Kana iyo yakakwira frequency / microwave radio frequency chiratidzo inopihwa mukati PCB dunhu, kurasikirwa kunokonzerwa nedunhu pacharo uye dunhu zvinhu zvichange zvisingadzivisiki kuburitsa huwandu hwekupisa. Iyo yakakura kurasikirwa, iyo yakakwirira simba rinopfuura nepakati pePCB zvinhu, uye kuwedzera kupisa kunogadzirwa. Kana tembiricha yekushanda yedunhu ichidarika kukosha kwakayerwa, dunhu rinogona kukonzera mamwe matambudziko. Semuenzaniso, iyo yakajairika inoshanda parameter MOT, iyo inozivikanwa kwazvo muPCBs, ndiyo yakanyanya tembiricha yekushandisa. Kana tembiricha yekushanda ichipfuura MOT, kuita uye kuvimbika kwePCB wedunhu kuchatyisidzirwa. Kuburikidza nemusanganiswa we electromagnetic modelling uye kuyedzwa kuyerwa, kunzwisisa hunhu hwekupisa kweRF microwave PCBs kunogona kubatsira kudzivirira kuderedzwa kwekuita kwedunhu uye kuparara kwekuvimbika kunokonzerwa nekupisa kwakanyanya.

Kunzwisisa kuti kurasikirwa kwekuisa kunoitika sei mumidziyo yedunhu kunobatsira kutsanangura zviri nani zvinhu zvakakosha zvine chekuita nekupisa kwekuita kwepamusoro-frequency PCB maseketi. Ichi chinyorwa chichatora microstrip transmission line circuit semuenzaniso wekukurukura nezvekutengeserana kune chokuita nekushanda kwekushisa kwedunhu. Muchikamu chemicrostrip chine mbiri-mativi PCB chimiro, kurasikirwa kunosanganisira kurasikirwa kwedielectric, conductor kurasikirwa, kurasikirwa nemwaranzi, uye kurasikirwa kwekudonha. Musiyano pakati pezvikamu zvekurasikirwa zvakasiyana wakakura. Nezvimwe zvishoma, kurasikirwa kwekudonha kwepamusoro-frequency PCB maseketi kunowanzo kuderera. Muchikamu chino, sezvo kukosha kwekurasikirwa kwekudonha kwakadzikira kwazvo, kucharegeredzwa kwenguva iripo.

Kurasikirwa nemwaranzi

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.

Iwo maparamendi emidziyo yedunhu ane chekuita nekurasikirwa nemwaranzi anonyanya dielectric anogara uye PCB zvinhu ukobvu. Iyo yakakura yedunhu substrate, iyo yakakura mukana wekukonzera kurasikirwa nemwaranzi; iyo yakaderera iyo εr yePCB zvinhu, iyo yakakura kurasikirwa nemwaranzi yedunhu. Kunyatsoyera huremu hwezvinhu, kushandiswa kwematete edunhu substrates kunogona kushandiswa senzira yekumisa kurasikirwa nemwaranzi kunokonzerwa neakaderera εr wedunhu zvinhu. Iko kurudziro yedunhu substrate ukobvu uye εr pakurasikirwa kwemwaranzi yedunhu imhaka yekuti ibasa rinoenderana nefrequency. Kana ukobvu hwedunhu substrate husingapfuure 20mil uye frequency yekushanda yakaderera pane 20GHz, kurasikirwa nemwaranzi kwedunhu kwakadzikira. Sezvo mazhinji edunhu rekuenzanisa uye kuyerwa mafambiro muchinyorwa ichi akadzikira kupfuura 20GHz, nhaurirano iri muchinyorwa ichi haichafuratira kukanganiswa kwekurasikirwa nemwaranzi pakudziya kwedunhu.

Mushure mekuregeredza kurasikirwa nemwaranzi pazasi 20GHz, kurasikirwa kwekuiswa kweiyo microstrip yekufambisa mutsara wedunhu kunosanganisira zvikamu zviviri: dielectric kurasikirwa uye conductor kurasikirwa. Chiyero chezviviri zvakanyanya zvinoenderana nehupamhi hwedunhu substrate. Kune matete substrates, conductor kurasikirwa ndicho chinhu chikuru. Nezvikonzero zvakawanda, zvinowanzoomera kunyatsofanotaura kurasikirwa kwekondakita. Semuyenzaniso, kushata kwepamusoro kwe conductor kune pesvedzero huru pane kutapurirana maitiro emagetsi emagetsi. Iko kushata kwepamusoro kwefoiri yemhangura haingoshandure iyo electromagnetic wave propagation yenguva dzose yeiyo microstrip wedunhu, asi zvakare inowedzera kurasikirwa kwemutyairi wedunhu. Nekuda kwekuita kweganda, pesvedzero yemhangura foil roughness pane conductor kurasikirwa zvakare inotsamira frequency. Mufananidzo 1 unofananidza kurasikirwa kwekuiswa kwe50 ohm microstrip transmission line maseketi zvichienderana neakasiyana PCB ukobvu, ayo ari 6.6 mils uye 10 mils, zvichiteerana.

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.

Kuti ugadzirise dambudziko rekupisa redunhu, iyo yakanakira yakaonda dunhu inofanirwa kuve neanotevera maitiro: yakaderera kurasikirwa chinhu chedunhu zvinhu, yakatsetseka mhangura yakaonda nzvimbo, yakaderera εr uye yakakwirira yekupisa conductivity. Kuenzaniswa nedunhu repamusoro εr, iyo conductor hupamhi hweiyo impedance yakafanana inowanikwa pasi pemamiriro epasi εr inogona kuva yakakura, iyo inobatsira kuderedza conductor kurasikirwa kwedunhu. Kubva pakuona kwekupisa kupisa kwedunhu, kunyangwe mazhinji epamusoro-frequency PCB wedunhu substrates ane urombo hwekupisa conductivity hukama nemakondakita, iyo yekupisa conductivity yedunhu zvinhu ichiri yakakosha parameter.

Nhaurirano dzakawanda pamusoro pekupisa kwekupisa kwematunhu substrates kwakatsanangurwa muzvinyorwa zvekare, uye chinyorwa ichi chichataura mamwe mhedzisiro uye ruzivo kubva muzvinyorwa zvekare. Semuenzaniso, equation inotevera uye Figure 3 inobatsira kunzwisisa zvinhu zvine chekuita nekupisa kwekuita kwePCB yedunhu zvinhu. Muequation, k ndiyo thermal conductivity (W/m/K), A ndiyo nzvimbo, TH tembiricha yenzvimbo inopisa, TC ndiyo tembiricha yenzvimbo inotonhora, uye L ndiyo chinhambwe pakati pekupisa uye kwaitonhora.