Rehefa ampidirina ao anatin’ny onjam-peo ny onjam-peo avo lenta/microwave PCB circuit, ny fatiantoka nateraky ny circuit mihitsy sy ny fitaovana circuit dia tsy maintsy hiteraka hafanana. Ny lehibe kokoa ny fatiantoka, ny ambony ny hery mandalo amin’ny PCB fitaovana, ary ny lehibe kokoa ny hafanana vokarina. Rehefa mihoatra ny sanda nomena ny mari-pana miasa amin’ny faritra, dia mety hiteraka olana sasany ny faritra. Ohatra, ny mari-pamantarana miasa mahazatra MOT, izay fantatra amin’ny PCB, dia ny mari-pana miasa ambony indrindra. Rehefa mihoatra ny MOT ny mari-pana miasa, dia ho tandindomin-doza ny fampisehoana sy ny fahamendrehan’ny faritra PCB. Amin’ny alàlan’ny fampifangaroana ny maodely elektromagnetika sy ny fandrefesana andrana, ny fahatakarana ny toetra mafana amin’ny RF microwave PCBs dia afaka manampy amin’ny fisorohana ny fahasimban’ny fizaran-tany sy ny fahasimbana azo itokisana vokatry ny hafanana avo.

Ny fahatakarana ny fomba nitrangan’ny fatiantoka ao amin’ny fitaovana fitetezam-paritra dia manampy amin’ny famaritana tsara kokoa ireo lafin-javatra manan-danja mifandraika amin’ny fampisehoana mafana amin’ny faritra PCB avo lenta. Ity lahatsoratra ity dia haka ny tsipika fifindran’ny microstrip ho ohatra amin’ny fifanakalozan-kevitra momba ny varotra mifandraika amin’ny fampisehoana mafana amin’ny faritra. Ao amin’ny faritra microstrip misy rafitra PCB roa sosona, ny fatiantoka dia misy ny fahaverezan’ny dielectric, ny fahaverezan’ny conducteur, ny fahaverezan’ny taratra ary ny fahaverezan’ny leakage. Ny fahasamihafana misy eo amin’ireo singa fatiantoka samihafa dia lehibe. Miaraka amin’ny maningana vitsivitsy, ny leakage fahaverezan’ny avo-matetika PCB faritra dia ambany dia ambany. Ato amin’ity lahatsoratra ity, satria ambany dia ambany ny sandan’ny fatiantoka leakage, dia tsy hiraharaha izany amin’izao fotoana izao.

Fahaverezan’ny taratra

Radiation loss depends on many circuit parameters such as operating frequency, circuit substrate thickness, PCB dielectric constant (relative dielectric constant or εr) and design plan. As far as design schemes are concerned, radiation loss often stems from poor impedance transformation in the circuit or electromagnetic waves in the circuit. The difference in transmission. Circuit impedance transformation area usually includes signal feed-in area, step impedance point, stub and matching network. Reasonable circuit design can realize smooth impedance transformation, thereby reducing the radiation loss of the circuit. Of course, it should be realized that there is the possibility of impedance mismatch leading to radiation loss at any interface of the circuit. From the point of view of operating frequency, usually the higher the frequency, the greater the radiation loss of the circuit.

Ny mari-pamantarana amin’ny fitaovana circuit mifandraika amin’ny fahaverezan’ny taratra dia ny dielectric tsy tapaka sy ny hatevin’ny fitaovana PCB. Arakaraka ny hatevin’ny substrate fizaran-tany no lehibe kokoa ny mety hahatonga ny fatiantoka taratra; ny ambany ny εr ny fitaovana PCB, ny lehibe kokoa ny taratra very ny faritra. Mavesa-danja ny toetra ara-nofo, ny fampiasana substrate manify faritra dia azo ampiasaina ho toy ny fomba hanonerana ny taratra fatiantoka vokatry ny ambany εr circuit fitaovana. Ny fiantraikan’ny hatevin’ny substrate circuit sy ny εr amin’ny fatiantoka taratra amin’ny circuit dia satria asa miankina matetika izy io. Rehefa tsy mihoatra ny 20mil ny hatevin’ny substrate ary ambany noho ny 20GHz ny fatran’ny asa dia ambany dia ambany ny fahaverezan’ny taratra. Satria ambany noho ny 20GHz ny ankamaroan’ny maodely sy ny fandrefesana faritra ato amin’ity lahatsoratra ity, ny fifanakalozan-kevitra ato amin’ity lahatsoratra ity dia tsy hiraharaha ny fiantraikan’ny fatiantoka taratra amin’ny fanafanana faritra.

Taorian’ny tsy firaharahiana ny fahaverezan’ny taratra eo ambanin’ny 20GHz, ny fatiantoka amin’ny fidiran’ny tsipika fifindran’ny microstrip dia misy ampahany roa: ny fahaverezan’ny dielectric sy ny fahaverezan’ny conducteur. Ny ampahany amin’ny roa dia miankina indrindra amin’ny hatevin’ny substrate circuit. Ho an’ny substrate manify, ny fahaverezan’ny conducteur no singa fototra. Noho ny antony maro dia sarotra amin’ny ankapobeny ny maminavina ny fahaverezan’ny conducteur. Ohatra, ny hamafin’ny tondra-drano dia misy fiantraikany lehibe amin’ny fifindran’ny onja elektromagnetika. Ny hamafin’ny varahina foil dia tsy hanova ny tsy tapaka ny onjam-peo elektromagnetika amin’ny microstrip circuit, fa hampitombo ny fahaverezan’ny conductor amin’ny faritra. Noho ny fiantraikan’ny hoditra dia miankina amin’ny matetika ihany koa ny fiantraikan’ny faharatsian’ny foil varahina amin’ny fahaverezan’ny conducteur. Ny sary 1 dia mampitaha ny fatiantoka fampidirana ny 50 ohm microstrip fifindran’ny tsipika fizaran-tany mifototra amin’ny PCB hatevin’ny samy hafa, izay 6.6 mils sy 10 mils, tsirairay avy.

The simulation results are obtained using Rogers Corporation’s MWI-2010 microwave impedance calculation software. The MWI-2010 software quotes the analytical equations in the classic papers in the field of microstrip line modeling. The test data in Figure 1 is obtained by the differential length measurement method of a vector network analyzer. It can be seen from Fig. 1 that the simulation results of the total loss curve are basically consistent with the measured results. It can be seen from the figure that the conductor loss of the thinner circuit (the curve on the left corresponds to a thickness of 6.6 mil) is the main component of the total insertion loss. As the circuit thickness increases (the thickness corresponding to the curve on the right is 10mil), the dielectric loss and the conductor loss tend to approach, and the two together constitute the total insertion loss.

The circuit material parameters used in the simulation model and the actual circuit are: dielectric constant 3.66, loss factor 0.0037, and copper conductor surface roughness 2.8 um RMS. When the surface roughness of the copper foil under the same circuit material is reduced, the conductor loss of the 6.6 mil and 10 mil circuits in Figure 1 will be significantly reduced; however, the effect is not obvious for the 20 mil circuit. Figure 2 shows the test results of two circuit materials with different roughness, namely Rogers RO4350B™ standard circuit material with high roughness and Rogers RO4350B LoPro™ circuit material with low roughness.

For thinner substrates, the use of smooth copper foil can significantly reduce the insertion loss. For the 6.6mil substrate, the insertion loss is reduced by 0.3 dB due to the use of smooth copper foil at 20GHz; the 10mil substrate is reduced by 0.22 dB at 20GHz; and the 20mil substrate, the insertion loss is only reduced by 0.11 dB.

This means that when the circuit is fed with a certain amount of RF microwave power, the thinner the circuit will generate more heat. When comprehensively weighing the issue of circuit heating, on the one hand, a thinner circuit generates more heat than a thick circuit at high power levels, but on the other hand, a thinner circuit can obtain more effective heat flow through the heat sink. Keep the temperature relatively low.

Mba hamahana ny olana amin’ny fanafanana ny faritra, ny faritra manify tsara indrindra dia tokony hanana ireto toetra manaraka ireto: ambany fatiantoka ny fitaovana faritra, malama varahina manify ambonin’ny, ambany εr sy avo mafana conductivity. Raha ampitahaina amin’ny fitaovana fitetezam-paritra amin’ny εr avo, ny sakan’ny conducteur mitovy amin’ny impedance azo amin’ny toetry ny εr ambany dia mety ho lehibe kokoa, izay mahasoa amin’ny fampihenana ny fahaverezan’ny conductor amin’ny faritra. Avy amin’ny fomba fijery ny fiparitahan’ny hafanana, na dia ny ankamaroan’ny avo-matetika PCB faritra substrates manana tena mahantra conductivity mafana mifandray amin’ny conductors, ny mafana conductivity ny faritra fitaovana dia mbola tena zava-dehibe masontsivana.

Resadresaka maro momba ny conductivity mafana amin’ny substrate circuit no nohazavaina tao amin’ny lahatsoratra teo aloha, ary ity lahatsoratra ity dia hanonona valiny sy fampahalalana sasany avy amin’ny lahatsoratra teo aloha. Ohatra, ity equation manaraka ity sy ny Figure 3 dia manampy amin’ny fahatakarana ny anton-javatra mifandraika amin’ny fampisehoana mafana amin’ny fitaovana PCB circuit. Ao amin’ny equation, k ny conductivity mafana (W / m / K), A ny faritra, TH ny mari-pana ny hafanana loharano, TC ny hafanana loharano mangatsiaka, ary L ny elanelana misy eo amin’ny loharano mafana sy ny loharano mangatsiaka.