Carry a case, using is test of heart science and technology measures a solution, those who finish the radiation stray of product of wireless intelligence terminal is final optimize.

 

Case of some wireless intelligence terminal wants a place:

 

 

● GSM850 RSE checks harmonic radiate 3 times to exceed bid

 

Volume of abundant of ● 2.2GHz frequency is minor

 

 

Graph stray of the 1 radiate before debugging checks a result

 

 

Graph 2 radiation is conducted to check a result before debugging

 

Debug equipment:

 

● Keysight CXA N9000A+ N9311X is covered

 

Above all, whether to travel through conducting in the light of origin of stray radiation of 3 harmonic analysis, through checking test and verify the abundant that noise conducts below this frequency is measured in 9dB above. Next move of train of thought arrived on radiant noise.

 

Be aimed at radiation problem, we should search the noise that gives interference, use spectrum analyzer analyses what can faster essence allows to find out plan in frequency domain. We use sexual price to compare analyzer of tall CXA N9000A spectrum here, tie-in use N9311X covers a medium magnetic field annular bougie will scan the near field noise of the mobile phone. Can send the harmonic with aerial area larger now presence through using the annular probe of inferior sensitivity, if the graph shows 2.55GHz peak value 3 times,achieved – 43.29dBm.

 

From the point of test result, harmonic exceeds bid very serious, the noise signal of this and aerial area is very similar, considering conduct suspicion to had eliminated, what focussed aerial section because of the key of this analysis is nonlinear parts of an apparatus. From if the graph shows a principle 4 times,the graph can see, the harmonious switch of aerial is regular job, as a result of parts of an apparatus of linear of dispute of aerial switch itself, because this acknowledges the influence of aerial switch above all. aerial switch bypass (aerial is normal still) like the graph 5 are shown, discover right now the noise of 2.55GHz can be reduced – 55.7dBm left and right sides, because this can decide the noise of aerial area,harmonious switch is caused.

 

As a result of,be here only 3 harmonic occurrence problems of GSM850, and limits of can faster affirmatory the strongest radiation, the magnetic field that because this need not go further,uses tall sensitivity is annular probe is farther exact location.

 

Graph result of radiate of near field of the 3 2.55GHz before debugging

 

 

Graph bypass of 4 harmonious switch

 

 

Graph result of radiate of near field of the 5 2.55GHz after debugging

 

The abundant that is in radiation stray in the light of 2.2GHz frequency dot next measures inadequacy, can cover a medium low sensitivity magnetic field with N9311X first annular bougie and come the near field noise that scanning and dot measure a mobile phone, the below half share that if the graph shows the signal that discovers this frequency and 750MHz 6 times,area of radiate of the strongest near field amasses in PCB among them network of a power source, network of this power source can pass the LED with the chip of more high frequency composition and more noise and key-press area.

 

Through consulting power source and chip documentation are informed its switch frequency it is 1.9M about, the power source noise of this frequency composition can move in modulation process intermediate frequency signal frequency two side. Because use the probe intelligence of inferior sensitivity to decide place board,fluctuating however is cause of probable radiation stray signal partly partly, cannot decide an exact position however. Right now we need to be used further set in the magnetic field with taller precision is annular probe is perpendicular perhaps will define the strongest area to magnetic field probe. Final discovery is in in 750MHz+/-17MHz red circle indicative area is the strongest. The test consults the graph is shown 7 times please as a result, the near field radiate near here 750MHz is – 83.21dBm, 2.25GHz is in radiate of the biggest near field to be – 44.18dBm.

 

 

 

Graph the 6 750MHz before debugging and radiate of 2.25GHz near field are the strongest area

 

 

 

Graph the 7 750MHz before debugging and result of test of radiate of 2.25GHz near field

 

Because 2.25GH is 3 harmonic of 750MHz about, accordingly we do filter wave to design in the light of 750MHz above all. Should try to base band signal to overcome this kind of interference filter wave, prevent high frequency composition travels and move move. Like the graph 8 are shown is one kind recommends circuit, among them capacitance C1, C2 and L2 can be chosen as equipment, add this circuitry in the graph the power source of designation of 6 yellow block diagram makes filter wave near incident port.

 

 

Graph 8 proposals add filter wave circuitry

 

The has Max Hold of near field scanning again result after adopting plan of this filter wave can consult the graph shows result of near field radiate 9 times, the near field radiate near here 750MHz had dropped – 92.42dBm, 2.25GHz was in radiate of the biggest near field to drop – 53.08dBm:

 

 

 

Graph the 9 750MHz after debugging and result of test of radiate of 2.25GHz near field

 

Our reentrance darkroom finishs the radiate inside limits of whole frequency band to stray scans and conduct scanning finally, final result asks reference to pursue 10 with the graph 11 are shown. Can see radiation stray result has clear improvement, conduct radiation to also be improved somewhat at the same time.

 

 

Graph stray of the 10 radiate after debugging checks a result

 

 

Graph 11 radiation is conducted to check a result after debugging

 

 

This case announced to us the method that the radiation stray that through using spectrum appearance and near field probe check a solution one kind to complete installation of wireless intelligence news report debugs. The equipment that a fast essence permits to reach tall sex price to compare often can finish test and verify of research and development efficiently.