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147 Threads found on edaboard.com: Near Far
Hello. I'm a new on this forum. I would like to show my last project. This is a device 3 in 1: bikecomputer + flashlight + powerbank Features: 1. Supply from two Li-Ion Cells 18650 Robiton 3400 mAh each 2. Embedded battery charger 3. Two bulbs. One has 10deg lens for far distance light. Other has 30deg lens for near distance light. Each bulb
as far as the 90 degree ends of the slots in the Comsol example. I would guess the total length of the slot, including the two tabs at the end, is approximately half wavelength, so that it resonates. Then the two 90 degree tabs are coupling energy from the waveguide (near those top edges of the waveguide are maximum current flow points).
The quoted equation is only valid in far field, 2 m is clearly near field. That's at least one possible explanation for deviation. For a more exact caluculation of transmission in near field, refer to antenna theory text books, e.g. Balanis.
What is your wavelength? In my experience a good absorber functions equally well in far or near field.
As far as the pole lies near a zero it will cancel out the effect of that pole.. it is correct. So i think it will cancel out one pole which is nearer to the Zero.
Hi, after calculating the trace width for 50 Ohm impedance line, the width is 0.30 mm. 116585 There is no problem at traces but on QFN pins which have a limited spacing, could RF traces have a neck near to SMT pins without affecting too much to RF line impedance? So, RF traces fit in a prope
It depends on your specifications ! Is it white smoke or black smoke or invisible smoke ? Is this for alarm purposes or process control? is it far from camera? What is between and behind cam? IR is best source for detecting smoke optically, but does cam have IR blocking filter? Do you want to measure smoke near ground? or high up? Is this for i
I had simulated micro patch antenna for 2.4 ghz and I can find s11 but please explain procedures to find other results like far feild radiation, near feild,efficiency,gain,directivity and all parameters
I fear your latest posts are further confusing your intentions. In terms of RF engineering, an antenna is a device with non-zero coupling to far-field. Inductive couplers are designed to receive or generate a magnetic near-field. They are used in a kHz to multiple 10 MHz range to transmit data or power wirelessly. They can be described as AC mag
Dear forum, I would like to do a sanity check on a near-field to far-field transform problem that I am struggling with. I have some planar recorded near-field data and would like to transform these data to far-field data and subsequently depict the field in spherical coordinates as E(r, theta, phi) where r is the radius, (...)
Some reservations: The LCRC model represents the transducer near it's resonance frequency, but not far from fundamental resonance frequency or e.g. overtone resonances. The "R" parameter respresents the sum of internal losses and external energy transfer, so it's supposed to change with the load conditions like interfacing the transducer with di
Dear Sir, Can you explain me, what is near field and far field in electromagnetics.
there ARE ways to do a reasonable far field measurement in a near field chamber. There are plenty of published papers on the method.
Hallo, i am currently working on a macro for cst mws and i am in search of sample cst source data. For example i need a.fsm or .rsd file for source fields(near/far). i need these file to do a debug run of my macro. thanks in advance rahul
Hi, What happens if the sub-relfector is in the near of antenna's main feed in a dual-reflector antennas? As feeds are normally electrically large, their farfield distance is quite large! and What is the solution? Cheers, Hadi
When I measure near field using a near field probe from antenna, PCB, ICs etc. (simply H-probe). I can see some peaks through Spectrum Analyzer(SA) according to clock frequency (in case of digital ICs). By the way, if the measured field is reactive field it may not be harmful as a EMI source because the field will be bounded near the (...)
I've never heard of P.I.C. before but I can tell you all landline modems use echo cancellation training with test patterns to cancel near and far end echoes. WiFi on the other hand gets cancellation from any transmitter that echoes off walls with a cancellation effect called Rician Fading or Rice Fading. This can generate a null when an echo is e
im simulating a spiral receiving antenna in freq. range 2-18Ghz. the antenna is placed closed to several metal conductors, and i want to simulate the radiation pattern of antenna. i want to know which one of the closed materials(metals) should be considered in simulation. i mean if we want to neglect some conductors near the antenna , how much it
Have you got an architectural diagram of the algorithm of how it will look in an FPGA? if not - drawing this is a good place to start before you even go anywhere near VHDL.
The radiated power of a small magnetical "antenna" at 24 Hz into free space (= far field) will be effectively zero. I guess, you are rather interested in the magnetical near field. It's proportional to Ampere-turns multiply coil area.
As far as I see, both ends have the same (13 mm) diameter. The IR sensor is apparently placed under a removable cap near the LCD display (as shown with the 400 photo). The ability to measure the temperature of small devices is specified by the 1:1 spot:distance ratio. A minimal spot size isn't specified, but it will be surely several mm.
Dear all, I am planning to simulate, and in a single setup, an FSS-Antenna system. I need to study the effect of different field patterns of a source antenna on the performance of an FSS structure. The simulation scenario has the following givens: 1- An antenna, in both the radiative-near-field (Fresnel region) and far-field (Fraunhofer region),
The diode is biased near the break down point. Once the diode avalanches it conducts and will remain in a conducting state or have a long recovery time unless quenched. With the addition of RL there is a voltage drop when current flows which will drop the voltage far enough to terminate the conduction in some diodes. In other diodes, especially InG
There's no principle limitation to operate a buck converter with a duty cycle slightly abobe zero. In so far, I don't understand the meaning of the diagram. There's also no limitation for the switch transistor, except for achieving reasonable efficiency. Voltage feedback is presumed, however. Duty cycles near zero will occur in any standard buck
Most of the antenna we can measure its characteristic in chamber, near field system. I wonder why some company build this kind of system? and what types of antenna must be test by this system.
I was wondering if anyone had any experience in near-field to far-field back transformations. I have a simulated far-field pattern and I'd like to back project the fields onto the aperture of the array. I've gotten NF-FF transformations to work and also NF planar back to the aperture to work but I'm having trouble with back projecting (...)
you did notice he said at 1 ( ONE) metre ? any of your link budget programs and other commented parameters are not going to work over such a short distance Dave Thank you, I did not notice the one meter distance! At 1 GHz, 30 cm wavelength, even with simple dipoles, one operates in the "near zone". This results
hi. I have a basic question in FDTD.I know formula and concepts of Huygens surface and I know formulas of near field to far field transformation (NFTFF) and also I can write matlab codes for this purpose.but I have a simple question. for NFTFF calculations,where I should place Huygens surface?before PML or in edge of PML?because as distance from
Hi every body:-) i am trying to design a simple current sensing interconnect , composed of a driver with current Iwin , lossy transmission line with impedance Z0, near and far- end voltage vwin, vout and receiver with termination resistance Rt nad received current Irec, i have 3 simple equations Iwin=IDsat=(w/2l)*mu*cox* (Vgs -vth)^2 ---> eq (1)
A dipole array is boxed in a rectangular box similar to radiation boundary box in HFSS. It radiates at 915MHz. The wavelength at 915MHz is 32cm. The far field is > 16cm. Can the power radiated be measured, say at 10 cm (in the near field) right outside the rectangular box assuming rectangular box is 10cm wide and long? Would the power radiated m
Hi all, Thanks to this forum, I've been able to get started in HFSS and obtained some working simulations of a copper planar spiral inductor on polyimide. I am simulating it in order to extract its inductance, series resistance and parasitic capacitance, for a near-field coupling application at frequencies ~1MHz. I have built inductors almost
I don't see current waveforms considered in your calculation, in so far I don't expect that it's correct for conventional power supplies with filter capacitor. For reasonable filter capacitor values, a "form factor" Irms/Idc of 1.6 for full wave rectifiers and 2.0 for half wave rectifiers is assumed. PFC power supplies have near to unity power f
In HFSS, my understanding is that power radiated from antenna is calculated at radiation box? So, does the radiation box act as a receive antenna? In real world scenario, what is the method to measure power radiated from an antenna? Isn't it to have a receive antenna in the far field or even the near field? Thanks.
For low frequency RFID, the "antenna" tags are indeed inductors. They work with inductive near field coupling, which is different from normal far field antenna radiation.
How current, near and far fields are related, depends on your geometry, and of course wavelength. Maybe you can give some additional information.
Capacitor vs. Battery Capacitor: * store energy in an electric field. * charge stored in a capacitor is proportional to the potential difference between the two plates * is charged by applying a voltage across the terminals which causes positive and negative charges * inner resistance is near infinite. * far lower energy density (compared t
Hi, Yes I know, but since I use far radiation boundary for my antenna, there is no need any more to use a near field one, and this for the same reason I specified above. I mean that near fields can be plotted anywhere inside the far field radion boundary, so why do I need to use the "near-field sphere".
As far as I know, the RFID antennas work in the near-field region, so you must obtain a good understanding of the behavior of your antenna in the near-field.
I don't understand how the waveform with V near 100 V is related to a buck converter circuit with 20V input supply. Subharmonic oscillation, if occuring, is a matter of the switch mode controller, so you should primarly show the controller circuit for a discussion of the effect. As far as I'm aware of, the oscillation occurs in a controller
Hi, I would like to know, how is the correct distance between the antenna under test and the probe using the planar near-field technique. Someone could help me to understand more about this. thanks Marco
both near field and far filed will work
I only see the Antenna Parameters (like power radiated, power incident, power accepted, etc...) for far Field. It does not do it in near Field, why? Impractical? Thanks.
there is always a comparison between near and far field measurement system. How much does a spherical or cylindrical near field system cost. thanks
Hi, I'm working on a nearField to farfield (planar scanning) code in matlab. I have just tried to test this code on an easy structure (open-ended waveguide) but the radiation pattern is different from that obtained using literature equation. Does someone know a working script to implement the NF2FF planar transformation ?
2) yes 3) near field is relate to polarized, but it's different method from far field.
Hello everyone, I'm using FEKO 5.4 and would like to determine the distance where the near-field converges to the far-field within a certain tolerance. I'm having a bit of difficulty in figuring out how to implement this entirely in FEKO. From what I can tell, I can't even subtract the near-fields from the far-fields in (...)
Dear all! How can I measure the polarization of antenna near field pattern ? In matter of fact, the type of polar. is only interested for me (Circular, Elliptic, Linear). Thanks in advanced!
Can anyone explain the near and far keywords in C??
Hi guys, My question is for a far-band simualtion by hfss, hou should i set the soluaiton frequency? e.g, my filter's Center frequency is 5Ghz (BW 0.5Ghz), so for the in/near-band simulaiton, my soluaiton freqeuncy is set to 5Ghz. If I want to simulate a far-band response from 20~25Ghz, should I still keep the same soluaiton (...)
I'm trying to simulate the near-field of a circular patch antenna driven by 2 probe feeds that are 90 degrees out of phase. Also, the center of the patch antenna is grounded. The model simulates fine (at 915 MHz), and I'm able to obtain some near-field plots using a sphere via the radiation menu in the project tree. However, the (...)