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Nested Loop Antennas This Low-Cost Five Band Loop Array Blends Into the Background
Nested Loop Antennas This low-cost five band loop array blends into the background. G. Scott Davis, N3FJP This multi-band nested loop antenna array replaces my tribander Yagi, which is only up 20 feet. Inspired by suggestions from Bill Wisel, K3KEI, I first tried a full wave 20 meter band square loop antenna. On the air comparisons with my low Yagi confirmed instantly that this design was a hands-down winner for working both local and distant stations. I replaced that mono-band loop with a nested loop array for the 20, 17, 15, 12, and 10 meter bands. The antenna blends into the surroundings, so I needed the morning sun shining directly on it to snap the lead photo. This became a nice father-son project with my son Brad, KB3MNE. Here’s how we built the antenna. Construction We constructed the square loops shown in Figure 1 according to the dimensions in Table 1. The loops hang from a tree limb in the vertical plane. Because I feed them This stealthy nested loop is almost invisible among the trees. from the bottom corners, the loops radiate horizontal polarization. Calculate the perimeter size, P, of each holes through the pipe for the loop wire. screws into the PVC to hang the dipole loop by dividing the frequency in MHz After you run the wire through the holes, connectors seen in Figure 2. wrap a bit of electrical tape on each side of into 1005 feet. Table 1 shows the loop Matching and Feeding dimensions. Start with the 20 meter loop, the wire next to the pipe to keep the wire from sliding and to give the pipe additional Each loop antenna feed point impedance is the largest loop. -
Directional Or Omnidirectional Antenna?
TECHNOTE No. 1 Joe Carr's Radio Tech-Notes Directional or Omnidirectional Antenna? Joseph J. Carr Universal Radio Research 6830 Americana Parkway Reynoldsburg, Ohio 43068 1 Directional or Omnidirectional Antenna? Joseph J. Carr Do you need a directional antenna or an omnidirectional antenna? That question is basic for amateur radio operators, shortwave listeners and scanner operators. The answer is simple: It depends. I would like to give you a simple rule for all situations, but that is not possible. With radio antennas, the "global solution" is rarely the correct solution for all users. In this paper you will find a discussion of the issues involved so that you can make an informed decision on the antenna type that meets most of your needs. But first, let's take a look at what we mean by "directional" and "omnidirectional." Antenna Patterns Radio antennas produce a three dimensional radiation pattern, but for purposes of this discussion we will consider only the azimuthal pattern. This pattern is as seen from a "bird's eye" view above the antenna. In the discussions below we will assume four different signals (A, B, C, D) arriving from different directions. In actual situations, of course, the signals will arrive from any direction, but we need to keep our discussion simplified. Omnidirectional Antennas. The omnidirectional antenna radiates or receives equally well in all directions. It is also called the "non-directional" antenna because it does not favor any particular direction. Figure 1 shows the pattern for an omnidirectional antenna, with the four cardinal signals. This type of pattern is commonly associated with verticals, ground planes and other antenna types in which the radiator element is vertical with respect to the Earth's surface. -
Class C Pool of Questions
Class C Pool of Questions T2 1. What is the most common repeater frequency offset in the 2 meter band? T2 2. What is the national calling frequency for FM simplex operations in the 70 cm band? T2 3. What is a common repeater frequency offset in the 70 cm band? T2 4. What is an appropriate way to call another station on a repeater if you know the other station's call sign? T2 5. How should you respond to a station calling CQ? T2 6. What must an amateur operator do when making on-air transmissions to test equipment or antennas? T2 7. Which of the following is true when making a test transmission? T2 8. What is the meaning of the procedural signal “CQ”? T2 9. What brief statement is often transmitted in place of “CQ” to indicate that you are listening on a repeater? T2 10. What is a band plan, beyond the privileges established by the SMA? T2 11. Which of the following is an SMA rule regarding power levels used in the amateur bands, under normal, non-distress circumstances? T2 12. Which of the following is a guideline to use when choosing an operating frequency for calling CQ? T2B – VHF/UHF operating practices: SSB phone; FM repeater; simplex; splits and shifts; CTCSS; DTMF; tone squelch; carrier squelch; phonetics; operational problem resolution; Q signals T2 1. What is the term used to describe an amateur station that is transmitting and receiving on the same frequency? T2 2. What is the term used to describe the use of a sub-audible tone transmitted with normal voice audio to open the squelch of a receiver? T2 3. -
Broadband Antenna 1
Broadband Antenna Broadband Antenna Chapter 4 1 Broadband Antenna Learning Outcome • At the end of this chapter student should able to: – To design and evaluate various antenna to meet application requirements for • Loops antenna • Helix antenna • Yagi Uda antenna 2 Broadband Antenna What is broadband antenna? • The advent of broadband system in wireless communication area has demanded the design of antennas that must operate effectively over a wide range of frequencies. • An antenna with wide bandwidth is referred to as a broadband antenna. • But the question is, wide bandwidth mean how much bandwidth? The term "broadband" is a relative measure of bandwidth and varies with the circumstances. 3 Broadband Antenna Bandwidth Bandwidth is computed in two ways: • (1) (4.1) where fu and fl are the upper and lower frequencies of operation for which satisfactory performance is obtained. fc is the center frequency. • (2) (4.2) Note: The bandwidth of narrow band antenna is usually expressed as a percentage using equation (4.1), whereas wideband antenna are quoted as a ratio using equation (4.2). 4 Broadband Antenna Broadband Antenna • The definition of a broadband antenna is somewhat arbitrary and depends on the particular antenna. • If the impendence and pattern of an antenna do not change significantly over about an octave ( fu / fl =2) or more, it will classified as a broadband antenna". • In this chapter we will focus on – Loops antenna – Helix antenna – Yagi uda antenna – Log periodic antenna* 5 Broadband Antenna LOOP ANTENNA 6 Broadband Antenna Loops Antenna • Another simple, inexpensive, and very versatile antenna type is the loop antenna. -
An Easy Dual-Band VHF/UHF Antenna
An Easv Dual-Band VHFIUHF Antenna Why settle for the performance your rubber duck offers? Build this portable J-pole and boost your signal for next to nothing! You've just opened the box that contains Don't let the veloci9 facfor throw you. 2952 V your new H-T and you're eager to get on L~t4 f The concept is easy to understand. Put the air. But the rubber duck antenna simply, the time required for a signal to that came with your radio is not working where: traveI down a length of wire is longer than well. Sometimes you can't reach the local b4= the length of the 3/4-wavelength the time required for the same signal to repeater. And even when you can, your radiator in inches travel the same distance in free space. This buddies tell you that your signal is noisy. L,, = the length of the l/d-waveleng& delay-the velocity factor-is expressed If you have 20 mhutes to spare, why not stub in inches in terms of the speed of light, either as a buiId a Iow-cost J-pok antemathat's guar- V = the velocity factor of the TV percentage or a decimal fraction. Knowing anteed to oGtperform yourrubber duck?My twin lead the velocity factor is important when design is a dual-band J-pole. If you own a f = the design frequency in MHz you're building antennas and working with 2-meterno-cm B-Ti this antenna will im- Tbese equations are more straight- prove your signal on both bands. -
Wideband Rectenna System for Microwave Power Transfer
Wideband Rectenna System for Microwave Power Transfer by Mohammed Aldosari A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Master of Applied Science in Electrical and Computer Engineering Waterloo, Ontario, Canada, 2018 ©Mohammed Aldosari 2018 AUTHOR'S DECLARATION I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii Abstract One of the fundamental devices in Microwave Power Transfer (MPT) is the rectenna or rectifying antenna, which collects the electromagnetic energy from the free space and convert it directly to a useful DC power. Although many designs of rectenna systems have been proposed, most of them operate in a narrowband frequency and/or a certain level of incident power, which limits the output DC power and the uses of the rectenna. In this work, three novel designs of the rectenna that operate in broadband frequency and wide range of received power are developed. The design methodology for such critical characteristics for the rectenna has been discussed in details. Furthermore, the presented wideband rectennas have the best results comparing to the literature in terms of frequency bandwidth and power range, which indicates great achievement in terms of increasing the output DC power significantly as a result of decreasing the effect of the variation of the frequency and incident power and the ability of harvesting multiple frequencies simultaneously. Furthermore, the wideband rectenna can be considered as an approach to minimize the number of the used rectennas by having a single rectenna that operates in a wide frequency bandwidth and wide range of incident power. -
Transmission Lines, the Most Fundamental Passive Component, Exhibit High Losses in the Millimetre and Sub- Millimetre Wave Regime
Aghamoradi, Fatemeh (2012) The development of high quality passive components for sub-millimetre wave applications. PhD thesis. http://theses.gla.ac.uk/3214/ Copyright and moral rights for this thesis are retained by the Author A copy can be downloaded for personal non-commercial research or study, without prior permission or charge This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the Author The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the Author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given Glasgow Theses Service http://theses.gla.ac.uk/ [email protected] THE DEVELOPMENT OF HIGH QUALITY PASSIVE COMPONENTS FOR SUB-MILLIMETRE WAVE APPLICATIONS A THESIS SUBMITTED TO THE DEPARTMENT OF ELECTRONICS AND ELECTRICAL ENGINEERING SCHOOL OF ENGINEERING UNIVERSITY OF GLASGOW IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY By Fatemeh Aghamoradi November 2011 © Fatemeh Aghamoradi 2011 All Rights Reserved Abstract Advances in transistors with cut-off frequencies >400GHz have fuelled interest in security, imaging and telecommunications applications operating well above 100GHz. However, further development of passive networks has become vital in developing such systems, as traditional coplanar waveguide (CPW) transmission lines, the most fundamental passive component, exhibit high losses in the millimetre and sub- millimetre wave regime. This work investigates novel, practical, low loss, transmission lines for frequencies above 100GHz and high-Q passive components composed of these lines. -
Open-Wire Line – a Novel Approach
Open-Wire Line – A Novel Approach Quantitative tests reveal an easy home-brew method to gain the advantage of low-loss 450 Ohm window line, in places you may have never considered by John Portune W6NBC Coax became popular with the growth of radio in WWII. Hams quickly forgot open-wire line. Yet ladder-type open line has a big advantage over coax – low loss. It is several times better. Why then do so many hams overlook this benefit today? Mostly, I suspect it’s because of ham chit-chat. “Open line” we’ve all been cautioned, “can’t be used near solid objects, especially metal.” Or you shouldn’t run it through a stucco wall, or over a metal window frame. And don’t even dream of laying it right on the ground, in a flower bed or on a metal roof. It may come as a big surprise, but the tests I present in this article strongly suggest that these “no-nos” are largely untrue. You‘ll also see an easy home-brew method for using open line in adverse situations you may have never even considered. I began investigating this topic while prototyping an all-band HF flagpole vertical. (See end of article.) It wasn’t even close to 50 Ohms. Had I fed it with coax, I would have incurred serious line losses. Could I instead feed it with open-wire line? Was it sheer foolishness to even consider laying open- wire line right on the ground or in a flower bed? But that’s where my flagpole’s feed line has to run to get to the feed point. -
A Portable Twin-Lead 20-Meter Dipole
By Rich Wadsworth, KF6QKI A Portable Twin-Lead 20-Meter Dipole With its relatively low loss and no need for a tuner, this resonant portable dipole for 14.060 MHz is perfect for portable QRP. first attempt at a portable problem is that its 300 ohm impedance to 70 ohms, a feed line that is an electri- dipole was using 20 AWG normally requires a tuner or 4:1 balun at cal half wave long will also measure 50 My speaker wire, with the leads the rig end. to 70 ohms at the transceiver end, elimi- simply pulled apart for the length re- But, since I want approximately a half nating the need for a tuner or 4:1 balun. 1 quired for a /2 wavelength top and the wavelength of feed line anyway, I decided To determine the electrical length of rest used for the feed line. The simplic- to experiment with the concept of mak- a wire, you must adjust for the velocity ity of no connections, no tuner and mini- ing it an exact electrical half wavelength factor (VF), the ratio of the speed of the mal bulk was compelling. And it worked long. Any feed line will reflect the im- signal in the wire compared to the speed (I made contacts)! pedance of its load at points along the of light in free space. For twin lead, it is Jim Duffey’s antenna presentation at the feed line that are multiples of a half wave- 0.82. This means the signal will travel at 1999 PacifiCon QRP Symposium made me length. -
Realization of a Planar Low-Profile Broadband Phased Array Antenna
REALIZATION OF A PLANAR LOW-PROFILE BROADBAND PHASED ARRAY ANTENNA DISSERTATION Presented in Partial Ful¯llment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Justin A. Kasemodel, M.S., B.S. Graduate Program in Electrical and Computer Engineering The Ohio State University 2010 Dissertation Committee: John L.Volakis, Co-Adviser Chi-Chih Chen, Co-Adviser Joel T. Johnson ABSTRACT With space at a premium, there is strong interest to develop a single ultra wide- band (UWB) conformal phased array aperture capable of supporting communications, electronic warfare and radar functions. However, typical wideband designs transform into narrowband or multiband apertures when placed over a ground plane. There- fore, it is not surprising that considerable attention has been devoted to electromag- netic bandgap (EBG) surfaces to mitigate the ground plane's destructive interference. However, EBGs and other periodic ground planes are narrowband and not suited for wideband applications. As a result, developing low-cost planar phased array aper- tures, which are concurrently broadband and low-pro¯le over a ground plane, remains a challenge. The array design presented herein is based on the in¯nite current sheet array (CSA) concept and uses tightly coupled dipole elements for wideband conformal op- eration. An important aspect of tightly coupled dipole arrays (TCDAs) is the capac- itive coupling that enables the following: (1) allows ¯eld propagation to neighboring elements, (2) reduces dipole resonant frequency, (3) cancels ground plane inductance, yielding a low-pro¯le, ultra wideband phased array aperture without using lossy ma- terials or EBGs on the ground plane. -
Amplifiers, Sequencing, Phasing Lines, Noise Problems Tom Haddon, K5VH and New Modes of Operation
PROCEEDINGS of the 48th Conference of the July 24-27 Austin, Texas 2014 Published by: ® i Copyright © 2014 by The American Radio Relay League Copyright secured under the Pan-American Convention. International Copyright secured. All rights reserved. No part of this work may be reproduced in any form except by written permission of the publisher. All rights of translation reserved. Printed in USA. Quedan reservados todos los derechos. First Edition ii CENTRAL STATES VHF SOCIETY 48th Annual Conference, July 24 - 27, 2014 Austin, Texas http://www.csvhfs.org President: Steve Hicks, N5AC Fellow members and guests of the Central States VHF Society, Vice President: Dick Hanson, K5AND In 2004, a friend invited me to attend an amateur radio conference Website: much like this one, and that conference forever changed the way I Bob Hillard, WA6UFQ looked at amateur radio. I was really amazed at the number of people and the amount of technology that had come together in Antenna Range: Kent Britain, WA5VJB one place! Before the end of the conference, I had approached Marc Thorson, WB0TEM one of the vendors and boldly said that I wanted to get on 222- Rover/Dish Displays: 2304. Jim Froemke, K0MHC Facilities: As others have pointed out in the past, one of the real values of Lori Hicks attendance is getting to know other died-in-the-wool VHF’ers. Yes, Family Program: the Proceedings is a great resource tool, but it is hard to overstate Lori Hicks the value of the one on one time with the real pros at one of these Technical Program: conferences. -
A Multi-Tone Rectenna System for Wireless Power Transfer
energies Article A Multi-Tone Rectenna System for Wireless Power Transfer Simone Ciccia 1,* , Alberto Scionti 1, Giuseppe Franco 1, Giorgio Giordanengo 1 , Olivier Terzo 1 and Giuseppe Vecchi 2 1 Advanced Computing and Application, LINKS Foundation, 10138 Torino, Italy; [email protected] (A.S.); [email protected] (G.F.); [email protected] (G.G.); [email protected] (O.T.) 2 Department of Electronics and Telecommunications, Politecnico di Torino, 10129 Torino, Italy; [email protected] * Correspondence: [email protected] Received: 3 April 2020; Accepted: 4 May 2020; Published: 9 May 2020 Abstract: Battery-less sensors need a fast and stable wireless charging mechanism to ensure that they are being correctly activated and properly working. The major drawback of state-of-the-art wireless power transfer solutions stands in the maximum Equivalent Isotropic Radiated Power (EIRP) established from local regulations, even using directional antennas. Indeed, the maximum transferred power to the load is limited, making the charging process slow. To overcome such limitation, a novel method for implementing an effective wireless charging system is described. The proposed solution is designed to guarantee many independent charging contributions, i.e., multiple tones are used to distribute power along transmitted carriers. The proposed rectenna system is composed by a set of narrow-band rectifiers resonating at specific target frequencies, while combining at DC. Such orthogonal frequency schema, providing independent charging contributions, is not affected by the phase shift of incident signals (i.e., each carrier is independently rectified). The design of the proposed wireless-powered system is presented.