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Post by chaos on Jun 16, 2020 20:43:22 GMT 5.5
This is the official thread for the SWANtenna project.
This post will be updated constantly regarding new developments.
Objective: '...to design a novel broadband dual-polarization antenna element suitable for astronomical observations at low frequencies, which could form the basic element of the proposed large size SWAN arrays.'
Specifications:
1. Dual orthogonal linear polarization reception, using two separate sub-units with relative orientation of 90 degrees.
2. Efficient radiative coupling over the band from 50MHz to 500MHz, with a return loss of more than 8dB over at least 80-320 MHz. (i.e. S11 < -8dB) 3. Total projected spawn of the structure (width*breadth) to be within one square meter, and an extended conducting reflector below, defining the ground plane (for the array), is to be an integral part of the design. 4. Assume Aluminum as the conducting material for the EM simulations, and a suitable non-conducting material may be considered for the central cylindrical hub (such as for housing Low-Noise Amplifiers, etc, with approximately 10cm diameter), and other support/isolation purposes, with emphasis on low-cost and ease of manufacture. You're allowed to use any available simulation package for EM simulations. Objectives for the first week (16/06/20-23/06/20): 1. FULLY UNDERSTAND THE PROBLEM STATEMENTBefore tackling this problem, we're going to discuss it as much as possible. Most of us don't know the first thing about how antennae operate, and there's a lot of specifications in the problem statement. We're dividing into groups, to answer each one of the following questions: 1. What is orthogonal, linear reception? How do antennae detect polarized electromagnetic radiation? How do we detect it using relatively oriented units? 2. What is radiative coupling? What is return loss? What does S11 mean? 3. How do antennae look like for astronomical observations? How can we make them fit in less than a square meter of area?
Reply with what problems you'd like to tackle. Next week, we're going to have another meeting, and everyone's going to explain their answers in this thread. I want a fully detailed forum post explaining the answers to your selected questions.
Resources: 1. antenna-theory.com 2. drive.google.com/drive/folders/1kW90LWpNwm6vtjB_RUMexwQlmiwQ4vEi?usp=sharing (All our material is dumped here.) |
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Post by HuLaLaBoO on Jun 16, 2020 20:56:26 GMT 5.5
I will dig up on Second point.
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Post by carthicc on Jun 16, 2020 21:02:10 GMT 5.5
I'll take care of the first topic
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Post by ArchDukeBarbatos on Jun 16, 2020 21:09:13 GMT 5.5
I will handle the third.
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Post by ArchDukeBarbatos on Jun 17, 2020 10:03:56 GMT 5.5
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Post by carthicc on Jun 19, 2020 13:52:15 GMT 5.5
1. What is orthogonal, linear reception? Linear: Linear polarisation is the most common form of antenna polarisation. It is characterised by the fact that all of the radiation is in one plane - hence the term linear. Linear polarization occurs when electromagnetic waves broadcast on a single plane (either vertical or horizontal). Linear polarized antennas must have a known RFID tag orientation and the RFID tag must be fixed upon the same plane as the antenna in order to get a consistent read. Horizontal polarisation: This form of antenna polarisation has horizontal elements. It picks up and radiates horizontally polarised signals, i.e. electromagnetic waves with the electric field in the horizontal plane. Vertical polarisation: This form of antenna is typified by the vertical elements within the antenna. It could be a single vertical element. One of the reasons for using vertical polarisation is that antennas comprising of a single vertical element can radiate equally around it in the horizontal plane. Typically vertically polarised antennas have what is termed a low angle of radiation enabling a large proportion of their power to be radiated at an angle close to the earth’s surface. Vertically polarised antennas are also very convenient for use with automobiles. Slant polarisation: This is a form of radio antenna polarisation that is at an angle to the horizontal or vertical planes. In this way both vertical and horizontally polarised antennas are able to receive the signal. Orthogonal: Wherever there are two polarizations of radio signals (Horizontal and Vertical), the transmitted and received radio signal to and from the antenna are said to be “orthogonal”. This means that the modulation planes of the two radio signal waves are at 90 degrees angles to each other. 2. How do antennae detect polarized electromagnetic radiation? How do we detect it using relatively oriented units? www.youtube.com/watch?v=ZaXm6wau-jc |
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Post by ArchDukeBarbatos on Jun 25, 2020 15:58:43 GMT 5.5
Radiative coupling:
Coupling is basically derieved from Electromagnetic Compatibility. Coupling is the path between the source of EMI to the victim of the interference.
In our context, it should be interpreted as merely bandwidth or the coupling if the astronomical source to our antenna via radiation.
Return loss:
Amount of radiation reflected from the antenna and lost forever. Shown in decibel or %. Applicable to both Tx and Rx due to reciprocity.
S11:
The return loss parameter. S from port 1 to port 1. As in the fraction of the total power that appears at the terminals of the same antenna.
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Post by yashwardhan on Jul 19, 2020 0:59:04 GMT 5.5
Progress Report:
Designs:
1. Fractal Bow-tie:
A solid bow-tie with fractals cut out of the bows to create multiple current distributions which in turn will create a multiband antenna ( not staggering bandwidth ). Focussing on a triangular fractal Bow-tie with 3 or more ( if possible ) iterations.
2. Log Periodic Toothed Bow-tie:
An advancement of the simple solid bowtie by carving teeth onto opposite edges of the two bows with different lengths and thicknesses with the biggest tooth being a quarter of the largest wavelength needed. The lengths and widths of the teeth being in a constant ratio with one another to provide a staggering bandwidth allowing to create a WBA.
Problems with designs
1. The common requirement of the two designs for a ground ( patch )for the antenna creates difficulty in aligning the central cylindrical hub to be connected to the antenna.
2. Placement of the two linear polarization antennas in a way to not hinder with the performance of the antenna ( as a whole ) and to fit the cylindrical hub in between.
Software:
1. 4nec2 software for preliminary construction and understanding of a bow-tie ( wired ) to get hands on to the solid bow-tie ( modified ), the end goal.
Tasks:
1. Search for solutions over the design problems associated with the cylindrical hub and the dual polarization alignment or come up with a new antenna design to overcome these obstacles without any compromise over the performance parameter limits.
2. Create a simple ( wired ) bow-tie on 4nec2 and juggle with the parameters so as to get an understanding on the performance and response to the stimuli given to the antenna
3. Search for a software capable of designing a ( SOLID ) bow-tie with the decided modifications ( LP TEETH or FRACTALS ) with as less complications as possible, with WIPL, CST Studio Suit, HFSS, Zeland IE3D to be given immediate priority before moving on to others
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