Pe a fafaga le faailo o le alaleo maualuga/microwave i le PCB matagaluega, o le gau e mafua mai i le matagaluega lava ia ma mea o le matagaluega o le a mautinoa lava e maua ai se aofaiga faapitoa o le vevela. O le tele o le gau, o le maualuga o le mana e ui atu i le mea PCB, ma sili atu le vevela na gaosia. Pe a sili atu le vevela faʻaogaina o le matagaluega i le tau faʻatatau, o le matagaluega e ono mafua ai ni faʻafitauli. Mo se faʻataʻitaʻiga, o le MOT faʻaogaina masani, lea e lauiloa i PCB, o le maualuga o le vevela faʻaogaina. Pe a sili atu le vevela o le gaioiga i le MOT, o le faʻatinoga ma le faʻamaoni o le PCB o le a lamatia. E ala i le tuʻufaʻatasia o faʻataʻitaʻiga electromagnetic ma fua faʻataʻitaʻiga, malamalama i uiga vevela o RF microwave PCBs e mafai ona fesoasoani e aloese mai le faʻaleagaina o le gaioiga ma le faʻamaoni faʻaleagaina e mafua mai i le maualuga o le vevela.

O le malamalama pe faʻafefea ona faʻaogaina le gau i mea faʻasalalau e fesoasoani e faʻamatala atili ai mea taua e fesoʻotaʻi ma le faʻaogaina o le vevela o taʻavale PCB maualuga. O lenei tusiga o le a avea le microstrip transmission line circuit e fai ma faʻataʻitaʻiga e talanoaina ai fefaʻatauaʻiga e fesoʻotaʻi ma le faʻaogaina o le vevela o le matagaluega. I totonu o se microstrip circuit ma se fausaga PCB lua itu, gau e aofia ai dielectric gau, conductor gau, radiation gau, ma leakage gau. O le eseesega i le va o vaega gau eseese e tele. Faatasi ai ma ni nai tuusaunoaga, o le leiloa leakage o tulaga maualuga PCB circuits e masani lava matua maualalo. I totonu o lenei tusiga, talu ai e maualalo le tau o le gau, o le a le amanaiaina mo le taimi nei.

Fa’aliga gau

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.

O fa’asologa o mea fa’ata’amilo e feso’ota’i ma le leiloa fa’avevela e masani lava ona fa’asolo ma le mafiafia o mea PCB. O le mafiafia o le vaega o le matagaluega, o le tele foi lea o le avanoa e mafua ai le leiloa o le radiation; o le maualalo o le εr o mea PCB, o le sili atu lea o le leiloa faʻavevela o le matagaluega. O le fuaina atoa o uiga o meafaitino, o le fa’aogaina o mea e mafai ona fa’aaogaina e fai ma auala e fa’afefe ai le leiloa o le radiation e mafua mai i mea tau eletise maualalo. Ole a’afiaga ole mafiafia ole su’ega ta’avale ma le εr ile gau ole fa’avevela fa’asolosolo ona o se galuega fa’alagolago i taimi. Afai e le sili atu i le 20mil le mafiafia o le mea faʻapipiʻi ma o le faʻaogaina o taimi e maualalo ifo nai lo le 20GHz, o le gau o le eletise e matua maualalo lava. Talu ai o le tele o faʻataʻitaʻiga faʻataʻitaʻiga ma fua faʻatatau i lenei tusiga e maualalo ifo nai lo le 20GHz, o le talanoaga i lenei tusiga o le a le amanaʻiaina le aʻafiaga o le paʻu o le radiation i luga ole faʻavevela afi.

A mae’a ona le amana’ia le leiloa o le radiation i lalo ole 20GHz, o le fa’aofiina o le gau o se microstrip transmission line circuit e masani lava ona aofia ai vaega e lua: leiloa dielectric ma gau ta’avale. Ole vaega ole lua e fa’alagolago ile mafiafia ole mea fa’avili. Mo substrate manifinifi, gau conductor o le vaega autu. Mo le tele o mafuaʻaga, e masani lava e faigata ona vaʻai saʻo le gau o le taʻavale. Mo se faʻataʻitaʻiga, o le faʻafefe o luga o se taʻavale e iai sona aafiaga tele i uiga faʻasalalau o galu electromagnetic. Le roughness luga o apamemea foil o le a le gata e suia ai le galu electromagnetic faasalalau sologa tumau o le microstrip circuit, ae faateleina ai foi le gau conductor o le matagaluega. Ona o le a’afiaga o le pa’u, e fa’alagolago fo’i le fa’atuputeleina o le pa’u pepa apamemea i le gau o le ta’avale. Fa’atusa 1 fa’atusatusaina le fa’aofiina gau o 50 ohm microstrip fa’asalalau laina laina fa’avae i luga ole mafiafia PCB eseese, lea e 6.6 mils ma 10 mils, faasologa.

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.

Ina ia mafai ona foia le faafitauli o le vevela o le matagaluega, e tatau ona i ai i le taamilosaga manifinifi lelei uiga nei: maualalo le leiloa o mea o le matagaluega, lamolemole kopa manifinifi luga, maualalo εr ma maualuga conductivity vevela. Pe a faʻatusatusa i mea taʻavale o le maualuga εr, o le lautele o le taʻavale o le impedance tutusa e maua i lalo o le tulaga o le maualalo o le εr e mafai ona sili atu, lea e aoga e faʻaitiitia ai le gau o le taʻavale. Mai le vaaiga o le dissipation vevela matagaluega, e ui lava o le tele o tulaga maualuga PCB circuit substrates e matua leaga lava conductivity vevela e faatatau i conductors, o le conductivity vevela o mea matagaluega o se vaega taua tele.

O le tele o talanoaga e uiga i le faʻafefe o le vevela o substrates circuit ua faʻamalamalamaina i tala muamua, ma o lenei tusiga o le a sii mai nisi o faʻamatalaga ma faʻamatalaga mai tala muamua. Mo se faʻataʻitaʻiga, o le faʻatusatusaga o loʻo mulimuli mai ma le Ata 3 e fesoasoani e malamalama ai i mea taua e fesoʻotaʻi ma le faʻaogaina o le vevela o mea faʻasalalau PCB. I le faʻatusatusaga, o le k o le vevela (W / m / K), A o le eria, TH o le vevela o le puna vevela, TC o le vevela o le puna malulu, ma L o le mamao i le va o le puna vevela ma le puna malulu.