Antenna trap design. Thus, it is of paramount importance that the trap design be such as to assure stability of resonance in wide extremes of temperature and Sep 2, 2020 · Review of the Packtenna Antenna systems in the November 2016 QST magazine. 100 Antenna Trap Design Using a Home Computer Larry V. Jan 11, 2021 · Designing Self Resonant Coils for Antenna Traps and Chokes. • NO-TRAP DESIGN. Because of resonance, the trap presents a high impedance to antenna system. Just think–you could be operating 80 meters on a relatively small lot. Suppose one day you're walking down the street and a kind but impatient person runs up and asks you to design an antenna for them. Handles power up to 100W of RF. It requires some sort of ground connection to work. Antenna trap kit building instructions; Construction manual antenna trap V2; Manual 1:49 UnUn for End Fed antenna’s 100 Watt; Manual 1:49 UnUn for End Fed antenna’s 250 Watt; Manual 1:49 UnUn for Mini End Fed antenna; Manual ZS6BKW, G5RV (junior/mini) Technique. • HARDWARE. A trap is a parallel circuit of L and C on the frequency you want to close an antenna segment. 07 dB less than the trapless dipole. Description. As far as traps go, you can buy them Build a Space Efficient Dipole Antenna for 40, 80 and 160 Meters. To construct a square loop antenna you can either bend the tube at 90 ̊, or use 90 ̊ solder fittings. Verticals are commonly installed at ground level, although you can also place a vertical on the . A new perspective on the analysis and design of this popular antenna element. A trap can properly be considered the "weak link" in the chain of components that comprise a multi-band antenna. • FULLY ASSEMBLED. Not having to be concerned about loss due to SWR is a good thing! There is a problem, however: Modern transceivers are designed for unbalanced coaxial cables, not balanced feed lines. The trap blocks the RF at F1 from continuing out the wire, making the center portion of the antenna operate as a half wavelength on F1. You need this - traps with lower loss, higher Q, increased power Let's get right down to the study of antennas and Antenna Basics. When the frequency of the electric wave The trap is situated 1/4 wave length from the boom of a yagi and is similar to that of an open switch. Additionally, RF matching circuits must be configured to allow the antenna to operate its radio system at the highest efficiency and performance levels. The upper right plot shows the 80-meter SWR has a much narrower bandwidth than the other three bands. Steven Petten, CEO & Founder of AEM Antennas. Total coaxial trap loss at resonance on 40m= 1. A simplified electrical model of the trap shows the physical inductor and capacitor and a small parasitic resistance (R P ) (Figure 4). The antenna, a 15' vertical design, facilitated contacts with over 200 countries worldwide. W8JI is an authority on all aspects of antenna design - including traps. U (antenna tuning unit). 6 dB. I’ve built one for 40M and it worked well on 40M and higher. For light antennas and field work, solder directly to the trap pcb. The article by K7ZB introduces a simple 10-20m DX antenna suitable for deed-restricted lots. This tends to be a reasonable compromise between trap loss and ease of antenna adjustment. Installing traps on an antenna allows you to turn your EFHW into a multiband antenna. East, W1HUE You can make traps for multiband antennas from nothing but lengths of coaxial cable. The list of major tuning / design parameters include the following: An antenna is an array of conductors ( elements ), electrically connected to the receiver or transmitter. It is approximately 110 feet in length and provides a relatively low SWR on these bands. No need to pull the antenna or change elements. 8:1, followed by the 40 m wires then the 80 m wires. Photo 2: The damaged antenna trap showing the outermost metal tube (which pulled completely Oct 16, 2021 · Antenna Design Tools. We can use the gain figure, as a standard against which to measure trap antennas for two bands. It is used to make up a dual-band 80m/40m dipole where previously only a 40m dipole THE N4UJW ANTENNA PROJECTS DESIGN LAB. Jul 11, 2021 · Adding a trap to an End Fed Half-Wave Antenna can bring you a few surprises. 5 m between balun and 20m trap, 5. SOTABEAM HF Antenna Trap Kits are a clever design with flexible mounting arrangements to make them easy to build and use. T he vertical is a popular antenna among hams who lack the space for a beam or long wire antennas. Our traps are quick and easy to make – and have a unique design making them perfect for use in the field or at home. This page describes the design and construction materials W8WWV used to build a coaxial cable trap. A trap design guide is provided below to aid multiband dipole construction. 100 MHz trap would be needed. Note the axial crack in the blue housing. For n working frequencies of an antenna, you need n-1 traps in each part of the antenna. DX-A - 160-80-40 Meter 1/4-wave Twin Sloper - A top low frequency DX antenna. 8-MHz trap is shown without its protective electrical-tape wrap to show the After attempting many antenna designs to overcome the physical constraints of my back garden, it was time to try a trapped dipole. Thanks to Peter of UK's Waters & Stanton Ham Radio Store for this useful antenna accessory. In this simple case, the trap is resonant at frequency F1, and the distance from the feedpoint to the trap is set for that frequency. In the low frequency limit, the traditional inductance calculations work okay and can give A new trap design, using only RG-58 and PVC pipe, yields better space efficiency than conventional coaxial traps. Conversely, the 14 MHZ signal perceives the 21 and 28 MHZ traps as a closed switches at 14 MHZ. W2VS traps are available for 80 meters and up in two versions. 95 plus $5 shipping and handling. e. 15 MHz)= 1. Cebik W4RNL (SK) popularized the 44-foot doublet for 40M-10M. With information from ham radio sites and from (google cheap and easy tv antenna because I am not allowed to post url's), I decided on the following design based on a simple folded dipole. Simple and practical three-band TRAP DIPOLE. Posted on November 4, 2014. For hobbyists and small companies just starting out in the field, it can get very costly if you only need to design simple antennas. 161. the coax trap program computes design parameters for the construction of coaxial traps for hf usage typically these are constructed from pvc tube and rg58 59 coax. The smallest antennas can be made with copper shielded coax cable e. 06 dBi, a mere 0. The 6-BTV is designed to provide excellent performance on the 10, 15, 20, 30, 40 and 75/80 meter bands, using four traps and the RM-80S resonator. The trap can consist of a coil and a separate HV-capacitor. The benefits of this helix antenna is it has a wide bandwidth, is easily constructed, has a real input impedance, and Jun 9, 2021 · Calculate trap capacitance. The 20 meter signal and uses the whole length of the element. You need this—traps with lower loss, higher Q, increased power-handling capability and four-band coverage! This improved multiband trap dipole introduces a new trap design and a change in trap location. In principal, trap antennas are still a very good compromise antenna for a compact multi-band design. Being an amateur radio operator and an HF shortwave crystal set enthusiast, it accrued to me that it would be fun and doable to design a 20 & 30 or 20 & 39 meter vertical antenna, featuring a coaxial trap to isolate the 20-meter portion. Jun 23, 2020 · This electrically shortens the antenna and may provide sufficient effective shortening to provide a low SWR without any trimming. This is expected due to the shortened antenna design with a loading coil. The Pacific Antenna Dual Band Trap Dipole kit provides a lightweight, portable trap dipole. Enter desired frequency MHz, Results inductance L (uH) Capacitance C (pF) post 17 May 2023. They feature special traps made with of PTFE (Teflon®) insulated coax for high Q and low losses, offer high performance multi-band operations—and are excellent shortened Antenna Trap Calculator. Over the years a number of multiband trap dipoles, Yagis, and verticals have been available for ham radio communication. Fig 2—The improved coaxial-cable traps use two layered windings to provide an unusually high inductance-to-capacitance ratio, higher Q, and twice the breakdown voltage of single- layer traps. Oct 31, 2016 · The total length of this dipole antenna, including the two traps, is only 43. An Improved Multiband Trap Dipole Antenna This improved multiband trap dipole introduces a new trap design and a change in trap location. Note that loss is maximum at trap resonance!!! Never make a trap resonant on the desired operating frequency!! W2LH ARRL Handbook Trap Design 100pF #12awg Miniductor trap 40m 2:1 VSWR Antenna design calculators category is a curation of 105 web resources on , Parallel Square Conductor Transmission Line Calculator, HB9CV Online Antenna Calculator, RF Toroid Calculator. The Hustler® BTV antennas provide automatic This antenna is based on the 80/40M trap dipole design found in the ARRL Handbook. It requires only one very tall center support, with lower supports for the wire ends. May 24, 2024 · 17/30 Meter Dipole. The authors demonstrate in calculation, simulation, and measurement that trap dipoles antennas are not matched or resonant at the same frequency as the trap load resonance. Oct 5, 2023 · The work presents a significantly revised analysis of a classic resonator loaded antenna– the trap dipole. Lofgren, W6JJZ To address questions about availability of our REYCO Antenna Trap line. The most popular helical antenna (helix) is a travelling wave antenna in the shape of a corkscrew that produces radiation along the axis of the helix antenna. Any failure or malfunction of one of the traps will put the antenna out of operation or, at least seriously effect its performance capability. 7 Mhz traps for W3DZZ. An antenna analyzer makes tuning the antenna easier but it can also be adjusted by checking the SWR at the lower and 1”Trap and Stub Dipole Antennas for Radio Amateurs” is available from Al Buxton, W8NX, PO Box 174, Columbus, Ohio 43216-0174. " Although more expensive than Unadilla traps ($76/pair versus $52/pair), the mechanical design seemed more robust so a pair was ordered. Find Kelemen Trap Dipole Antennas and get Free Shipping on Most Orders Over $99 at DX Engineering! Kelemen Trap Dipole Antennas are high-quality, heavy-duty pre-assembled wire antennas intended for permanent installations. 5 feet/13. I specifically wanted to work 20 and 40 meters, so a dipole with a 14. Inductance L (µH) Capacitance C (pF) Capacitance C (pF) Jan 24, 2023 · Antenna design is a complex process involving the careful consideration of various factors to ensure the design aligns with the intended application. Article in Dutch with some interesting pictures. Antennas can be designed to transmit and receive radio waves in all horizontal directions equally ( omnidirectional antennas ), or preferentially in a particular direction ( directional, or high-gain, or "beam" antennas). They are essentially resonant circuits used to isolate parts of an antenna at certain frequencies, enabling multi-band functionality. • SEVERE WEATHER RATED. The easiest way to determine the values of this circuit is to measure C, L and Rs. 2 MHz trap-loaded dipole showed a free space gain of 2. -----Thanks for joining us This video is about how to use the ***FREE*** 4NEC2 Antenna Modeling application to model and design a trapped dipole antenna. The Trap in the figure is a 1/4 λ transmission line short-circuited at one end. Hygain, Mosley, Cushcraft and others use traps to get the antenna to perform on several bands. Here's how to make them. 1) Re-epoxy the outer metal tube back into the housing. The tuning process is the same as for the 40/80 dipole, excpet the 20 m wires are trimmed first to an SWR of 1. (50Ω Coaxial cable ,For example RG- 58/U),The resonant frequency is 14MHz. • ALPHA DELTA MANUFACTURED ANTENNAS NOW MADE IN OUR IS0-9001 CERTIFIED PRODUCTION FACILITY. Nov 30, 2022 · Here are antenna analyzer screen shots of the impedance data and SWR plots. Q3 A new trap design, using only RG-58 and PVC pipe, yields better space efficiency than conventional coaxial traps. This type of antenna is designed for one principal amateur HF band, usually 80 meters or 40 meters, but typically displays VSWR minima on several higher bands, and can therefore be a good multi-band Jul 7, 2021 · This is post 2676 in a continuing series of simple ham radio antennas. 5 m between 20 m trap and 40 m trap and 11 m between the 40 m trap and the end of the antenna. I have provided all the files Homebew Coax Traps. These traps will wor Building Coaxial Traps. Design an End-Fed Half-Wave (EFHW) antenna, in either an inverted-L or inverted-Vee form, using a single main support. May 31, 2021 · [2][3] This design used double-wound traps made from only the inner conductor of RG-58 coax. J-Poles-- From The ARRL Super J-Pole Antenna (Collinear Design) - By KB0YKI 2M, 220, 440, 6M J-Poles Antennas -- Dimensions, matching, everything -- from Bux CommCo -- Be sure to read importance of a decoupling loop. Online calculator will produce the text required to be put in your beacon string to display to others your PHGR. When you switch bands on your radio, the antenna is automatically set for the band you have chosen. Mouse-over any image to see it larger! Let’s work through the design of a simple-to-construct low-cost antenna ‘trap’ - like the one pictured above - for the 40 metre band, i. May 17, 2023 · Antenna Trap Design. Design your own antenna trap online. An antenna may include components not connected to the transmitter The smaller the backyard, the less room that we have to construct a full-size 135' level center-fed doublet as an all-band HF antenna. Swaging of element sections creates a more attractive antenna, reduces wind load, eliminating possible vibrations causing metal fatigue. Q2: Can I use this formula for any frequency? Yes, you can use the formula L=31. A trap is used as a blocking component for one specific frequency. Three-band Linear Trap Dipole designed by G3TKN. May 10, 2012 · 1. Resources listed under Antenna Calculators category belongs to Antennas main collection, and get reviewed and rated by amateur radio operators. The trap design was a little more complicated, but would almost fit into my back yard. Jan 3, 2010 · I have searched the web unsuccessfully for a simple antenna design for receiving low vhf HDTV signals (channel 3, 55 miles away). But in time, the traps deteriorate and problems arise. The antenna wire lengths before trimming are 5. TRAP is like an electronic switch. The 3. Trap is a combination of an inductor and a capacitor, usually connected in parallel by an inductor and a capacitor. Traps stay on frequency in steaming jungles and deserts; in polar regions. I decided to pursue construction of this antenna, and bend the 160 meter end wire, if necessary to fit into the yard. These helix antennas are referred to as axial-mode helical antennas. Homebrewing traps for the W3DZZ wire dipole Antennas. 5 MHz reception. According to Cebik’s analysis, this length The Hustler® 6-BTV is a six-band trap vertical antenna. Antenna Trap Design. HF Kits offers you DIY kits and spare parts for ham radio amateurs. These antennas will be shorter than a full-size dipole at Coax trap 40 meter 2:1 VSWR ~ 80 kHz. A. Nov 26, 2019 · Trap resonant in the amateur band: Antenna A=66 feet long; each L/C combination is resonant in 7Mhz band. Antenna impedance – Theory and practice examples; Antenna Wire An antenna trap is used to isolate specific frequency bands in multi-band antennas. PHGR Calculator Power, Height, Gain and Beacon Rate. HF antenna traps offer an easy and efficient way of making a multi band wire antenna. 5 across both bands. Manufacturers extolled their antennas based on “low loss” trap design, implying their antenna would outperform the others. Traps simply act like a switch electrically cutting off the rest of the antenna at its design frequency, and Traps are tuned circuits inserted along the length of the antenna. the antenna or losing power to the effects of SWR. The first thing we see is that performance of a two band trap antenna of conventional design, depends very heavily on the Q of the trap. This electrically shortened dipole is similar in appearance to a trap dipole except the "traps" consist of coils only, causing the antenna to operate not unlike two mobile inductively loaded whips, mounted horizontally base-to-base. It is true that we have momentarily retired the line while we talk with companies and individuals interested in manufacturing and maintaining this product here in the USA. Total coaxial trap loss 100kHz off-resonance (at 7. You will find here antenna, Balun, traps, endfed or transformer DIY kits and parts. Available in 20+40M and 17+30M versions. Handbooks reassure us that the inverted-V will perform quite well, with only a small reduction in gain and a 4 days ago · Antenna traps are critical components in the design and operation of antennas, especially those that need to operate efficiently over multiple frequencies. For example a 2-band-dipole needs one trap in each half of the antenna. 9 ohms. Antenna design tools are very expensive. The REYCO W2VS line of traps provide a highly sought-after solution to a multiband wire antenna. T. In an electrical sense, a vertical is a dipole with half of its length buried in the ground or “mirrored” in its counterpoise system. Note: Configuration and height above ground will affect the match, especially on 40M. HF. So between the two Traps, the Dipole works at 14MHz; but for 7MHz, the Trap is inductive. Use as a dipole, inverted V or upright V antenna configuration. The most common are those with traps, or parallel tuned circuits, that are resonant at or just below the edge of the higher frequency band to be covered, with extensions to make up the length of the lower band. Peter G3OJV, provides a few warnings. Many multiband wire or tubing antennas of your own choosing, employing both trap and/or short stub technology can be designed with this software. The antenna features double-coaxial-cable-wound traps having lower reactance and a higher quality factor (Q) than earlier coax-cable traps. Kevlar. Price: $34. This article is a well-organized tutorial that explains the theory, design, and construction of a 20/40 meter trap dipole antenna, including a list of materials and how to build the traps. TYPICAL TRAP FOR 20–15–10 There are two types of trap antennas, with examples illustrated in Figure 1. +44 (0) 7753225261. Inductance L (µH) Jul 5, 2021 · Here is a simple construction project that you can carry out. Traps are done with coax cable turns, dimensions are in the attached schema. A nano VNA, grid-dipper or spectrum analyzer is needed to tune the stage. A decent antenna for that band needs to be much longer. To operate multiband, traps had to be placed at appropriate points to shorten the antenna to a 1/4 wave on various. There are many trap designs, but here is a table of one pretty good design with coils of various Qs. 8-MHz trap is shown without its protective electrical-tape wrap to show the HF Trap Calculator. That’s why this antenna design has been a favorite for so long. The design process and specs follow. Enter desired frequency MHz. The performance of any antenna depends upon many factors, not the least of which is its design. • STAINLESS STEEL. Depending on your tuner, it may also be usable on the next lower band. Nov 24, 2007 · This Antenna design was one that I used about 4 years ago, it worked exceptionally well on 80m and 40m. Both efforts are vital to creating an Verticals. Mar 10, 2020 · Many folks suggest making the doublet a half-wavelength long at the lowest band you intend to use. The W2AU balun is used with a pair of 40M traps to create a multiband dipole antenna capable of operating on 80, 40, 20, 15 and 10 meters. Traps can be one way round multiband coverage without the need of an atu. 5% of the source current. B. After acquiring a MTR3b for SOTA activations I decided I needed a different antenna than the End Fed Random Among their products are antenna traps intended for multiband dipoles and one of them, the T-40, is for use in an 80/40 meter dipole that can also operate on 20, 15 and 10 meters with "somewhat higher VSWR. The narrow bandwidth means the antenna match network needs to be re-adjusted if I change the Photo 1: A typical Unadilla KW40 antenna trap. Low Cost Antenna Traps. 26 meters--small enough to fit in many urban backyards. Note that loss is maximum at trap resonance!!! Never make a trap resonant on the desired operating frequency!! W2LH ARRL Handbook Trap Design 100pF #12awg Miniductor trap 40m 2:1 VSWR May 5, 2023 · A simple trap dipole for two frequencies. An end-fed wire often seems like the simplest type of antenna, but getting it to work well is actually rather complex. Trap Antenna Design Calculator. 4 In order to design multiband anten-nas with programs such as EZNEC,5 traps must be modeled as “loads,” de-fined by their equivalent circuit as shown in Fig 3. The primary issues are: The impedance varies over a very wide range, depending on the length in wavelengths. The trap showed an impedance of 5175 - j22155 ohms, effectively terminating the antenna. Our traps can be used either way, it's your choice. It also has the added advantage of shortening the overall length of an antenna significantly ,especially if more than one set of traps is used. It worked well also on 20m with the use of an A. W8NX details a new coax trap design used in two multiband antennas; one covering 80, 40, 20, 15, and 10 meters, and the other covering 80, 40, 17, and 12 meters. . As a work-around, many amateurs try the inverted-V configuration. Yet big signals on the band did not come from these verticals. Fortunately, several low cost or open-source solutions exist that can help you on your way. 8/f for any frequency in MHz to calculate the inductance of an antenna trap. A resonant trap is a bit like a frequency-sensitive insulator. A trap was designed using VE6YP's design tool which appears to embody the formulas that are commonly expressed as describing the resonance of the trap. This article gives some useful tips on using antenna traps. The size of the antenna makes a Half wave length on 80 meters, and with the traps a half wave on 40m with a SWR (standing wave ratio) of 1:1-1. Professional help was required for this project, I needed well-made traps for this antenna to perform well. Each kit includes parts to build two (2) traps. The project requires only a few basic tools and readily available materials. By using traps, the antenna works on all three bands with no operator interaction. the 7 MHz or 40 meter (USA) band. Traps for different bands can be combined onto one dipole to create a single antenna tuned for maximum gain on all your favorite bands, from 160 to 10. We will take the inductive loading coils and convert these into a parallel LC circuit, aka dipole traps. It helps prevent interference between different frequency bands and allows for better signal tuning. This can be applied in for example a wire antenna. The 21. Coaxial Traps for multiband antennas. Resonant traps are parallel resonant at some frequency, where the trap’s high impedance effectively isolates or disconnects the remaining wire from the antenna segment between the traps. Approximately 30% shorter than a full size dipole. They are available in two power levels, 100 watt traps are listed here as SBM-HFAT-101 and 20 watt traps are SBM-HFAT-102. The same electric circuit is present on 10 meters. To connect a balanced feed line to our modern Antenna trap kit, this kit contains everything to make your own trap. The feedpoint impedance was 73. Coax trap 40 meter 2:1 VSWR ~ 80 kHz. A lowly coil of wire can be surprisingly difficult to understand and model correctly. So for a 20m-40m dipole, resonant your trap at 14. But how much coax, and wound in what coil dimensions? Avoid the tedium of cut-and-try designs with this simple computer program. net Abstract A coaxial-cable trap dipole antenna installed in the attic provides a surprisingly effective solution to HF operation on the 10, 15, 20, 30, 40, and 80 meter amateur bands at a QTH with restrictive covenants that prohibit outside antennas. The formula for capacitive reactance is: π X C = 1 2 π f C. Oct 4, 2020 · An End Fed Half Wave (EFHW) antenna for operation on 20, 30 and 40 meters was built for SOTA operation. Build a Space Efficient Dipole Antenna for 40, 80 and 160 Meters. For an easy design of coaxial traps, VE6YP offers a program in the internet. Its design employs a telescopic aluminum tube and radial wires for multi-band operation, requiring an external antenna tuner for optimal performance. The report SOTAbeams HF Antenna Trap Kits. g. The new analysis unites traditional high impedance trap loads with a wide variety of resonant and reactive loads Inverted Vee Antenna-- From The N4UJW Antenna Design Lab Inverted Vee Antenna Design-- Nice Illustrations - From K7MEM. 0 MHz. The coax trap will also shorten the length of the wire antenna, making it perfect for the EFHW antenna designer. Toggle navigation. Since traps are parallel circuits, first set X C equal to X L: X L = X C π π 2 π f L = 1 2 π f C π L C = 1 ( 2 π f) 2 π C = 1 ( 2 π f) 2 L π This multiband antenna 10-80 meters is a home made project by I1BAY. Listed under the Antennas/Traps category that is about About antenna traps. May 26, 2022 · Traps act like a switch, electrically cutting off the rest of the antenna at the trap’s design frequency and functioning as a loading coil below the antenna’s resonant frequency. Feb 16, 2021 · Least served by my other antennas are the 40m and 80m bands, so I included a coil “trap” for 40m in the design options options for this big inverted L. Traps are modelled in antenna software with a model that assumes a perfect capacitor and an inductor with a small series resistance which takes into account the resistance of the conductor and core losses. We know that many antennas can effectively resonate and work in more than one band, one of which is called a Trap antenna. Rated for 2KW PEP. Refurbishing Old Trap Antennas. 06 dB. 103 The Suburban Multibander Charles A. THE BEST HAM RADIO OPERATORS HAVE GOOD ANTENNAS! You can't work them if you can't hear them! Design or build your antenna here! Antenna project contributions are from all over the world! HF, Vhf, Uhf antenna projects and lots more! Most are designed for ease of construction and expense! Antenna Trap Design Enter desired frequency MHz. Delta Loop Antennas (11) Double Bazooka (10) Half Wave End Fed Antenna (27) HF G5RV Antenna (2) May 21, 2021 · The Coaxial Trap, great for more than one band on a single antenna. Has been used for SOTA activations with great results. RG 405, whereas a 500mm x 500mm (20" x 20") loop requires 15mm (1⁄2”) Ø copper tube, whilst larger loops should use 22mm (3⁄4") Ø tube. Model DX-CC multi-band 80, 40, 20, 15 and 10 meter dipole. Long / Random / End-fed Antennas. Category : Antennas/Traps. The design of the 6-BTV is sleek, with no capacity spiders and is approximately 25 feet tall. The design tool give construction details and calculates the inductance and capacitance of the elements and their reactance at resonance, but does not estimate resistance, or impedance at any This is the one you've been waiting for - the traps to go with the micro End Fed Halfwave (EFHW) antenna build. Antenna Calculator Links →. Trapped EFHW in operation on Granite Chief W6/NS-115, the feed point is supported by a line to a tree. I use coils of wire or coils of coax cable as trap inductors for various antenna designs that I have built. September 2014. "Sure", you quickly reply, adding "what is the desired frequency, gain, bandwidth, impedance, and polarization?" May 25, 2021 · So how can you squeeze multiband HF antennas into a limited space? Choose antennas with parallel tuned circuits, known as traps. Peter shows us how to design, build, and test a simple trap for an HF antenna. Weighs approximately 4 ounces. Current levels beyond the traps were not significant, never rising above 2. An Attic Coaxial-Cable Trap Dipole for 10, 15, 20, 30, 40, and 80 Meters John DeGood, NU3E nu3e@arrl. L. 2) Fill the axial cracks in both traps with some type of weatherproofing sealer to prevent moisture ingress. A coaxial cable trap is a parallel resonant circuit that is usually inserted in an antenna element to enable multiband operation. ua lj ov fc ii no eo sz sl qo