a view shots of a selfmade 2,4Ghz WLAN Helix Antenna
Video Rating: 3 / 5
This video shows how I checked my LDG 4:1 Balun for SWR using the MFJ-269. 73, N7JFP.
Video Rating: 5 / 5
A 2 foot AM / Medium Wave Loop antenna in use.
Video Rating: 4 / 5
PC boards: Materials and processing are now a hot technology
The close proximity means that the signal traces can be much narrower and still meet 50-ohm impedance specifications. With FR-4's dielectric constant of 4, a 50-ohm trace is twice as wide as the distance to the ground plane. …
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Key aspects of RFID Passive tag design. For more information: www.agilent.com For a free evaluation copy of ADS: www.agilent.com
Video Rating: 5 / 5
U.S. Patents Awarded to Inventors in New Hampshire (Dec. 2)
An impedance matching apparatus includes a mismatch detection circuit that produces a difference between source and load impedances, a match network controller that produces a control value based on the difference, and a reconfigurable varactor match …
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Connector adapters warm the engineer's heart
For example, I have an RP-SMA to RP-TNC adapter which came with my D-Link ANT24-0700 external 802.11 antenna (an accessory which "saved the day" for me, see here.). Turns out I didn't need the adapter, but someday it may solve an RF-connector mating …
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U.S. Patents Awarded to Inventors in Texas (Dec. 17)
… a phase shift, a capacitive coupling change, an impedance change, or any other change which notes the presence of a target relative to the transceiver. The control circuitry may be used to change the amount of power applied to the antenna and/or to …
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U.S. Patents Awarded to Inventors in New Hampshire (Nov. 25)
A control circuit is provided for controlling the synchronous rectifier as the input voltage approaches the output voltage, so as to adjust average impedance of the conduction path over a discharge period of the inductor." The patent application was …
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KEMET Offers HiQ-CBR Series Surface Mount Multilayer Ceramic Capacitors for …
Typical applications include critical timing, tuning, bypass, coupling, feedback, filtering, impedance matching, and DC blocking. Field applications include wireless and cellular base stations, wireless LAN, subscriber-based wireless services, …
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Murata – SAW filter / power amplifier / magnetic stabilizer module for mobiles
It controls the characteristics of load fluctuation caused by changes in impedance that can occur when the user's hand, metal object or other materials come close to the antenna. With the growing numbers of frequency bands supporting 3G networks, …
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LDG Electronics Z-817H Instructional Video Part 1 How to install and use a Z-817H tuner with the FT-817 radio.
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Filling the sand in the reactor. SWR=1,6 initially. It first diminues down to 1.1 then stabilizes a moment and grows up to 1.2 when all is filled. So the antenna impedance modified to be best tuned (1.1) during the sand filling. CB transeiver was on channel 40 (for the best SWR with my system, with channel 1 SWR=2 and is bad)
60″ (1.5m) WiFi Pigtail N-type Male to RP-TNC
- 5 feet of cable USA Made LMR-240
- Antenna cable – Connects Access Points, Routers and Radio transmitters to Antenna
- Impedance 50 Ohms Frequency Range DC ~ 11 GHz
- LMR240/LMR-240 is a Registered Trademark of Times Microwave USA
- Ultra low loss characteristics ensure the maximum performance of your external antenna installation
Ultra Low Loss Cable is designed to transmit the maximum signal to your antennas. LMR-240 cable by Times Microwave USA meets Military Specifications with silver foil and silver coated copper conductors for less signal loss in runs up to 200 feet.. In this high quality cable, the dimensions and spacing of the conductors are uniform. Any abrupt change in the spacing of the two conductors along the cable tends to reflect radio frequency power back toward the source, causing a condition called stand
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Check out these Antenna impedance images:
QuantumFX ANT-104 Remote Controlled Rotating Outdoor Antenna
- HD/DTV/UHF/VHF remote-controlled rotating outdoor antenna
- DTV/HD ready and compatible when connected to your DTV tuner
- Rotates 360 degrees
- Impedance: 75 Ohms
- Built-in 25-30 dB signal booster
Full Band DTV/VHF/UHF Receiver
360° Rotation
Includes Wireless Remote Control
Easy Bracket Installation
Includes 50 ft. Coaxial Cable
List Price: $ 15.95
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The effect of input configuration on antenna impedance
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KEMET Offers HiQ-CBR Series Surface Mount Multilayer Ceramic Capacitors for …
Typical applications include critical timing, tuning, bypass, coupling, feedback, filtering, impedance matching, and DC blocking. Field applications include wireless and cellular base stations, wireless LAN, subscriber-based wireless services, …
Read more on Sacramento Bee
Myryad MT 100 FM stereo tuner
This is followed by a discrete class-A push-pull output buffer amplifier, which provides low output impedance and high drive capability. The MT 100 has eight separate power supplies. The signal-strength meter combines the signal-strength output from …
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U.S. Patents Awarded to Inventors in Oregon (Nov. 11)
11 — Electro Scientific Industries, Portland, Ore., has been assigned a patent (8054085) developed by Brian Johansen, Hillsboro, Ore., and Brandon John McCurry, Portland, Ore., for a "programmable gain trans-impedance amplifier overload recovery …
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Using the phase plot feature of T100 Vector Impedance Analyzer to find out the resonance frequency of an antenna.
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Plotting the impedance (Z) of an antenna from 100MHz to 170MHz with T100 Vector Impedance Analyzer.
Preliminary study of a shunt substitution method of measurement of antenna impedances at frequencies from 20 to 400 MC, (Mineola)
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Find More Antenna Impedance Products
Small Antennas:Miniaturization Techniques & Applications
Next-generation small antenna design techniques This authoritative text provides the most up-to-date methods on the theory and design of small antennas, including an extensive survey of small antenna literature published over the past several years. Written by experts at the forefront of antenna research, Small Antennas: Miniaturization Techniques & Applications begins with a detailed presentation of small antenna theory–narrowband and wideband–and progresses to small antenna design met
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Antenna impedance in the ionosphere
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More detail information on Pocket Two Way Radio Walkie Talkie: www.dealextreme.com – 1.4″ LCD display – Frequency range: VHF136~174, UHF400~470 MHz – 99 Channels – 5/6.25/12.5/25KHz – Working voltage; 3.7V – Battery: 1500mAh – Frequency Stability: -30 ~ +60 degree Celsius – Antenna impedance: 50 ohm – RF Power Output: 2W – S/N ratio: 45dB/42dB – FM range: 87~108MHz
Testing of a newly-built 160 metre AM transceiver at Chelsea on Port Phillip Bay near Melbourne. The receiver featured in a previous video. The transmitter is similar to the one presented here: www.angelfire.com It is crystal controlled on 1843 kHz. A centre-tapped 15 volt 1A power transformer is used for modulation. Efficiency is quite high – total Tx power consumption is 1A for approx 7 watts out on peaks. The IRF510 final stage does however need to be presented with an acceptable antenna impedance otherwise distortion can appear on the output, as happened here (the switched inductor in series with the antenna has since been replaced). The transmitter’s circuit is described in ‘Lo Key’ September 2011 – published by the CW Operators QRP Club.
Video Rating: 5 / 5
Using Ferrites
Ferrites work by greatly reducing the current flow, at the interfering frequency, in the 'antenna' that is the root of the problem. The 'wire' is made to look like a high-impedance at the interfering frequency, thus severely reducing the current flow, …
Read more on Radio magazine (press release)
開創量測系統新價值 無線/接線式整合系統崛起
目前所使用的多款接線式量測系統，均部署極為精確的時基(Timebase)、鎖相迴路(PLL)電路，與阻抗匹配(Impedance-matched)的訊號路徑。若單以原則來看，接線式系統可符合同步化作業的嚴苛需求。然而，接線式網路與無線網路卻可分別透過IEEE 1588與GPS技術，讓使用者在標準與 …
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A few nice Antenna impedance images I found:
Receiving marine weather fax transmission
Image by Richard Corfield (M0RJC)
Micro- and millimetre-wave signal measurement tools and best practices – Part 2
Their materials, structures and geometries are specially designed for a specific operating frequency range, to yield consistent impedance and reduce signal loss. Avoid compromising the performance of an expensive test system with poor quality or …
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A Tech's Guide to Component Design Factors in AM RF Gear
In the absence of design limits, if parameters (ie, antenna impedance, etc.) are estimated or uncertain, higher design factors are often applied, as a matter of engineering judgment. On the other hand, lower safety factors may be justified by a …
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Cowon D3 Plenue Review
Volume levels on the D3 go loud enough to power pretty much every phone below 100 Ohm impedance properly. The D3 is a bit quieter than other Cowon players, but it is still efficient enough. However, if your D3 comes with a volume-limited EU firmware …
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The Si4010 transmitter, the latest member of Silicon Labs’ EZRadio® line of wireless products, is the industry’s first single-chip remote control IC, requiring only one external bypass capacitor, a printed circuit board (PCB), battery and an external casing with push buttons to form a complete remote control. The Si4010 includes a patented antenna tuning circuit that automatically fine-tunes the antenna for optimum transmit power on every button press. With standard remote control designs, variations in the RF transmitter, component and antenna manufacturing tolerances and the environment can lead to large antenna inefficiencies and wasted power.
An additional feedback loop is incorporated into the power amplifier (PA) to maintain constant output power by monitoring the voltage at the output of the PA and adjusting the PA’s current drive to compensate for changes in the antenna impedance. This feedback loop works to maintain constant output power in spite of temperature variations and the “hand effect,” which, as stated above, changes the antenna impedance when a person’s hand is covering the remote control. The net result of antenna tuning is to provide consistently reliable and optimal performance on every button press while reducing the cost and design complexity of the RF matching requirements. Remote controls designed with the Si4010’s automatic antenna tuning feature can reliably and consistently operate at the government transmit limit for maximum transmit range.
Battery life is an important consideration for any portable electronic device, especially a remote control. When we consider typical remote control usage, more than 99 percent of the time, a remote control is waiting for a user to activate a button press. During this time, the Si4010 consumes less than 10 nA at room temperature, making it an ideal choice for battery-powered applications. Additionally, wake-on-touch GPIOs further minimize current consumption of the remote control and extend battery life.
One of the most important considerations in any remote control design is minimizing total system design cost, which is influenced by many factors besides component costs, including labor, inventory, test, and manufacturing yield. By far, the dominant low-cost RF remote control solution on the market today uses an MCU and a surface acoustic wave (SAW)-based RF transmitter.
The wide acceptance of this design topology stems primarily from its low cost and simplicity. A SAW device is resonated with transistor Q1 in a Colpitts oscillator structure to form the carrier frequency, and transistor Q2 provides the output power amplification and isolation needed for stable operation. Data from the MCU is applied directly to the SAW resonator to form the OOK modulated signal, and GPIO6 from the MCU supplies the voltage (VCC) to the SAW-based transmitter. This entire solution uses 24 external components, including the MCU, one bypass capacitor, a quartz crystal used to clock the MCU, and a PCB with a trace antenna and capacitor. It has an RF component cost (excluding the PCB, MCU and bypass capacitor) of .77 USD in 100,000-unit volumes. The .77 RF BOM cost does not include the cost of the MCU, bypass capacitor or PCB. Traditionally, this has been the lowest component cost solution available for reliable RF transmission. From a system cost perspective, the large BOM count increases other costs, such as labor, inventory and tests, and reduces manufacturing yield.
Silicon Labs – Wireless RF and ISM Band Transceiver IC. By leveraging mixed-signal IC design in standard CMOS, we are able to eliminate many discretes and use fewer external components than competing solutions.
Antenna Impedance Matching
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Ceramic Wafer: ceramic powders and sintering processes directly affect the quality of performance. Now the market ceramic used is mainly in 25 × 25,18 × 18,15 × 15,12 × 12. Ceramic chip area is larger, the larger the dielectric constant, the higher the resonant frequency and the better is the receiving. Most of the ceramic wafer design is square, to ensure that the resonance in the XY direction is consistent, in order to achieve signal receiving well-distributed.
Silver Plate: the silver layer of ceramic antenna can affect the resonant frequency. Ideal frequency of GPS ceramic should fall 1575.42MHz on the nose, but the antenna frequency is vulnerable to affect by the surrounding environment, especially built in the machine, Therefore, have to adjust the silver-coated form, to make sure the frequency remained at 1575.42MHz .
The Feed Point: ceramic antenna collects resonance signal through the feed point and then sent to the backend. Since the antenna impedance matching reasons, feed is generally not in the center of the antenna, but doing minor adjustments in the XY direction. This impedance matching method is simple and has no extra cost. Move only in the uniaxial direction is called a single partial antenna, do move in two axes are referred to as double-side.
The amplifier circuit: to bear the shape and size of the PCB ceramic antenna. As GPS has the characteristics of ground bounce, when the background is 7cm × 7cm without a break earth, patch antenna performance can be to the limits. Although restriction by the appearance of the exterior structure and other factors, but try to maintain a considerable size and the same shape. Amplifier gain selection should be with the back-end LNA gain. Before the required signal input of Sirf’s GSC3F, total gain shall not exceed 29dB, otherwise saturated signal will result in self-excited.
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Quick demonstration showing how an oscilloscope, an RF signal generator and a simple box with 5 resistors (3 – 50R0 and 2 – 1K0) can be used to observe antenna resonant frequency in the 7 MHz range. Note: This is no substitute for an Agilent VNA, but then, it isn’t going to cost as much either if this GPTE (General Purpose Test Equipment eg scope, signal gen) are just sitting around idle … More info (schematic of resistors in ‘magic box’, calculation of impedance using values read off O-scope): web.archive.org .
Video Rating: 5 / 5