Cat5e Shielded | RF Amplifiers | Cellular Repeate | Wireless Products

Coax Cable is a type of wire that consists of a center wire surrounded by insulating materials and then a grounded shield of braided wire. Coax cable is a cable type used to carry radio signals, video signals, measurement signals and data signals. The shield minimizes electrical and radio frequency interference.

Coax cabling is the primary type of cabling used by the cable television industry and is also widely used for computer networks, such as Ethernet. It is more expensive than standard telephone wire; it is much less susceptible to interference and can carry much more data than a telephone wire.

A coax cable consists of two conductors that share a common axis. The inner conductor is typically a straight wire, either solid or stranded and the outer conductor is typically a shield that might be braided or a foil. Coax cables exist because we can't run open-wire line near metallic objects (such as ducting) or bury it. We trade signal loss for convenience and flexibility.

Coax cable consists of an insulated center conductor which is covered with a shield. The signal is carried between the cable shield and the center conductor. This arrangement give quite good shielding agains noise from outside cable, keeps the signal well inside the cable and keeps cable characteristics stable.

The cable is designed to carry a high-frequency or broadband signal, as a high-frequency transmission line. Sometimes DC power (called bias) is added to the signal to supply the equipment at the other end, as in direct broadcast satellite receivers. Because the electromagnetic field carrying the signal exists (ideally) only in the space between the inner and outer conductors, it cannot interfere with or suffer interference from external electromagnetic fields.

Coax cables may be rigid or flexible. Rigid types have a solid sheath, while flexible types have a braided sheath, both usually of thin copper wire. The inner insulator, also called the dielectric, has a significant effect on the cable's properties, such as its characteristic impedance and its attenuation. The dielectric may be solid or perforated with air spaces. Connections to the ends of coax cables are usually made with RF converter.

Shireen Inc. has rolled out an optical repeater module designed for WCDMA networks. The RF module is used to monitor and control optical output power, LD bias current, received optical power, input and output RF signal power of Master, received FSK signal power and RF Gain control through the MCU. It is also used for RoHS compliant products.

The optical module for the repeater includes a linear analog PD with high sensitivity and a high power DFB laser, a low noise, linear RF amplifiers, as well as built-in Bi-Di components and FSK monitor. 9.6 and 19.2kbit/s data rates are provided for selection. In the slave, a laser with a wavelength of 1.5µm is selected as transmitter and an analog PD as optical signal receiver.

About Shireen Inc.

Shireen, Inc. designs, develops and manufactures components and systems for the Broadband Wireless, SCADA, Military and Telecommunications industries. Our solutions include everything from “mission critical” components for military communication systems to increasing the power of WiFi installations.

The optical module for the repeater includes a linear analog PD with high sensitivity and a high power DFB laser, a low noise, linear RF amplifier, as well as built-in Bi-Di components and FSK monitor. 9.6 and 19.2kbit/s data rates are provided for selection. In the slave, a laser with a wavelength of 1.5µm is selected as transmitter and an analog PD as optical signal receiver.

The optical module for the repeater includes a linear analog PD with high sensitivity and a high power DFB laser, a low noise, linear RF amplifier, as well as built-in Bi-Di components and FSK monitor. 9.6 and 19.2kbit/s data rates are provided for selection. In the slave, a laser with a wavelength of 1.5µm is selected as transmitter and an analog PD as optical signal receiver.

Efficiency and make of a RF amplifier determines the class it belongs to. Class E amplifiers are considered to be the best as they deliver significantly higher quality signals as compared to other class amplifiers. Transistor in Class E amplifiers works as a switch with a similar on/off function. Load network mechanism molds the current voltage and waveforms in a manner so as to avoid high voltage and current occurrences to limit power spread especially when the transistor switches on and off.

When the same transistor at the same frequency and output power is run in Class E, B and C amplifiers, Class E amplifier will operate more efficiently with power loss of less than 2.3 as compared to Class B and C amplifiers. They can be designed to handle frequency operations as large as 225-400 MHz during a fixed tune or narrow band operation. Class B and E amplifiers have same level of harmonic output. One big advantage of Class E amplifier is that they are “designable”, you can say customizable to make it simpler to understand. If you define the frequency variations and component effects in advance when designing Class E amplifiers then they will perform as expected.

To increase the efficiency of RF amplifiers it is important to reduce the power dissipation and still get the preset power output. Consider a RF amplifier and the greatest power dissipation in the entire system happens in the power transistor. Though the transistor has to be designed so as to be able to resist high power voltage and current, its power dissipation can be reduced by ensuring that both high voltage and current do not occur at the same point of time. If this can be attained through changes in the design then the efficiency of RF amplifiers can be increased substantially.

When “On” and the current is really high the transistor switch will work as a low resistance closed switch and the voltage will become zero. When “Off” and the voltage is high the transistor switch will work as an open switch and the current will become zero.

Similarly there are many different alternatives to increase the efficiency of Class E RF amplifier.

Type of coax cables used affects their use and longevity. Inferior quality cables can cause greater damage when used commercially on a distribution system. Hence it is important to select the right quality cables to ensure that you do not face any problems in future because of their faulty make. However it becomes really difficult to judge the quality of the cable just based on their manufacturing details as most of the times quantifiable data regarding their performance is not available.

To make things easier you can always rely on different types of cables available to make it easier for you to select the right type of cable based on your requirements. Whenever you need to buy new cable just go through the specifications and you should be able to buy the right type of it. Alphabetically coax cables are of 4 different types A, B, C and D.

Type A: More commonly known as semi-airspaced dielectric coax cables have longitudinal space running through it and so the popular name.

Type B: Though they look similar to type A coax cables, what differentiates them from type A cables is the foam used in their making. They are superior to type A as they last longer and are more robust. Previously manufactured type B cables easily soaked in moisture which ultimately affected their performance, however recent time cables come with a promise of better quality and higher level moisture resistance.

Type C: Popularly sold as “satellite downlead” Type C coax cables consists of low density copper braid and the screen is wrapped in very thin (not visible to the naked eye) silver colored material. Distinct quality of these coax cables is that the dielectric slides easily inside the screen, hence one has to be cautious when installing them.

Type ‘D’: Also known as “low loss cables” to disparate them from other similar cables used in VHF. Though you can find them in white sheath, they basically have brown sheath.

Most of the wireless systems are built using voltage controlled oscillators to control the movement of the frequency from source to unit. As the name hints two oscillators are used in dual-conversion systems. While one fine tunes all the input channel frequencies other functions at a pre-determined single frequency. They can be used either as an IC, module or discrete component circuit however they are more frequently used as part of an IC or a discrete circuit due to the price constraints.

Discrete-feature of voltage controlled oscillators is that they offer greater freedom to enhance performance of system including phase noise, tuning range, current consumption, output power, cost etc. Usually voltage controlled oscillators cannot be adjusted on as required bases, hence the RF engineer is faced with the challenge to develop a VCO that can be assembled without making any adjustments, such a VCO is called trimless VCO.

Designing a trimless VCO is not easy as it needs combination of design fundamentals and up-to-date RF engineering skills to make sure that the design is properly centered and that the oscillator tunes to the desired frequency as and when variations occur in supply voltage, component values and temperature. Developing a practically feasible RF VCO would mean you need to consider all the different types of oscillator topologies available, but the best and the most profitable topology has been that of Colpitts common-collector topology.

If you want to develop a low cost, flexible and high performance voltage control oscillator then using inductor-capacitor (LC) tank circuit which also includes a low-cost varactor diode and surface mount inductor. Oscillation frequency changes with every change in the inductor or capacitor, parallel resonance circuit in the oscillator tank controls the oscillation frequency. Inductor and varactor can be used to implement parallel- or series-mode network type resonance.

RF power amplifiers fall into different classes based on their peculiar endurance, linearity and distortion levels. Class E is one of the finest types of RF power amplifiers used to achieve greater efficiency. What sets them apart is that the transistor in Class E amplifier acts as a switch with ON/OFF function. To avoid recurring high voltage and current fluctuations, load network controls the voltage and current waveforms in such a manner that power dissipation is lowest at all the times especially in between switching transitions.

Another feature which differentiates Class E RF power amplifiers from Class B and C is that they can function with reduced power losses by an approx factor of 2.3. If class B and C amplifiers have drain efficiency of 65% the same would be 85% in case of Class E amplifiers. Both fixed tuned operations and narrowband operations for frequencies as wide as 1.8:1 can be performed using Class-E amplifiers. They can be even designed to work as they are without needing any “fiddling” or “tweaking”.

Efficiency for a Class E RF power amplifier lies in the amount of output power it gives without wasting much power. Below are the 6 principles that help the amplifier achieve its maximum productivity:

• When “On” transistor in the amplifier acts as a low resistance closed switch ensuring that the voltage remains close to Zero even when the current flowing is high.
• When “Off” transistor in the amplifier acts as open switch and keeps the current at zero even when the voltage is high.
• Voltage of the transistor will not rise until the current returns to zero
• Voltage of the transistor will become zero even before the current starts to increase
• Transistor voltage remains zero before the switch is turned “ON”
• Voltage slope of the transistor also remains zero at the time of turn “ON”

When all these principles are adhered to the RF power amplifier does not face situations of immediate increase in voltage and current and so are able to function as expected for a longer duration of time.

For those who are less familiar with RF amplifiers, it is a device through which the input can be amplified for a much intensified output. Sound signals by themselves are really weak but can be made stronger using an amplifier. They come in many different types based on their design which indicates the circuitry within it and are represented through classes A, B, AB, C and D.

Class A: Very low distortion, highly inefficient is how you can define class a amplifiers. Distortion level in an amp depends on the transistor; transistors in class A are little bias, and they remain half ON even when the device is idle, lot of power is thus wasted. With this bias are they actually useful? Yes they are mainly used for circuits requiring less power as Class A RF amplifiers will then maintain low distortion. Some extremely discriminating listeners are often found using high end Class A amps.

Class B: Though these are more efficient than Class A amps they too suffer from crossover distortion which takes place when the level of signal is low. They are used in all those low cost designs where the sound quality required is not that high like pocket transistor radios or clock radio circuits (these devices now use IC amplifiers).

Class AB: As you might have guessed Class AB combines all the good things about Class A and Class B. It is the most common variety of RF amplifiers seen in home stereos. With these, low signal would mean worst distortion and usually lowest at the time when signal reaches clipping point. Class AB amplifiers are equipped with two slightly ON transistors to eliminate crossover distortion present in Class B amplifiers.

Class C: Tremendous distortion caused by Class C makes them unsuitable for using in audio circuits; so are used only in RF circuits. Even in RF circuits filters are used to ensure that the final signal received is acceptable. They are more efficient then all the above Classes.

Class D: Though Class D amplifiers have been around for more than 5 long decades they can be seen in recent time semiconductor devices only recently. Advance power capacity, speed and efficiency of latest semiconductors make it less expensive to use Class D amplifiers in them. While all the above mentioned Classes use semi conductor devices in linear mode Class D uses them in OFF and ON mode just like switches.

Performance of a high power RF amplifier depends on its resiliency to provide outstanding performance for a much longer period of time that is most likely to be more than 20 years. Resiliency of an amplifier is termed as ruggedness in the electronics world. Most of the amp manufacturers consider ruggedness as one of the most crucial aspects of their design process.

From times known silicon based technologies like bipolar or LDMOS have been used to manufacture high power RF amplifiers. Though they are cost effective, they have low ruggedness ratings. LDMOS has an integral damaging mechanism formed into the structure of the transistor which reduces the function of the amplifier at high operating voltage.

Checking Ruggedness:
At times power supplied to the amplifier can be really high, ruggedness refers to its ability to withhold the power mismatch condition and deliver expected results without any failure or long term degradation. High power amplifier is reliable only if it displays ability to handle huge power distribution internally in the active area without hindering its performance. Although no features or qualities can be used to determine ruggedness it is generally a function of magnitude and phase of the mismatch, the thermal dissipation properties of the amplifier and the output power level conditions.

Semi conductor device manufacturers gauge ruggedness in high power amplifiers differently. Some maintain that the amplifier is ok if the output remains the same under all circumstances. However this is not an appropriate measure because amplifiers manufactured using the Bipolar technology do deliver desired results though the test damages some of the cells. The result remains unaffected because other active cells provide the required power at a higher temperature, so the performance is not affected.

Few others specify that the amplifier can be considered as reliable so far as it does not show more than 20% shift in DC test parameters.

Cell phones keep you connected everywhere you go, however they have a limitation and that is they need appropriate signals to be able to connect you to others. When the signals are low or are not available then it is nothing less than an empty device of no use. You feel frustrated in situations like this, but now no more because now we have cellular repeater, a cell phone signal amplifier.

What is a cellular repeater? As commonly defined in the wireless telecommunications industry cellular repeater is a type of BDA (Bi-Directional Amplifier) used to improve cell phone reception with the means of a reception antenna, an internal rebroadcast antenna and a signal amplifier. They are a smaller version of the broadcast towers used by network providers to be implemented in a building. The best part of using them is that it is really easy to install, even you by yourself can do it.

Here is a step by step guide on installation of cellular repeater:

• Cellular repeaters are available in kits and can be bought from a nearby cellular store. Along with it you will also need some household tools and hardware supplies.
• You need to fit the repeater at a place where your cell phone shows maximum coverage. Hence ascertain the area in your building with maximum coverage by moving around with your cell phone, stop when it shows full network availability.
• Fix the “Donor” antenna bracket against the wall this can be done using few wooden screws and a screwdriver. Loosen the bracket at the top so as to fit in the donor base, tighten the collar once done.
• Now it is time to connect the coax cable to a power source, if you have one outside then this should not be a big problem. If not then you will have to look for the nearest power source to the donor inside the house; drill a hole into the wall, window or door; pass the cable through it and connect.
• Fix the BDA next to the power source, plug in the cord
• Fix the other end of the coax cable into the Donor and screw the coverage antenna on a central wall that is common for all the rooms in the house. Ensure that you fit the cable high on the wall so as to receive optimum benefit
• Fix the other end of the coax cable into the BDA output, run the cable up to the coverage antenna and fix it in the coax input given on the antenna.
• Do not leave the cable hanging down the walls fix it appropriately using “U” clamp staples and use silicone paste to seal all empty spaces around the holes.

Cables – they are everywhere we use them in one or other electrical appliances but what is special about Coax cables. An easy paradigm to understand them would be human body - just like arteries carry blood to different parts of our body cables are used to carry electricity needed to run different electric appliances. Coax cables are one among the many different types of cables available in the market. Though mainly used in computers they are also used in video and radio electronics. Its core objective is to transform electricity between the main power source and the disparate parts of the appliances.

How do you identify coax cables? Generally all cables consist of inner and outer layers, as you strip the outer layer in these cables you will notice that the inner layer consists of copper wire wrapped in white insulator which again has a copper screen layered over it. Number of copper wires in the inner layer can vary depending on its capacity; more wires would mean that the cable will be able to carry more electricity at a much faster speed.

White insulator is generally made of solid polyethylene mainly because it is less expensive and easily available. Copper screen consisting of braided copper wires is layered over the insulator for added flexibility. The outer layer consists of black plastic; it is an essential element of a cable as it traps the electricity inside the cable, so you do not get a shock when you touch the cable.

Though they have been traditionally used to carry electricity they are also made to carry radio signals as the inner copper wiring and the copper screen run on the same geometrical axis. It would be worth noting that it is because of this particular feature that these cables are called coaxial (having a common axis) cables. Outside magnetic forces can easily interrupt or terminate radio signals. However the coaxial nature of coax cables and the plastic cables which create a perfect vacuum inside do not allow the signals to escape and hence they are used for transmitting radio signals.

Voltage controlled oscillators are commonly abbreviated as VCO. The VCO's are electrical circuits that yield an oscillatory output voltage. A VCO is an oscillator whose output frequency is proportional to the applied input voltage. The parts of a VCO circuit has a LC tank circuit with an inductor(L) and a capacitor(C) along with one or two transistors accompanied by a buffer amplifier. A VCO gives a periodic output signal where the output signal parameter is directly related to level of input control voltage. The center frequency of a VCO is the frequency of the periodic output signal formed by the VCO when the input control voltage is set to a nominal level. The voltage-controlled oscillator has a characteristic gain, which often is expressed as a ratio of the VCO output frequency to the VCO input voltage.

VCO's often utilize a variable control voltage input to produce a frequency output. The control voltage input typically may be tuned so that the VCO produces a desired, operational frequency output. The input control voltage is then adjusted up or down to control the frequency of the periodic output signal. A voltage controlled oscillator is capable of changing an oscillating frequency in response to a change in control voltages. A VCO typically employs one or more variable capacitors commonly called as varactors to allow for adjustment of the frequency of oscillation for the VCO. The tuning range of the VCO refers to the range of oscillation frequencies attained by varying the varactors.

Two important parameters in VCO design are sweep range and linearity. Linearity correlates the change in frequency or the VCO output to the change in the control voltage. The sweep range is the range of possible frequencies produced by VCO control voltage. Various types of VCO's have been discovered so far. VCO's comprised of bipolar junction transistors have been used to generate output ranging from 5 to 10MHz.

Voltage controlled oscillators are basic building blocks of many electronic systems especially phase-locked loops(PLL) and may be found in computer disk drives, wireless electronic equipment such as cellular telephones, and other systems in which oscillation frequency is controlled by an applied tuning voltage. The voltage oscillator components are almost an inevitable part of all digital communication equipments. VCO's are used for producing local oscillator signals (LO) which are in turn received by the transmitter and the receiver systems for the frequency up conversion and the down conversion respectively. Wireless subscriber communication units such as the GSM use voltage oscillator circuits for generating radio frequency signals. The VCO's are also employed in many synthesizer and tuner circuits and one best example for that is Television. A high frequency VCO is used in applications like processor clock distribution and generation, system synchronization and frequency synthesis.

You are often suggested to buy RF amplifier when you are out there planning to buy a radio. Know why? Because amplifiers are simple devices which enhance the sound quality you receive from audio devices. RF (radio frequency) amplifiers are especially designed to go with radios. They receive varied input signals in the form of current, voltage or others and transform them into output signals with larger amplitude based on the input signal.

Though both the input and the output devices use different circuits, signals received and sent by them are generally of the same type. Uninterrupted signal is generated as the power supply created output circuit receives resistance in varying levels from the input circuit to stable the current. Based on the amount of signals received from the input circuit by the output circuit one or more pre-amplifiers may work together to enhance the signal to create powerful output and send it to the RF power amplifier (PA).

Different types of RF amplifiers are pulse, multi-carrier, low noise, buffer, bi-directional and limiting amplifiers. Various types of them make it little difficult to select the right type of RF amplifier, however the choice can be made easier if you focus on their disparate performance specifications like operating frequency, design gain, output power and gain flatness.

• Different RF amplifiers have different frequency range for which their specifications are guaranteed, this is called operating frequency
• Design gain refers to the ratio of output to the input and is usually denoted in decibel
• Conditions like load, temperature, supply voltage and VSWR (Voltage Standing Wave Ratio) affect output. Output power refers to how the output will be affected under any such condition
• Gain flatness refers to the gain variation depending on the operating wavelengths

Output VSWR, noise figure (NF), monolithic microwave integrated circuit (MMIC) technology and input VSWR are some secondary specifications you should check when you are thinking of buying RF amplifier.

Now-a-days, the demand for frequency converter or frequency charger has been increased in many industries. The reason for this it’s fairly obvious, industries around the world need energy-saving devices in a variety of industrial applications and the frequency converters are of great help to solve the problem considerably. In a couple of years, the markets of frequency converters are expected to increase by fourfold its present size.

Frequency converter is one type of electronic device which converts alternating current (AC) from one frequency to other frequency and also its can change the voltage. A frequency converter typically consists of a rectifier stage that is inverted to produce AC of the frequency of your choice. There are many frequency converters available in the market, but RF converter is the most demanding devices in this field.

RF Converter can converters any GHz radio frequency to MHz unit and amplifies power to 10 watt. Thus, allowing users to take advantage of lower band with better penetration. The added high output power (10 Watts) increases the coverage by many folds. It offers a high power solution in a small package and also uses for mobile applications.

So if you are looking for buy RF Converter, then I suggest you SHIREEN NIC. It is a leading company of USA, which provides designs, develops and manufactures components and systems for the Broadband Wireless, SCADA, Military and Telecommunications industries.