How is the antenna length calculated? https://www.whwireless.com/ Estimated 15minutes to finish reading Meaning of half wavelength and quarter wavelength Half wavelength and quarter wavelength are widely used in engineering for antenna system design. Chalf Wavelength Chalf wavelength refers to the half wavelength distance of electromagnetic wave in the propagation direction. Specifically, for a certain frequency electromagnetic wave, its wavelength is the distance between two peaks or valleys in the propagation direction. Half wavelength is often used in the design of antenna systems, such as tuners or the selection of antenna lengths. Quarter Wavelength Quarter wavelength is the quarter wavelength distance in the propagation direction of an electromagnetic wave. Similar to half wavelength, quarter wavelength is also used in the design of antenna systems. Specifically, setting the antenna length to a quarter wavelength in some antenna designs allows it to resonate at a specific frequency for better waveguide characteristics. In addition, quarter-wavelength is also used to design components such as reflectors, transmission lines, and impedance matchers. We all know that the length of an ideal antenna is half a wavelength. The quarter-wavelength antenna we usually talk about actually needs to consider the “ground” in order to constitute a complete antenna, which is what we often call “unbalanced antenna”; the antenna itself is only a part of the antenna. Wavelength λ = speed of light c/frequency f 5GHz wifi antenna length calculation Wavelength λ = (3* 100,000,000)/ 5GHz Wavelength λ = 0.06 meters Generally use 1/4 wavelength ordinary wire, that is, the length of the wire used is about 1.5 centimeters 2.4GHz witi antenna length calculation Wavelength λ= (3 * 100,000,000) / 2.4GHz Wavelength λ = 0.125 meters Generally use 1/4 wavelength common wire, i.e. use a wire length of about 3.125 cm Why do antennas need half wavelength? The antennas we commonly use are generally resonant antennas, that is to say, they are in the form of standing waves, and the half-wavelength is the smallest unit that can constitute a standing wave. The reason for this is shown below: Can be seen, for the normal transmission of the signal, in the half-wavelength metal structure, the signal into the negative half-cycle, just to the end of the conductor, need to be reflected back to the reverse propagation; “negative half-cycle + reverse propagation” and become a positive signal, just can be superimposed, thus forming a standing wave. In this way, the signal can be gradually enhanced in this conductor structure, and the maximum amount of energy can be radiated per cycle. Why does an antenna need resonance? Oscillating charges on the antenna can radiate less energy per cycle (with reference to the ratio of the size of the radiated field to the near field), and only more charge pairs can participate in the radi...

Antenna Direction Diagram - How to see the antenna direction diagram? https://www.whwireless.com/ Estimated 15minutes to finish reading Antenna direction map, also known as radiation direction map or far field direction map, is to describe the antenna radiation characteristics (such as field strength amplitude, phase, polarization) and the relationship between the space angle of the graph. It is an important tool to measure the performance of antenna. By observing the antenna direction diagram, we can understand the parameters and performance characteristics of the antenna. The following is how to understand and view the antenna direction diagram of some key points: First, the basic concept of antenna direction diagram - Definition: antenna direction map refers to a certain distance from the antenna (far-field conditions), the relative field strength of the radiated field (normalized modulus) with the direction of change of the graph. - Representation: Usually represented by the power direction graph or field strength direction graph, but also used to describe the phase or polarization direction graph. - Graph type: the complete direction map is a three-dimensional space graph, but in practice, usually only focus on the two main planes (such as horizontal and vertical plane) on the direction map, called plane direction map. Second, how to view the antenna direction graph 1. Identify the type of graph: o Three-dimensional directional diagram: with the antenna phase center as the center of the sphere, the radiation characteristics are measured point by point on a sphere with a sufficiently large radius to be plotted. Three-dimensional directional diagrams can fully demonstrate the radiation characteristics of the antenna, but are more complex to draw and view. o two-dimensional directional map: from the three-dimensional directional map to take a certain profile (such as horizontal or vertical plane) to get the graphics. Two-dimensional direction diagram is simple and clear, easy to quickly understand the radiation characteristics of the antenna. 2. 2. Observe the key parameters: o Main flap: the radiating flap that contains the desired direction of maximum radiation, also known as the main flap of the antenna or antenna beam. The width of the main flap is a physical quantity that measures the sharpness of the largest radiating region of the antenna. o Auxiliary flap: The flap outside the main flap is called the secondary flap or side flap. Vice valve level is the closest to the main valve and the level of the highest level of the first side of the level of the valve. o before and after the ratio: the maximum radiation direction (forward) level and its opposite direction (backward) level ratio. o Direction coefficient: a measure of the antenna in the maximum radiation direction of the concentration of the density of the radiated power flow. 3. Analyze the radiation characteristics: o Directionality: the ability of the antenna to radiate electromagn...

Regarding dB, dBm, and dBi https://www.whwireless.com/ Estimated 15minutes to finish reading DB (decibels) DB is a relative unit used to represent the ratio between two quantities. It is usually used to describe the ratio of power or voltage (or current). Definition: (dB=10 \ log_ {10} \ left (\ frac {P_2} {P_1} \ right)) or (dB=20 \ log_ {10} \ left (\ frac {V_2} {V_1} \ right)) Among them, (P_1) and (P_2) are two power values, and (V_1) and (V_2) are two voltage or current values. Note: dB is a relative unit that represents the ratio between two quantities, not an absolute value. 1. The decibel calculation formula for power ratio: When comparing two power values, the decibel calculation formula is: DB=10log10 (P1P2), where (P_1) is the reference power (usually a fixed value), and (P_2) is the power to be measured. If (P_1) is 1 watt, the above formula can be simplified as: dB=10log10 (P2), where (P_2) is the power value in watts.   2. The decibel calculation formula for voltage (or current) ratio: When comparing two voltage (or current) values, the decibel calculation formula is: dB=20log10(V1V2) perhaps dB=20log10(I1I2) Among them, (V_1) and (I_1) are reference voltages and currents (usually fixed values), while (V_2) and (I_2) are the voltages and currents to be measured. If (V_1) or (I_1) is 1 volt or 1 ampere, the above formula can be simplified as: dB=20log10(V2) perhaps dB=20log10(I2) Here (V_2) and (I_2) are voltage and current values in volts or amperes. Note: In these formulas, (\ log_ {10}) represents the logarithm based on 10. If (P_2/P_1) or (V_2/V_1) (or (I_2/I_1)) is greater than 1, then the decibel value is positive; If it is less than 1, the decibel value is negative. The larger the decibel value, the greater the multiple of (P_2) relative to (P_1) (or (V_2) relative to (V_1), or (I_2) relative to (I_1)). DBm (decibels milliwatts) DBm is an absolute unit used to represent power values, with a reference point of 1 milliwatt (0.001 watt). Definition: (dBm=10 \ log_ {10} \ left (\ frac {P} {1mW} \ right)) Where (P) is the power value to be measured. For example, if the power of a signal is 1 watt, then its power is (10 \ log_ {10} (1000)=30 dBm). DBm is commonly used to describe the power of wireless signals or the sensitivity of receivers. DBm calculation formula dBm=10log10(1mWP) Among them, (P) is the power value to be measured, in milliwatts (mW). (1mW) is the reference power value, which corresponds to the power of 0dBm. Related information 1. Unit conversion: 0dBm corresponds to 1 milliwatt (1mW). For every 3dBm increase, the power doubles; For every reduction of 3dBm, the power is halved. For example, 30dBm corresponds to 1 watt (1W), because (10 \ log_ {10} (1000)=30) (because 1W=1000mW). 2. Common conversion values: o     30dBm = 1W o     40dBm = 10W o     50dBm = 100W 3. Precautions: DBm represents the absolute value of power, not the power ratio. In the cal...

What is Radio Frequency. https://www.whwireless.com/ Estimated 5minutes to finish reading A variable current (alternating current) is generated from a radio frequency transmitter, transmitted to an antenna through a copper wire, and radiated in the form of an electromagnetic wave, which is radio frequency Radio frequency is abbreviated as RF, which is short for high-frequency electromagnetic waves, and can also be referred to as radio waves Relationship between Wifi and RF The frequency band of RF is 3Hz to 300GHz The Wifi/wireless signals we use belong to a type of radio frequency, which operates in the 2 .4G and 5GHz frequency bands. 2.4GHz Range of 2.4GHZ ~ 2.4835GHZ, each channel occupies 20M, the 2.4G is divided into 13 channels (the world divided into 14 channels, China is only 13 channels); the distance between the center frequency of each channel is 5MHz of which 1, 6, 11 channels are completely non-overlapping channels. Bluetooth, microwave ovens, cordless phones also work in the 2.4GHz, generally cause interference to the wireless signal. 5GHz There are two main ranges: 5.15GHz-5.35GHz and 5.725-5.85GHz. China's 5GHz is also divided into only 13 channels, and all of them do not overlap each other. RF and frequency band When we use the device will generally say that this device supports dual dual-band, single dual-band, dual tri-band, etc., what do these mean? Multi-channel refers to how many radio frequency cards Multi-frequency means how many frequency bands are supported, generally speaking, all the way to support only one frequency, but now we can adjust the algorithm to make a road to support multiple frequencies Dual dual-frequency: two RF cards, one 2.4GHz, one 5GHz Single dual-frequency: one RF card through the software to achieve 2.4GHz and 5GHz switching Dual tri-band: two RF cards, one 2.4GHz, one 5GHz: 5GHz can be realized through the software 5GHz switching between high frequency and low frequency www.whwireless.com