ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

The Pros and Cons of Slot Antennas

Updated on November 19, 2017
tamarawilhite profile image

Tamara Wilhite is a technical writer, industrial engineer, mother of 2, and a published sci-fi and horror author.

What Is a Slot Antenna?

Slot antennas typically consist of a metal surface like a flat plate with one or more “slots” cut out. This makes slot antennas a type of aperture antenna. These slots may be holes instead of rectangular slots.

The size and shape of the slot and the driving frequency determine the radiation pattern of the slot antenna. Slot antennas are roughly half of a wavelength long, while the width should be a small fraction of the wavelength.

The slot antenna behaves in accordance with Babinet’s principle as a resonant radiator. Babinet’s principle relates the slot antenna to a dipole, though the polarization of the slot antenna is rotated compared to that of a dipole antenna. (A vertical dipole has a vertical field, whereas it is horizontal for a vertical slot antenna.) You can approximate the performance of the slot antenna to a dipole antenna with the dimensions of the slot. That theoretical dipole antenna is called a “complimentary dipole”.

Closeup of slot antenna.
Closeup of slot antenna. | Source

The Advantages of Slot Antennas

One benefit of the slot antenna is its sheer simplicity. Widen the slot, and it is equivalent to a thicker dipole. This is equivalent to increasing the bandwidth.

Slotted antennas can transmit high power levels. This is why they are popular in applications like navigation systems and weather radar.

When you’re selecting an outdoor antenna, the low wind load of the slot antenna is a point in its favor.

You can hid a slot antenna within a metallic object like a fake air vent, making them ideal for covert communications. They can also be manufactured to conform to the surface on which they are mounted like an aircraft’s skin.

Slot antennas are easy to mass produce with any technology. The slot antenna can be cut out of whatever surface the antenna is mounted on. You tune the antenna performance by altering the slot size, shape and the design of the cavity behind it.

Slot antenna radiation patterns are roughly omni-directional.

More current is required to produce a given power output with a dipole antenna than is achieved with a slot antenna.

Slot antennas are more efficient than a comparably sized dish antenna. This makes slot antennas an ideal choice for radar dishes in the nose cone of an aircraft, since you can make the slot antenna smaller where a few more inches dramatically improves the aerodynamics.

The Disadvantages of Slot Antennas

Slot antennas have low radiation efficiency.

Slot antennas have high cross-polarization levels.

Waveguide slot antennas are heavy compared to their dipole equivalents.

Observations about Slot Antennas

Slot antennas are sometimes called slot radiators. A slot antenna is not the same thing as a slot periodic antenna.

A single narrow slot antenna can work on frequencies plus or minus ten percent of their resonant frequency. This is difficult to achieve with array antennas.

The longer the slotted antenna, the narrower the beam. However, this is often resolved by arranging slotted waveguides in parallel.

A vertical slot antenna has a horizontal electric field. A horizontal slot antenna has a vertical electric field. In contrast, a vertical dipole antenna has a vertical electrical field.

Slot antenna from an aircraft nose cone.
Slot antenna from an aircraft nose cone. | Source

Common Applications of Slot Antennas

Slot antennas are regularly used for microwave and UHF frequencies, though they were originally invented for VHF television broadcasting. Most slot antennas are used for frequencies between 300 MHz and 25 GHz.

Slotted pole antennas or pylon antennas are narrowband antennas used for broadband applications. Radial line slot antennas are periodically used for DBS reception. One of the most common uses for slot antennas is as radar antennas, especially navigation radar. They are sometimes used as sector antennas for cell phone base stations. They can be used as an array when fed by a waveguide.

Slotted antennas can be made using the same technology as printed circuit board antennas like these UWB and Vivaldis.
Slotted antennas can be made using the same technology as printed circuit board antennas like these UWB and Vivaldis. | Source

© 2017 Tamara Wilhite

Comments

Submit a Comment

  • someonewhoknows profile image

    someonewhoknows 

    10 months ago from south and west of canada,north of ohio

    That's a SLOT of Antennas lol!

  • profile image

    Haider Jahan 

    10 months ago

    Awesome information.

working

This website uses cookies

As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

Show Details
Necessary
HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
LoginThis is necessary to sign in to the HubPages Service.
Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
AkismetThis is used to detect comment spam. (Privacy Policy)
HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
Features
Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
MavenThis supports the Maven widget and search functionality. (Privacy Policy)
Marketing
Google AdSenseThis is an ad network. (Privacy Policy)
Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
Index ExchangeThis is an ad network. (Privacy Policy)
SovrnThis is an ad network. (Privacy Policy)
Facebook AdsThis is an ad network. (Privacy Policy)
Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
AppNexusThis is an ad network. (Privacy Policy)
OpenxThis is an ad network. (Privacy Policy)
Rubicon ProjectThis is an ad network. (Privacy Policy)
TripleLiftThis is an ad network. (Privacy Policy)
Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
Statistics
Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)