# Tag Info

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Metal is efficient in blocking electromagnetic waves when surrounding an entire volume forming what is called a Faraday cage. So if you place your cell phone in a cage like that I can assure you that it's not going to be able to communicate with the outside world. You can use an empty paint gallon as a cheap DIY Faraday cage, if you want to test it by ...

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Smartphone cases aren't metal. Cheap ones are made of plastic (ABS or polycarbonate). The very high end ones which have glass front and back and metal edging will often use the metal edging itself as the antenna. This caused problems on the iPhone 4 when used by left-handers. In that design, the metal bezel was split into carefully sized pieces that were ...

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Only certain configurations of metal block RF. A enclosing Faraday cage for instance. Other configurations of metal (or other conductors or magnetics) radiate EM when driven. A wire dipole antenna for instance, or the reflectors and directors in a Yagi Uda. They radiate EM when electrical charges (electrons, et.al.) accelerate along the wire. Slots or ...

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Curves in the left are two different presentations how the reflection factor seen by the feeding circuit depends on frequency. The yellow curve is the standing wave ratio which is calculated from the absolute value R of the reflection factor with formula SWR= (1+R)/(1-R). It's not measured directly, it's calculated. You should see that it's quite near 1 at 2,...

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The plots on the right are the antenna patterns at 3 different frequencies. The plot on the left looks like it's the measured S11 (input return loss), though the scale values don't make sense.

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The +B is for the battery positive. You will not need it for the headphone jack. Most boomboxes have a headphone jack built in.

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Why does 1/4 wavelength have to have a ground plane and 1/2 doesn't? Here's how I think of it, a 1/2 wavelength dipole is just two 1/4 wavelength antennas back to back, and either can be considered the whip or ground plane. Or, a 1/4 wavelength vertical is just 1/2 wavelength antenna with the ground plane as the other 1/4 wavelength element. In this case ...

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Therefore I will select an antenna to only support one or two of the bands. I can select the band in my modem through software using the command AT+CBAND. Sadly, you're not in charge of selecting the band – your network operator is. So, all your considerations are in vain: you'll have to use what they are willing to offer you.

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A vertical quarter wave whip with ground plane applies a common trick in practical electromagnetics. The ground plane generates the mirror image of the whip and that mirror image behaves like it was feeded by inverted signal. The result is like a vertical half wave dipole in free space. Theoretically the ground should be a large planar surface but even a ...

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A quarter wave monopole antenna doesn't have to have a ground plane... unless you want it to radiate EM energy with a certain efficiency and pattern. EM radiation requires accelerating electrical charges, which usually implies a voltage differential between two separated areas in space. A conductive ground plane is a particularly good region of voltage ...

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I can't understand why we need to use a ground plane at 1/4 wavelength and 1/2 wavelength not needed. A 1/2 $\lambda$ dipole has voltage and current waves like this: - Picture from Wikipedia. Now, if you focus your eye at dead centre of the picture you will see that the voltage is always zero volts. This is because a dipole is optimally driven with a ...

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You want a magnetic loop antenna. A wire loop around the doorframe with a tuning capacitor on the left and cellphone on the right. Borrow a grid dip meter from your local ham radio club and adjust the capacitor to resonate at 13.56 MHz. The cellphone must be slightly within the loop. This will boost your signal to a range of a few meters if set up correctly. ...

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Option 1 should be best. It has less GND impedance than Option 2 because it is closer to the antenna and it has better capacitive coupling to the other GND layers. I do not understand the cited text and I can not think of a single reason why you not should connect all the GNDs you have together as good and close as possible. An antenna is like a ...

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Once happened something similar to us, also at 900MHz. We had a ceramic antenna soldered in our PCB with a very small ground plane. As the performance was very poor we contacted the antenna manufacturer and they propose adding a copper tape directly to our ground plane, that improved a lot the efficiency. The copper tape was something like this: https://www....

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Remove any metal underneath the antenna. The cut-out you see on the datasheet's "Bottom Metal" should apply to ALL internal layers regardless of how many layers you have. A metal layer underneath will shield emission in that direction. Anything you do which is not in accordance to the datasheet will tune the chip antenna to another frequency, they are ...

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You can certainly have your RF trace on the top layer, and the reference ground plane on layer 2 (or internal_1 as you call it) of a 4 layer board. You would just need to ensure the transmission line width is sized appropriately for the height between the two layers and the substrate material. You don't have to do anything special on the other two layers. ...

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What is the impedance of 20 pF @ 2.4GHz (3 Ohms)? How short ( no pun intended ) can you make a jumper at 0.5nH/mm? To get 3 Ohms you need 200pH or 0.4mm for a discontinuity from 50 OHms. A 0402 component is what 1mm? Does that make sense now that the RF cap is better? But the lowest impedance might be a jumper in series with a cap resonating at 2.4GHz....

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I would like just to add a comment on previous answer: The TEM wave has its E and H field completely in phase. In the matched transmission line, also the voltage and current are in phase (no standing wave), hence the standing wave means that voltage and current (E and H field) are 90 degrees out of phase. Before becoming a TEM wave it is "born" in the ...

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If the antenna and the line are perfectly matched there are no standing waves in the line? Correct. Standing waves occur as a result of reflections; if a reflected wave meets an incident wave on a transmission line they can interact to cause constructive and destructive interferance at certain points along the length of the transmission line, this is ...

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Carriers crossing junctions exhibit SHOT NOISE, proportional to $\sqrt { 2 q I_B}$, where $I_B$ is the current (number of carriers per time unit) flowing though the junction.

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I am not familiar with the use of the term heteroscedastic , but we are aware of many sources of noise that increase such as thermal noise increases with temperature and Partial Discharge Noise increases with voltage getting closer to the breakdown voltage. We also know that Zener diode noise increases with current.

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Since any PCB FR-4 materiel will cause EM field inaccuracies from losses, and any bits of copper will case reflection/reradiation, any realworld model will be in error. For fun, read up on the maths behind the stealth fighter "metal facets" thinking. A Russian wrote the paper.

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"So how do you think they came up with the 20W for their simulation?" I don't think it matters. The relative power density profile (antenna pattern) doesn't care what the input power is. However the absolute power density profile does. If you double the input power the power density at any given point doubles also.

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I'm not certain how you would go about this test other than to actually take power readings around all the transmit lobes on the antenna itself. I can say this: efficiency is directly related to the material of which the antenna is made. Copper is far more efficient than aluminum.

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You need to match impedance between each block and between the antennas and blocks (every connection in the diagram). As long as you do that, the impedance of block1+block2+antenna will be equal to the nominal terminal impedance of block1 itself. In this case, you can design matching networks for each connection based on the nominal impedances. However, if ...

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1- Go to Menu/Place/Arc/Arc(Edge), 2- Place an Arc close(but not necessarily accurate) to the desired dimensions, 3- While the arc is selected, On Properties panel, adjust all sizes including thickness, start angle, End Angle, Radius ,... 4- Go to Menu/Tools/Preferences/PCB Editor/General, 5- Change the Rotation Step to correct value. For example if your ...

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You might use a diplexor in the antenna feed. I believe such a construct will provide 2 output channels.

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Yes, that's possible, and you'll find directive multi-band antennas commercially-off-the-shelf. These internally mostly resemble Yagi-Uda antennas, but don't have the same director sizing as actual Yagi-Udas. Probably, they were designed starting as Yagi-Uda, and then stochastically optimized in simulation until they worked well enough on multiple ...

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I am going to simplify this for you. No, you cannot use the 2.4 GHz antenna for 700 MHz. The parabolic part of the antenna may still provide a little bit of gain, but it won't work nearly as well as it did at 2.4 GHz. More importantly, the antenna is probably not passive. I base this on the fact that the band specified is very narrow if it were a purely ...

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The gain and directivity of a parabolic dish is inversely related to the wavelength of the signal and directly related to the size (diameter) of the dish. The wavelength at 700 MHz is approximately 3.5 times greater than 2.4 GHz. Hence keeping the dish size constant and lowering the frequency (increasing the wavelength) by 3.5 will result in a drop in gain ...

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Can I use a 2.4 GHz rated parabolic MIMO antenna for 700 MHz Verizon 4G LTE data? The gain of an antenna, that is, how much it focuses in one direction, is pretty much proportional to its size divided by the wavelength. Generally, antennas don't work (well) for frequencies they're not designed for, but you can consider a parabolic dish more of a reflector ...

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The “single” antenna does not have multiple bands as far as what the data sheet says; there are 4 antennas offered in the data sheet all operable in slightly different bands. Read carefully the data sheet and note the subtle difference between the four part numbers. This means that you need a different BoM for each band anyway.

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You would need to build up an evaluation model of your design, tune the L and C values, and put those in the production BOM. You could design the match circuit to hit both bands of the antenna but you aren't going to get as great performance of either.

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Obviously the geometry of each define the optimal gain and beamwidth. It's like asking I have 2 different reflectors with lenses for a bulb. Can I use them? The datasheets can tell you best how to use them. Helix antenna are very sensitive but when tuned give more gain and a narrow beamwidth for point-to-point long distance better performance.

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U.FL is the connector; the antenna is printed on the attached PCB. It depends on the design, but in general you'd use one or the other. To design it to use both would be a lot of trouble just to increase the cost. It's probably to give some flexibility in the way the module is integrated into the larger design.

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