UHF Fractal Antennas: Solutions for Radio Links Using Matlab Simulations

2020 ◽  
Vol 26 (3) ◽  
pp. 179-184
Author(s):  
David Vatamanu ◽  
Simona Miclăuş

AbstractThe paper proposes the use of MATLAB simulations as a first step in identifying proper antennas to be used in specific ultra-high frequency (UHF) communication links. Giving that fractal antennas provide interesting features, we aimed at comparing a few of their significant parameters with those of a monopole antenna so as to ensure signal coverage between two real sites situated at 5.82 km distance in a mixture of urban and flat – open terrain conditions. We started from the requirements imposed to the return loss of the antenna and to the link margin, we established their desired thresholds and then computed solutions regarding which antenna type in the set provide the highest received power and on which frequency sub-bands can be successfully used. The studied fractal antenna set were from the series Koch, Koch loop and Sierpinski. The chosen radio link refers to a real situation on the map. Generally, different narrow bands were provided by each antenna regardless of its type, but still, comparing them with the monopole, better solutions could be identified.

2018 ◽  
Vol 7 (2.8) ◽  
pp. 529 ◽  
Author(s):  
Ch Ramakrishna ◽  
G A.E.Satish Kumar ◽  
P Chandra Sekhar Reddy

This paper presents a band notched WLAN self complementaryultra wide band antenna for wireless applications. The proposed antenna encounters a return loss (RL) less than -10dB for entire ultra wideband frequency range except band notched frequency. This paper proposes a hexagon shape patch, edge feeding, self complementary technique and defective ground structure. The antenna has an overall dimensionof 28.3mm × 40mm × 2mm, builton  substrate FR4 with a relative dielectric permittivity 4.4. And framework is simulated finite element method with help of high frequency structured simulator HFSSv17.2.the proposed antenna achieves a impedance bandwidth of 8.6GHz,  band rejected WLAN frequency range 5.6-6.5 GHz with  vswr is less than 2.


A comb shaped microstrip antenna is designed by loading rectangular slots on the patch of the antenna. The antenna resonating at three different frequencies f1 = 5.35 GHz, f2 = 6.19 GHz and f3= 8.15 GHz. The designed antenna is simulated on High Frequency Structure Simulator software [HFSS] and the antenna is fabricated using substrate glass epoxy with dielectric constant 4.4 having dimension of 8x4x0.16 cms. The antenna shows good return loss, bandwidth and VSWR. Experimental results are observed using Vector Analyzer MS2037C/2.


2018 ◽  
Vol 7 (2.6) ◽  
pp. 217
Author(s):  
B Sekharbabu ◽  
K Narsimha Reddy ◽  
S Sreenu

In this paper a -3 dB, 90-degreephase shift RF quadrature patch hybrid coupler is designed to operate at 2.4GHz. Hybrid coupler is a four-port device, that’s accustomed split a signaling with a resultant 90degrees’ section shift between output signals whereas maintaining high isolation between the output ports. The RF quadrature patch hybrid coupler is used in various radio frequency applications including mixers, power combiners, dividers, modulators and amplifiers. The desired hybrid coupler is designed using FR-4 substrate with 1.6mm height in High Frequency Structure Simulation (HFSS) and the same is fabricated and tested. The designed Hybrid coupler is examined in terms of parameters like insertion Loss, coupling factor and return Loss. The simulation and measurement results are compared. Major advantages of the RF quadrature patch hybrid couplers are that they are compatible with integrated circuit technology.


2013 ◽  
Vol 684 ◽  
pp. 303-306
Author(s):  
Eugene Rhee ◽  
Ji Hoon Lee

There are various feeding methods of antenna like as coaxial probe, coupling, parasitic elements, and impedance matching. This paper adopted the microstrip line method as the feeding method of the antenna. The high frequency structure simulator is used to analyze the characteristics of the T-shaped microstrip antenna with various patch dimensions. In comparison with the basic microstrip antenna, this proposed T-shaped microstrip antenna with 40.38 % of patch dimensions has the optimum characteristics of resonant frequency, return loss, and radiation pattern at 2.0 GHz band.


2020 ◽  
Vol 10 (24) ◽  
pp. 8843
Author(s):  
Oh Heon Kwon ◽  
Keum Cheol Hwang

In this paper, a Spidron fractal dipole antenna with a ferrite-loaded artificial magnetic conductor (AMC) is presented. By applying ferrite composed of nickel–zinc with a high permeability value, a compact AMC that operates in the broadband frequency range within the high-frequency/very-high-frequency/ultra-high-frequency (HF/VHF/UHF) bands was designed. A Spidron fractal-shaped dipole antenna with a quasi-self-complementary structure was designed and combined with a miniaturized ferrite-loaded AMC. This allowed the designed AMC-integrated dipole antenna to operate in a wide frequency band, covering the HF/VHF/UHF bands, with low-profile characteristics. A prototype of the proposed Spidron fractal dipole antenna with the AMC was manufactured and measured and found to meet low VSWR (voltage standing wave radios) specifications of <3.5 within the 20–500 MHz bandwidth range. The simulated and measured results are in good agreement. The size of the Spidron fractal dipole antenna with the AMC is 0.03×0.026×0.001λ3 relative to the wavelength of the lowest operating frequency. The received power of the Spidron fractal dipole antenna with the AMC was also measured when it was applied to relatively small applications, such as a manpack in this case.


2018 ◽  
Vol 7 (4.5) ◽  
pp. 324
Author(s):  
Ghulam Ahmad Raza ◽  
Garima Saini ◽  
Naveen Kumar

This paper presents a novel patch antenna for TV white spaces applications. The shape of the proposed antenna is based on the shape of a wineglass. The dimension of the proposed antenna is 170 mm x 120 mm x 1.6 mm. After simulation, the proposed antenna resonates at 703 MHz with a return loss of -21.97 dB and covering a bandwidth from 495 MHz to 1540 MHz. Overall bandwidth coverage is 1045 MHz. So the proposed antenna is a wide band antenna covering almost the entire TV Ultra High Frequency (UHF) range. Simulated VSWR obtained at 703 MHz is 1.38 dB and simulated gain is 2.32 dB. The proposed antenna is fabricated using FR4 substrate and tested on Vector Network Analyzer (VNA). The measured return loss of fabricated antenna is -20.20 dB at 596 MHz. Proposed antenna shows the simulated radiation efficiency of 95%. Simulated and measured results showed good match between them. Proposed design is compared with few designs available in literature to validate its novelty and advantages. 


2017 ◽  
Vol 9 (10) ◽  
pp. 1931-1936 ◽  
Author(s):  
Kaijun Song ◽  
Yifang Zhou ◽  
Maoyu Fan ◽  
Yu Zhu ◽  
Yong Fan

A wide-stopband bandpass-filtering power divider with high-frequency selectivity has been proposed in this paper. The input and output feeding lines and eight 1/4 wavelength resonators are used to realize the signal transmission. In order to obtain good frequency selectivity, source-load coupling transmission path is used to generate transmission zeros near the passband. A four-way power divider with bandpass-filtering response and high-frequency selectivity is designed, fabricated, and measured. The measured results agree with the simulated ones closely in the desirable frequency range. The measured center frequency of the power divider is 2.38 GHz with input return loss of 31.2 dB, while the measured insertion loss is about 1 dB (not including ideal 6 dB four-way power dividing insertion loss). Moreover, the measured 3-dB bandwidth is 12% and the measured stopband attenuation is >15 dB from 2.59 to 7.7 GHz. In addition, two transmission zeros of 1.9 and 2.8 GHz are located near the passband. The measured output isolations are all >15.7 dB.


Author(s):  
Adolfo Morales-Diaz ◽  
Celso Gutierrez-Martinez ◽  
Jose Alfredo Torres-Fortiz ◽  
Jacobo Meza Perez ◽  
Brenda Escobar Mendez ◽  
...  

1970 ◽  
Vol 13 (2) ◽  
pp. 254-270 ◽  
Author(s):  
Cecil K. Myers ◽  
J. Donald Harris

Seven equipment systems were assembled to examine human auditory acuity from 8 to 20 kHz. Two loudspeakers and two earphones were examined, together with two types of stimulus (pure tones and narrow bands of noise) and two psychometric methods (Limits and Adjustments). All systems were capable of providing usably reliable thresholds on 28 ears throughout the whole frequency range. When carefully calibrated, several systems (those involving loudspeakers, as well as those involving earphones) yielded comparable reference threshold sound-pressure levels at the eardrum. A preference was expressed for a system using Bekesy threshold tracking with a changing-frequency noise band of 300 Hz, and for a discrete-tone system using the Method of Constants.


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