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swarg_eu

DVB-T2 Front End

30 posts in this topic
On 10/26/2020 at 2:19 PM, swarg_eu said:

for this type of antenna, a simple power splitter is not a solution (no phase shift between ports)

the patches need to be driven with a 180 deg phase shift, otherwise, there will be no main lobe in the radiation pattern (in its place will be a zero)

Therefore it uses a transformer (wire loop) that transforms the single-ended (asymmetric) to differential (symmetric, 180 deg phase shift) port

the rest of the PCB traces (GND below) ensures a proper impedance match 

on this kind of FEED , phase and z adapters...(pretty sure there some ...at least 3db) Not counting dielectric losses...just the splitters....

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it depends on how you look on the splitter/combiner 

- splitter, 2 output  ports with a 3dB "loose" compared to the input 

- combiner the output has a 3dB "gain" compared to the 2 input ports (assuming the phase and amplitude match)

the question is actually what you do with the splitted/combined signal 

 

in the case of an antenna, the feeding network for the patches splits the power while TX and combines the power while RX

the TX antenna gain and the radiation pattern is a result of the superposition (amplitude and phase) of the patches radiation 

the RX antenna gain and pattern are the results of the combined patch (pattern) signals (amplitude and phase) 

 

in the case of a passive antenna, the feeding network is the same for TX & RX resulting in the same pattern for TX & RX and doubling the patch count increases the antenna gain by 3dB (combiner/slpitter)

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11 minutes ago, Admin said:

swarg_eu,You can design such a divider...???

screenshot_2160.jpg

that not a problem,

 

but depending on the frequency a 90 deg hybrid or a ratrace is a better solution  

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1400 MHz-2600 MHz, broadband circularly polarized microstrip antenna with two gap-coupled probe feeds;

 

Dimensions ..

2160.jpg

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