF chips in the market. In the zero IF radar architecture, the pins of the RF chip are directly connected to the microstrip transceiver antenna port. When using antenna circuit board (HF board) + multilayer FR4 + microwave RF board (HF board), the interconnection between the antenna and the RF chip is realized through metallized perforations.