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Questions tagged [antenna]

Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g. TV or radio) waves. -Wikipedia

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Will this receiver work?

I'm just a beginner, trying to understand an antennas and transistors as an amplifier, I'm studying, please correct me. Here we have a voltage source, PNP bipolar transistor emitter-base-collector ...
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0answers
30 views

How can I measure RSSI of an antenna with an Arduino? [on hold]

How can I measure RSSI (Received signal strength) of an antenna with an Arduino? Is it sensible to use ESP8266 with Arduino for this?
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0answers
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CST Studio Space State Matrices

I am new to using CST Studio and I am trying to figure out how to see the state space matrices (A,B,C,D) of a designed antenna to describe its radiation pattern in other software. Any help on the ...
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2answers
47 views

Why voltage source has been connected via inductor at the output of LNA?

I have been reviewing the schematics of LoRaWAN Gateway designed by Microchip (Page 48). The output of the LNA has been connected to voltage source via inductor. ...
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0answers
27 views

Inductor for a GPS active antenna

I have been testing the GPS / GPRS development module A9G, Aithinker which uses an active GPS antenna, according to the schematic reference diagram, the value of the inductance is 82nH: The question ...
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7answers
5k views

Why is 50 Ω often chosen as the input impedance of antennas, whereas the free space impedance is 377 Ω?

In order to efficiently deliver power to a different part of a circuit without reflection, the impedances of all circuit elements need to be matched. Free space can be regarded as a further element, ...
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4answers
100 views

Does the EM radiation from AC power lines propagate through air or is it fixed around the line?

Because of the AC current flow, there is a changing magnetic field around the conductor, that in turn induces a changing electric field and vice versa But does the EM radiation get "loose" from the ...
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2answers
145 views

Can I use more than one antenna with a radio module (say rfm69) and switch between those antennas electronically, say by a transistor

I need to know the approximate direction of the radio signal coming to my module, and I have to use very simple hardware and software for this. (Just a microcontroller and one module) What came up ...
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0answers
14 views

Tips for designing a dual band patch antenna for 2.4 GHz and 5.0 GHz operation

I'm trying to design a dual band patch antenna hoping to hit 2.4 GHz and 5.0 GHz, the substrate material I'm using is FR-4 with a 4.1 constant. I tried some designs for a single patch and a 2x1 patch ...
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1answer
30 views

Removing the imaginary part of input impedance of a Monopole in HFSS

I am building a Monopole in HFSS for my project. Its structure is shown here : The input impedance at the desired frequency is : Now i need to eliminate the imaginary part , so that the voltage and ...
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0answers
9 views

Best way to divide TV roof antenna to several rooms [migrated]

I am renovating a new house (in the UK). The roof antenna at present is only connected directly to the main tv socket, I would like to add more tv points to most rooms in the house but am unsure of ...
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2answers
48 views

Analysis of an LC circuit antenna

I want to analyse a parallel LC circuit in terms of inputs and outputs as I am studying them in the context of using them as a tuned antenna. However I am unsure of where to identify the inputs and ...
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1answer
29 views

How to calculated weighted gain of antenna?

I have this test specification for testing antennas and it defines weighted gain as follows: The weighted gain is calculated from the transfer function (S21) using only the gain values within the ...
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0answers
30 views

Determining the Impedance of the antenna on a known circuit

I am stuck on how to approach the following problem: I have a graph with both the response of a short-circuit and an unknown impedance antenna. The only information I have from this graph is the ...
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1answer
45 views

Analog beamforming vs digital beamforming

I am reading some research articles on wireless communication where they talk about beamforming techniques and their differences in Multiple antenna Tx-Rx systems (MIMO). It says analog beamforming ...
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1answer
57 views

How the azimuth of the time base is synchronized with the azimuth of the rotating antenna?

How the early radars could know the angle of a basic radar rotating antenna? How the direction of the time base on radar screen is synchronized with the direction of the radar rotating antenna?
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0answers
10 views

rfm69 chip antenna

I'm just getting into RF and am trying to make a board with an RFM69 and a chip antenna (Link). In their datasheet it shows matching the impedance on the line that connects the antenna to the device, ...
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0answers
10 views

What will be Directional antenna gain formula, encompassing all lobes?

In the attached figure, one can find the antenna gain formula. But the authors have simplified it for the main lobe only. Can someone please let me know the exact form of the following simplified ...
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0answers
19 views

About Directional Antenna, Transmit Gain, and Rician fading

In my research, I assumed a directional antenna for the indoor environment. I took the approach of considering Rician fading channel b/w Transmitter \$T_x\$ and Receiver \$R_x\$. My received power is ...
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1answer
72 views

What type of current is used by a transmitter? [closed]

(Short question , No need to downvote): What is the required current type in a RF transmitter (AC or DC). Since Phones have a battery (hence DC) how do they power their transmitter if AC is required?
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1answer
53 views

Shortening a long antenna with a capacitance

In many circumstances it is not possible to make a dipole antenna that has the optimum length of \$\lambda/2\$ (or monopole with ground plane of length \$\lambda/4\$). Car antennas are for example ...
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1answer
22 views

Choosing between ipex connector and SMA Connector for LoRa, LTE and GPS

I have completed designing of PCB with LoRa (868 MHz), GPS and LTE (1800 MHz). Earlier version of my PCB had this SMA connector. But now the PCB will be placed in enclosure and I am thinking to ...
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1answer
90 views

What is needed link budget? [closed]

Assuming I want to send a signal 1 km away from a 2.4 GHz antenna with 5 DBI gain and recieving antenna of 2.15 DBI gain. What is the minimum needed power at the receiver (not the minimum transmitter ...
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5answers
273 views

Why are cell towers so high? [closed]

Why do cell towers need so much height? Does the height increase antenna gain because it may provide directionality?
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1answer
173 views

Why microwave links on cell towers have high frequency?

Why microwave links are in the higher microwave spectrum (I don't know exactly but I guess it's around 20-40GHz). If by Friis Equation higher frequencies have lower range then why use higher frequency ...
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0answers
84 views

How can I reshape this PCB antenna so that I can still use it with the given circuit?

I'm borrowing the RF design from the MICRF114 Development Kit. Here's user guide- http://ww1.microchip.com/downloads/en/DeviceDoc/50002433A.pdf The circuit I'm using is on p. 35 and the antenna ...
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1answer
143 views

How can a phone transmit the signal back to tower? [closed]

If cellphones have such a low power transmitter (around 200mW for LTE) and also doesn't have directionality then how can they talk back to the tower even though they are so powerful and built ...
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1answer
37 views

PCB antenna and SMA connector

I have a question regarding an integrated PCB Antenna that I would like to try out, however, if it fails I want to be able to use another SMA antenna. The PCB Antenna is an inverted F-antenna meaning ...
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2answers
54 views

How to derive voltage applied to an antenna, where transmitter power is known & identical tx/rx antennas are used with known gain/impedance?

Question: Imagine a transmitter + transmitter antenna with the following characteristics: 433Mhz transmitter transmitting 10dBm Into an impedance matched (50 ohms) antenna, omni-directional, 3dBi ...
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1answer
40 views

Horn antenna for radar sensor

I have InnoSenT SMR-314 and SMR-334 radar sensors that have quite wide horizontal radiation pattern of over 100 degrees (see datasheet on page 3). I would like to make the sensors far more directional ...
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2answers
40 views

Can UHF rfid pass thorugh few layers of clothes in a smart shopping system?

I am working on a smart shopping system and would like to know if a UHF rfid signal can pass through few layers of clothes in a bag as multiple clothes would be present in a bag and system has to ...
4
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0answers
63 views

Flat Yagi Antenna Enclosure

So, i was annoyed that my Yagi Antenna was enclosed in a plastic-tube, which let it roll around and fall off the table occasionally, but without its enclosure the elements hooked in anywhere. So i ...
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1answer
47 views

For a transmitting Antenna, can the gain be positive in decibel scale?

Gain in dB scale of the transmitting antenna is: $$G=10\cdot\log \frac{P_o}{P_i}$$ The input power will always be larger than the output power. However, I see a lot of radiation pattern graphs with ...
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0answers
39 views

Active phased antenna array for Wi-Fi efficiency compared to a directional antenna?

I'm interested in mesh networking of poorly controllable autonomous aerial vehicles (like blimps), so i wonder whether it is viable to use a phased antenna array versus a few traditional directional ...
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1answer
34 views

Lightning protection for Antenna Connector

I want to add lightning and ESD protection for the antenna used with my PCB (Wireless Gateway). The antennas that will be used with my PCB are Pole Mount Antenna. There are three different types of ...
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3answers
93 views

Two TVs use the same antenna, but one affects the other

I’m having a problem with my TVs. I will call them TV1 and TV2. TV1 is Asanzo brand, and TV2 is LG 4K, which is much more expensive. After replacing the antenna wall socket of TV2 (The TV is near to ...
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2answers
45 views

Help Shielding RF Anechoic Chamber - FM Stations

a collegue and I acquired a surplus small anechoic chamber (8 ft x 8 ft) for making some pre compliance test measurements, and we're running into the issue of FM Stations being only attenuated around ...
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1answer
105 views

Yagi Calculator vs. Bruteforced values?

I started trying to build my own Yagi. So i ran into maybe some very well known Websites that show how to do it - however, i wanted to try with some theory first, before actually attempting to build ...
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1answer
57 views

Mounting orientation recommendations for PCB spring antenna?

I have been looking at 868MHz through-hole spring antennas for an application, but I can't seem to find any sort of information in datasheets regarding layout recommendations. Here's the most ...
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0answers
21 views

Radiation Resistance of Dipole Antenna [duplicate]

Length of a Dipole antenna is 17 cm connected to HF(3-30MHz). How can we measure Radiation Resistance of this antenna
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1answer
70 views

Impedence Matching of Antenna and Coaxial Cable

There is a scenario based question which is confusing for me Antenna had four rods each 15cm arranged as a plus sign. its brass shielding was cut and it had two 75 ohm coaxial cables in it. one 10 cm ...
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1answer
26 views

How do the Ripple Limit lines get determined on antenna measurements?

I'm doing an S21 ripple measurement through a VNA and I understand how the measurement is done, but I don't understand how the limit is determined. I know you can specify the limit in dB and then you ...
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1answer
119 views

UHF transmitter Range for 50 W

Very curious to know the range of 50 W transmitter of UHF range in nautical miles? The antenna used is 1/4 wave antenna of Jaybeam company. Can someone tell the exact formulation to find out the ...
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2answers
66 views

RF range at 169 Mhz

I'm planning a sensor network for agriculture (that apparently doesn't exist yet in this form) and I'd like to understand the possibilities of the radio link. A good number of in-the-field soil ...
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1answer
64 views

Do not understand why current flows in undamped oscillator circuit, and getting troubles in practice

I want to make my own antenna, so I started to make a generator. I found scheme below (only without a K key in the bottom) in internet, and it seems to be exactly what I was looking for. There PNP ...
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1answer
52 views

RF Output Power vs Antenna gain

I have a RF device which work on 2.4 GHz and Output power is 30 dBm (1 W), RF output is connected to a whip antenna (gain 2 dBi, omidirection), distance track between RF pad to antenna is kept as ...
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1answer
55 views

Understanding the Practical Application of a Simple Antenna made from Coax

I am here today to gain a deeper understanding of the fundamentals of using antennas in RC applications. I am trying to understand what exactly is going on with a particular 2.4GHz receiver a picture ...
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1answer
50 views

Impedance Matching Network with tracks+connectors in between (practice)

I've been struggling on how to design (and develop in practice) an impedance matching network with some traces/tracks/paths (whatever you wanna call it) and some connectors in between. So here is the ...
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1answer
63 views

dBmi Meaning in Testing

I'm having trouble making sense out of this requirement, in terms of how to test for it. I have a specification stating that for an RF power level measured in dBmi (let's call that power level S ...
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1answer
33 views

True near field distance for a short monopole antenna

Antenna properties: Height x Diameter = 3.3 inches x 1.4 inches Test Frequency: 900 MHz (Wavelength = 33 cm or 13 inches) I see some conflicting formulas to calculate the near field distance for ...